// CodeMirror, copyright © by Marijn Haverbeke and others // Distributed under an MIT license: codemirror.net/LICENSE

// This is CodeMirror (codemirror.net), a code editor // implemented in JavaScript on top of the browser's DOM. // // You can find some technical background for some of the code below // at marijnhaverbeke.nl/blog/#cm-internals .

(function(mod) {

if (typeof exports == "object" && typeof module == "object") // CommonJS
  module.exports = mod();
else if (typeof define == "function" && define.amd) // AMD
  return define([], mod);
else // Plain browser env
  this.CodeMirror = mod();

})(function() {

"use strict";

// BROWSER SNIFFING

// Kludges for bugs and behavior differences that can't be feature
// detected are enabled based on userAgent etc sniffing.

var gecko = /gecko\/\d/i.test(navigator.userAgent);
// ie_uptoN means Internet Explorer version N or lower
var ie_upto10 = /MSIE \d/.test(navigator.userAgent);
var ie_11up = /Trident\/(?:[7-9]|\d{2,})\..*rv:(\d+)/.exec(navigator.userAgent);
var ie = ie_upto10 || ie_11up;
var ie_version = ie && (ie_upto10 ? document.documentMode || 6 : ie_11up[1]);
var webkit = /WebKit\//.test(navigator.userAgent);
var qtwebkit = webkit && /Qt\/\d+\.\d+/.test(navigator.userAgent);
var chrome = /Chrome\//.test(navigator.userAgent);
var presto = /Opera\//.test(navigator.userAgent);
var safari = /Apple Computer/.test(navigator.vendor);
var khtml = /KHTML\//.test(navigator.userAgent);
var mac_geMountainLion = /Mac OS X 1\d\D([8-9]|\d\d)\D/.test(navigator.userAgent);
var phantom = /PhantomJS/.test(navigator.userAgent);

var ios = /AppleWebKit/.test(navigator.userAgent) && /Mobile\/\w+/.test(navigator.userAgent);
// This is woefully incomplete. Suggestions for alternative methods welcome.
var mobile = ios || /Android|webOS|BlackBerry|Opera Mini|Opera Mobi|IEMobile/i.test(navigator.userAgent);
var mac = ios || /Mac/.test(navigator.platform);
var windows = /win/i.test(navigator.platform);

var presto_version = presto && navigator.userAgent.match(/Version\/(\d*\.\d*)/);
if (presto_version) presto_version = Number(presto_version[1]);
if (presto_version && presto_version >= 15) { presto = false; webkit = true; }
// Some browsers use the wrong event properties to signal cmd/ctrl on OS X
var flipCtrlCmd = mac && (qtwebkit || presto && (presto_version == null || presto_version < 12.11));
var captureRightClick = gecko || (ie && ie_version >= 9);

// Optimize some code when these features are not used.
var sawReadOnlySpans = false, sawCollapsedSpans = false;

// EDITOR CONSTRUCTOR

// A CodeMirror instance represents an editor. This is the object
// that user code is usually dealing with.

function CodeMirror(place, options) {
  if (!(this instanceof CodeMirror)) return new CodeMirror(place, options);

  this.options = options = options || {};
  // Determine effective options based on given values and defaults.
  copyObj(defaults, options, false);
  setGuttersForLineNumbers(options);

  var doc = options.value;
  if (typeof doc == "string") doc = new Doc(doc, options.mode);
  this.doc = doc;

  var display = this.display = new Display(place, doc);
  display.wrapper.CodeMirror = this;
  updateGutters(this);
  themeChanged(this);
  if (options.lineWrapping)
    this.display.wrapper.className += " CodeMirror-wrap";
  if (options.autofocus && !mobile) focusInput(this);

  this.state = {
    keyMaps: [],  // stores maps added by addKeyMap
    overlays: [], // highlighting overlays, as added by addOverlay
    modeGen: 0,   // bumped when mode/overlay changes, used to invalidate highlighting info
    overwrite: false, focused: false,
    suppressEdits: false, // used to disable editing during key handlers when in readOnly mode
    pasteIncoming: false, cutIncoming: false, // help recognize paste/cut edits in readInput
    draggingText: false,
    highlight: new Delayed() // stores highlight worker timeout
  };

  // Override magic textarea content restore that IE sometimes does
  // on our hidden textarea on reload
  if (ie && ie_version < 11) setTimeout(bind(resetInput, this, true), 20);

  registerEventHandlers(this);
  ensureGlobalHandlers();

  var cm = this;
  runInOp(this, function() {
    cm.curOp.forceUpdate = true;
    attachDoc(cm, doc);

    if ((options.autofocus && !mobile) || activeElt() == display.input)
      setTimeout(bind(onFocus, cm), 20);
    else
      onBlur(cm);

    for (var opt in optionHandlers) if (optionHandlers.hasOwnProperty(opt))
      optionHandlers[opt](cm, options[opt], Init);
    maybeUpdateLineNumberWidth(cm);
    for (var i = 0; i < initHooks.length; ++i) initHooks[i](cm);
  });
}

// DISPLAY CONSTRUCTOR

// The display handles the DOM integration, both for input reading
// and content drawing. It holds references to DOM nodes and
// display-related state.

function Display(place, doc) {
  var d = this;

  // The semihidden textarea that is focused when the editor is
  // focused, and receives input.
  var input = d.input = elt("textarea", null, null, "position: absolute; padding: 0; width: 1px; height: 1em; outline: none");
  // The textarea is kept positioned near the cursor to prevent the
  // fact that it'll be scrolled into view on input from scrolling
  // our fake cursor out of view. On webkit, when wrap=off, paste is
  // very slow. So make the area wide instead.
  if (webkit) input.style.width = "1000px";
  else input.setAttribute("wrap", "off");
  // If border: 0; -- iOS fails to open keyboard (issue #1287)
  if (ios) input.style.border = "1px solid black";
  input.setAttribute("autocorrect", "off"); input.setAttribute("autocapitalize", "off"); input.setAttribute("spellcheck", "false");

  // Wraps and hides input textarea
  d.inputDiv = elt("div", [input], null, "overflow: hidden; position: relative; width: 3px; height: 0px;");
  // The fake scrollbar elements.
  d.scrollbarH = elt("div", [elt("div", null, null, "height: 100%; min-height: 1px")], "CodeMirror-hscrollbar");
  d.scrollbarV = elt("div", [elt("div", null, null, "min-width: 1px")], "CodeMirror-vscrollbar");
  // Covers bottom-right square when both scrollbars are present.
  d.scrollbarFiller = elt("div", null, "CodeMirror-scrollbar-filler");
  // Covers bottom of gutter when coverGutterNextToScrollbar is on
  // and h scrollbar is present.
  d.gutterFiller = elt("div", null, "CodeMirror-gutter-filler");
  // Will contain the actual code, positioned to cover the viewport.
  d.lineDiv = elt("div", null, "CodeMirror-code");
  // Elements are added to these to represent selection and cursors.
  d.selectionDiv = elt("div", null, null, "position: relative; z-index: 1");
  d.cursorDiv = elt("div", null, "CodeMirror-cursors");
  // A visibility: hidden element used to find the size of things.
  d.measure = elt("div", null, "CodeMirror-measure");
  // When lines outside of the viewport are measured, they are drawn in this.
  d.lineMeasure = elt("div", null, "CodeMirror-measure");
  // Wraps everything that needs to exist inside the vertically-padded coordinate system
  d.lineSpace = elt("div", [d.measure, d.lineMeasure, d.selectionDiv, d.cursorDiv, d.lineDiv],
                    null, "position: relative; outline: none");
  // Moved around its parent to cover visible view.
  d.mover = elt("div", [elt("div", [d.lineSpace], "CodeMirror-lines")], null, "position: relative");
  // Set to the height of the document, allowing scrolling.
  d.sizer = elt("div", [d.mover], "CodeMirror-sizer");
  // Behavior of elts with overflow: auto and padding is
  // inconsistent across browsers. This is used to ensure the
  // scrollable area is big enough.
  d.heightForcer = elt("div", null, null, "position: absolute; height: " + scrollerCutOff + "px; width: 1px;");
  // Will contain the gutters, if any.
  d.gutters = elt("div", null, "CodeMirror-gutters");
  d.lineGutter = null;
  // Actual scrollable element.
  d.scroller = elt("div", [d.sizer, d.heightForcer, d.gutters], "CodeMirror-scroll");
  d.scroller.setAttribute("tabIndex", "-1");
  // The element in which the editor lives.
  d.wrapper = elt("div", [d.inputDiv, d.scrollbarH, d.scrollbarV,
                          d.scrollbarFiller, d.gutterFiller, d.scroller], "CodeMirror");

  // Work around IE7 z-index bug (not perfect, hence IE7 not really being supported)
  if (ie && ie_version < 8) { d.gutters.style.zIndex = -1; d.scroller.style.paddingRight = 0; }
  // Needed to hide big blue blinking cursor on Mobile Safari
  if (ios) input.style.width = "0px";
  if (!webkit) d.scroller.draggable = true;
  // Needed to handle Tab key in KHTML
  if (khtml) { d.inputDiv.style.height = "1px"; d.inputDiv.style.position = "absolute"; }
  // Need to set a minimum width to see the scrollbar on IE7 (but must not set it on IE8).
  if (ie && ie_version < 8) d.scrollbarH.style.minHeight = d.scrollbarV.style.minWidth = "18px";

  if (place.appendChild) place.appendChild(d.wrapper);
  else place(d.wrapper);

  // Current rendered range (may be bigger than the view window).
  d.viewFrom = d.viewTo = doc.first;
  // Information about the rendered lines.
  d.view = [];
  // Holds info about a single rendered line when it was rendered
  // for measurement, while not in view.
  d.externalMeasured = null;
  // Empty space (in pixels) above the view
  d.viewOffset = 0;
  d.lastSizeC = 0;
  d.updateLineNumbers = null;

  // Used to only resize the line number gutter when necessary (when
  // the amount of lines crosses a boundary that makes its width change)
  d.lineNumWidth = d.lineNumInnerWidth = d.lineNumChars = null;
  // See readInput and resetInput
  d.prevInput = "";
  // Set to true when a non-horizontal-scrolling line widget is
  // added. As an optimization, line widget aligning is skipped when
  // this is false.
  d.alignWidgets = false;
  // Flag that indicates whether we expect input to appear real soon
  // now (after some event like 'keypress' or 'input') and are
  // polling intensively.
  d.pollingFast = false;
  // Self-resetting timeout for the poller
  d.poll = new Delayed();

  d.cachedCharWidth = d.cachedTextHeight = d.cachedPaddingH = null;

  // Tracks when resetInput has punted to just putting a short
  // string into the textarea instead of the full selection.
  d.inaccurateSelection = false;

  // Tracks the maximum line length so that the horizontal scrollbar
  // can be kept static when scrolling.
  d.maxLine = null;
  d.maxLineLength = 0;
  d.maxLineChanged = false;

  // Used for measuring wheel scrolling granularity
  d.wheelDX = d.wheelDY = d.wheelStartX = d.wheelStartY = null;

  // True when shift is held down.
  d.shift = false;

  // Used to track whether anything happened since the context menu
  // was opened.
  d.selForContextMenu = null;
}

// STATE UPDATES

// Used to get the editor into a consistent state again when options change.

function loadMode(cm) {
  cm.doc.mode = CodeMirror.getMode(cm.options, cm.doc.modeOption);
  resetModeState(cm);
}

function resetModeState(cm) {
  cm.doc.iter(function(line) {
    if (line.stateAfter) line.stateAfter = null;
    if (line.styles) line.styles = null;
  });
  cm.doc.frontier = cm.doc.first;
  startWorker(cm, 100);
  cm.state.modeGen++;
  if (cm.curOp) regChange(cm);
}

function wrappingChanged(cm) {
  if (cm.options.lineWrapping) {
    addClass(cm.display.wrapper, "CodeMirror-wrap");
    cm.display.sizer.style.minWidth = "";
  } else {
    rmClass(cm.display.wrapper, "CodeMirror-wrap");
    findMaxLine(cm);
  }
  estimateLineHeights(cm);
  regChange(cm);
  clearCaches(cm);
  setTimeout(function(){updateScrollbars(cm);}, 100);
}

// Returns a function that estimates the height of a line, to use as
// first approximation until the line becomes visible (and is thus
// properly measurable).
function estimateHeight(cm) {
  var th = textHeight(cm.display), wrapping = cm.options.lineWrapping;
  var perLine = wrapping && Math.max(5, cm.display.scroller.clientWidth / charWidth(cm.display) - 3);
  return function(line) {
    if (lineIsHidden(cm.doc, line)) return 0;

    var widgetsHeight = 0;
    if (line.widgets) for (var i = 0; i < line.widgets.length; i++) {
      if (line.widgets[i].height) widgetsHeight += line.widgets[i].height;
    }

    if (wrapping)
      return widgetsHeight + (Math.ceil(line.text.length / perLine) || 1) * th;
    else
      return widgetsHeight + th;
  };
}

function estimateLineHeights(cm) {
  var doc = cm.doc, est = estimateHeight(cm);
  doc.iter(function(line) {
    var estHeight = est(line);
    if (estHeight != line.height) updateLineHeight(line, estHeight);
  });
}

function keyMapChanged(cm) {
  var map = keyMap[cm.options.keyMap], style = map.style;
  cm.display.wrapper.className = cm.display.wrapper.className.replace(/\s*cm-keymap-\S+/g, "") +
    (style ? " cm-keymap-" + style : "");
}

function themeChanged(cm) {
  cm.display.wrapper.className = cm.display.wrapper.className.replace(/\s*cm-s-\S+/g, "") +
    cm.options.theme.replace(/(^|\s)\s*/g, " cm-s-");
  clearCaches(cm);
}

function guttersChanged(cm) {
  updateGutters(cm);
  regChange(cm);
  setTimeout(function(){alignHorizontally(cm);}, 20);
}

// Rebuild the gutter elements, ensure the margin to the left of the
// code matches their width.
function updateGutters(cm) {
  var gutters = cm.display.gutters, specs = cm.options.gutters;
  removeChildren(gutters);
  for (var i = 0; i < specs.length; ++i) {
    var gutterClass = specs[i];
    var gElt = gutters.appendChild(elt("div", null, "CodeMirror-gutter " + gutterClass));
    if (gutterClass == "CodeMirror-linenumbers") {
      cm.display.lineGutter = gElt;
      gElt.style.width = (cm.display.lineNumWidth || 1) + "px";
    }
  }
  gutters.style.display = i ? "" : "none";
  updateGutterSpace(cm);
}

function updateGutterSpace(cm) {
  var width = cm.display.gutters.offsetWidth;
  cm.display.sizer.style.marginLeft = width + "px";
  cm.display.scrollbarH.style.left = cm.options.fixedGutter ? width + "px" : 0;
}

// Compute the character length of a line, taking into account
// collapsed ranges (see markText) that might hide parts, and join
// other lines onto it.
function lineLength(line) {
  if (line.height == 0) return 0;
  var len = line.text.length, merged, cur = line;
  while (merged = collapsedSpanAtStart(cur)) {
    var found = merged.find(0, true);
    cur = found.from.line;
    len += found.from.ch - found.to.ch;
  }
  cur = line;
  while (merged = collapsedSpanAtEnd(cur)) {
    var found = merged.find(0, true);
    len -= cur.text.length - found.from.ch;
    cur = found.to.line;
    len += cur.text.length - found.to.ch;
  }
  return len;
}

// Find the longest line in the document.
function findMaxLine(cm) {
  var d = cm.display, doc = cm.doc;
  d.maxLine = getLine(doc, doc.first);
  d.maxLineLength = lineLength(d.maxLine);
  d.maxLineChanged = true;
  doc.iter(function(line) {
    var len = lineLength(line);
    if (len > d.maxLineLength) {
      d.maxLineLength = len;
      d.maxLine = line;
    }
  });
}

// Make sure the gutters options contains the element
// "CodeMirror-linenumbers" when the lineNumbers option is true.
function setGuttersForLineNumbers(options) {
  var found = indexOf(options.gutters, "CodeMirror-linenumbers");
  if (found == -1 && options.lineNumbers) {
    options.gutters = options.gutters.concat(["CodeMirror-linenumbers"]);
  } else if (found > -1 && !options.lineNumbers) {
    options.gutters = options.gutters.slice(0);
    options.gutters.splice(found, 1);
  }
}

// SCROLLBARS

function hScrollbarTakesSpace(cm) {
  return cm.display.scroller.clientHeight - cm.display.wrapper.clientHeight < scrollerCutOff - 3;
}

// Prepare DOM reads needed to update the scrollbars. Done in one
// shot to minimize update/measure roundtrips.
function measureForScrollbars(cm) {
  var scroll = cm.display.scroller;
  return {
    clientHeight: scroll.clientHeight,
    barHeight: cm.display.scrollbarV.clientHeight,
    scrollWidth: scroll.scrollWidth, clientWidth: scroll.clientWidth,
    hScrollbarTakesSpace: hScrollbarTakesSpace(cm),
    barWidth: cm.display.scrollbarH.clientWidth,
    docHeight: Math.round(cm.doc.height + paddingVert(cm.display))
  };
}

// Re-synchronize the fake scrollbars with the actual size of the
// content.
function updateScrollbars(cm, measure) {
  if (!measure) measure = measureForScrollbars(cm);
  var d = cm.display, sWidth = scrollbarWidth(d.measure);
  var scrollHeight = measure.docHeight + scrollerCutOff;
  var needsH = measure.scrollWidth > measure.clientWidth;
  if (needsH && measure.scrollWidth <= measure.clientWidth + 1 &&
      sWidth > 0 && !measure.hScrollbarTakesSpace)
    needsH = false; // (Issue #2562)
  var needsV = scrollHeight > measure.clientHeight;

  if (needsV) {
    d.scrollbarV.style.display = "block";
    d.scrollbarV.style.bottom = needsH ? sWidth + "px" : "0";
    // A bug in IE8 can cause this value to be negative, so guard it.
    d.scrollbarV.firstChild.style.height =
      Math.max(0, scrollHeight - measure.clientHeight + (measure.barHeight || d.scrollbarV.clientHeight)) + "px";
  } else {
    d.scrollbarV.style.display = "";
    d.scrollbarV.firstChild.style.height = "0";
  }
  if (needsH) {
    d.scrollbarH.style.display = "block";
    d.scrollbarH.style.right = needsV ? sWidth + "px" : "0";
    d.scrollbarH.firstChild.style.width =
      (measure.scrollWidth - measure.clientWidth + (measure.barWidth || d.scrollbarH.clientWidth)) + "px";
  } else {
    d.scrollbarH.style.display = "";
    d.scrollbarH.firstChild.style.width = "0";
  }
  if (needsH && needsV) {
    d.scrollbarFiller.style.display = "block";
    d.scrollbarFiller.style.height = d.scrollbarFiller.style.width = sWidth + "px";
  } else d.scrollbarFiller.style.display = "";
  if (needsH && cm.options.coverGutterNextToScrollbar && cm.options.fixedGutter) {
    d.gutterFiller.style.display = "block";
    d.gutterFiller.style.height = sWidth + "px";
    d.gutterFiller.style.width = d.gutters.offsetWidth + "px";
  } else d.gutterFiller.style.display = "";

  if (!cm.state.checkedOverlayScrollbar && measure.clientHeight > 0) {
    if (sWidth === 0) {
      var w = mac && !mac_geMountainLion ? "12px" : "18px";
      d.scrollbarV.style.minWidth = d.scrollbarH.style.minHeight = w;
      var barMouseDown = function(e) {
        if (e_target(e) != d.scrollbarV && e_target(e) != d.scrollbarH)
          operation(cm, onMouseDown)(e);
      };
      on(d.scrollbarV, "mousedown", barMouseDown);
      on(d.scrollbarH, "mousedown", barMouseDown);
    }
    cm.state.checkedOverlayScrollbar = true;
  }
}

// Compute the lines that are visible in a given viewport (defaults
// the the current scroll position). viewport may contain top,
// height, and ensure (see op.scrollToPos) properties.
function visibleLines(display, doc, viewport) {
  var top = viewport && viewport.top != null ? Math.max(0, viewport.top) : display.scroller.scrollTop;
  top = Math.floor(top - paddingTop(display));
  var bottom = viewport && viewport.bottom != null ? viewport.bottom : top + display.wrapper.clientHeight;

  var from = lineAtHeight(doc, top), to = lineAtHeight(doc, bottom);
  // Ensure is a {from: {line, ch}, to: {line, ch}} object, and
  // forces those lines into the viewport (if possible).
  if (viewport && viewport.ensure) {
    var ensureFrom = viewport.ensure.from.line, ensureTo = viewport.ensure.to.line;
    if (ensureFrom < from)
      return {from: ensureFrom,
              to: lineAtHeight(doc, heightAtLine(getLine(doc, ensureFrom)) + display.wrapper.clientHeight)};
    if (Math.min(ensureTo, doc.lastLine()) >= to)
      return {from: lineAtHeight(doc, heightAtLine(getLine(doc, ensureTo)) - display.wrapper.clientHeight),
              to: ensureTo};
  }
  return {from: from, to: Math.max(to, from + 1)};
}

// LINE NUMBERS

// Re-align line numbers and gutter marks to compensate for
// horizontal scrolling.
function alignHorizontally(cm) {
  var display = cm.display, view = display.view;
  if (!display.alignWidgets && (!display.gutters.firstChild || !cm.options.fixedGutter)) return;
  var comp = compensateForHScroll(display) - display.scroller.scrollLeft + cm.doc.scrollLeft;
  var gutterW = display.gutters.offsetWidth, left = comp + "px";
  for (var i = 0; i < view.length; i++) if (!view[i].hidden) {
    if (cm.options.fixedGutter && view[i].gutter)
      view[i].gutter.style.left = left;
    var align = view[i].alignable;
    if (align) for (var j = 0; j < align.length; j++)
      align[j].style.left = left;
  }
  if (cm.options.fixedGutter)
    display.gutters.style.left = (comp + gutterW) + "px";
}

// Used to ensure that the line number gutter is still the right
// size for the current document size. Returns true when an update
// is needed.
function maybeUpdateLineNumberWidth(cm) {
  if (!cm.options.lineNumbers) return false;
  var doc = cm.doc, last = lineNumberFor(cm.options, doc.first + doc.size - 1), display = cm.display;
  if (last.length != display.lineNumChars) {
    var test = display.measure.appendChild(elt("div", [elt("div", last)],
                                               "CodeMirror-linenumber CodeMirror-gutter-elt"));
    var innerW = test.firstChild.offsetWidth, padding = test.offsetWidth - innerW;
    display.lineGutter.style.width = "";
    display.lineNumInnerWidth = Math.max(innerW, display.lineGutter.offsetWidth - padding);
    display.lineNumWidth = display.lineNumInnerWidth + padding;
    display.lineNumChars = display.lineNumInnerWidth ? last.length : -1;
    display.lineGutter.style.width = display.lineNumWidth + "px";
    updateGutterSpace(cm);
    return true;
  }
  return false;
}

function lineNumberFor(options, i) {
  return String(options.lineNumberFormatter(i + options.firstLineNumber));
}

// Computes display.scroller.scrollLeft + display.gutters.offsetWidth,
// but using getBoundingClientRect to get a sub-pixel-accurate
// result.
function compensateForHScroll(display) {
  return display.scroller.getBoundingClientRect().left - display.sizer.getBoundingClientRect().left;
}

// DISPLAY DRAWING

function DisplayUpdate(cm, viewport, force) {
  var display = cm.display;

  this.viewport = viewport;
  // Store some values that we'll need later (but don't want to force a relayout for)
  this.visible = visibleLines(display, cm.doc, viewport);
  this.editorIsHidden = !display.wrapper.offsetWidth;
  this.wrapperHeight = display.wrapper.clientHeight;
  this.oldViewFrom = display.viewFrom; this.oldViewTo = display.viewTo;
  this.oldScrollerWidth = display.scroller.clientWidth;
  this.force = force;
  this.dims = getDimensions(cm);
}

// Does the actual updating of the line display. Bails out
// (returning false) when there is nothing to be done and forced is
// false.
function updateDisplayIfNeeded(cm, update) {
  var display = cm.display, doc = cm.doc;
  if (update.editorIsHidden) {
    resetView(cm);
    return false;
  }

  // Bail out if the visible area is already rendered and nothing changed.
  if (!update.force &&
      update.visible.from >= display.viewFrom && update.visible.to <= display.viewTo &&
      (display.updateLineNumbers == null || display.updateLineNumbers >= display.viewTo) &&
      countDirtyView(cm) == 0)
    return false;

  if (maybeUpdateLineNumberWidth(cm)) {
    resetView(cm);
    update.dims = getDimensions(cm);
  }

  // Compute a suitable new viewport (from & to)
  var end = doc.first + doc.size;
  var from = Math.max(update.visible.from - cm.options.viewportMargin, doc.first);
  var to = Math.min(end, update.visible.to + cm.options.viewportMargin);
  if (display.viewFrom < from && from - display.viewFrom < 20) from = Math.max(doc.first, display.viewFrom);
  if (display.viewTo > to && display.viewTo - to < 20) to = Math.min(end, display.viewTo);
  if (sawCollapsedSpans) {
    from = visualLineNo(cm.doc, from);
    to = visualLineEndNo(cm.doc, to);
  }

  var different = from != display.viewFrom || to != display.viewTo ||
    display.lastSizeC != update.wrapperHeight;
  adjustView(cm, from, to);

  display.viewOffset = heightAtLine(getLine(cm.doc, display.viewFrom));
  // Position the mover div to align with the current scroll position
  cm.display.mover.style.top = display.viewOffset + "px";

  var toUpdate = countDirtyView(cm);
  if (!different && toUpdate == 0 && !update.force &&
      (display.updateLineNumbers == null || display.updateLineNumbers >= display.viewTo))
    return false;

  // For big changes, we hide the enclosing element during the
  // update, since that speeds up the operations on most browsers.
  var focused = activeElt();
  if (toUpdate > 4) display.lineDiv.style.display = "none";
  patchDisplay(cm, display.updateLineNumbers, update.dims);
  if (toUpdate > 4) display.lineDiv.style.display = "";
  // There might have been a widget with a focused element that got
  // hidden or updated, if so re-focus it.
  if (focused && activeElt() != focused && focused.offsetHeight) focused.focus();

  // Prevent selection and cursors from interfering with the scroll
  // width.
  removeChildren(display.cursorDiv);
  removeChildren(display.selectionDiv);

  if (different) {
    display.lastSizeC = update.wrapperHeight;
    startWorker(cm, 400);
  }

  display.updateLineNumbers = null;

  return true;
}

function postUpdateDisplay(cm, update) {
  var force = update.force, viewport = update.viewport;
  for (var first = true;; first = false) {
    if (first && cm.options.lineWrapping && update.oldScrollerWidth != cm.display.scroller.clientWidth) {
      force = true;
    } else {
      force = false;
      // Clip forced viewport to actual scrollable area.
      if (viewport && viewport.top != null)
        viewport = {top: Math.min(cm.doc.height + paddingVert(cm.display) - scrollerCutOff -
                                  cm.display.scroller.clientHeight, viewport.top)};
      // Updated line heights might result in the drawn area not
      // actually covering the viewport. Keep looping until it does.
      update.visible = visibleLines(cm.display, cm.doc, viewport);
      if (update.visible.from >= cm.display.viewFrom && update.visible.to <= cm.display.viewTo)
        break;
    }
    if (!updateDisplayIfNeeded(cm, update)) break;
    updateHeightsInViewport(cm);
    var barMeasure = measureForScrollbars(cm);
    updateSelection(cm);
    setDocumentHeight(cm, barMeasure);
    updateScrollbars(cm, barMeasure);
  }

  signalLater(cm, "update", cm);
  if (cm.display.viewFrom != update.oldViewFrom || cm.display.viewTo != update.oldViewTo)
    signalLater(cm, "viewportChange", cm, cm.display.viewFrom, cm.display.viewTo);
}

function updateDisplaySimple(cm, viewport) {
  var update = new DisplayUpdate(cm, viewport);
  if (updateDisplayIfNeeded(cm, update)) {
    updateHeightsInViewport(cm);
    postUpdateDisplay(cm, update);
    var barMeasure = measureForScrollbars(cm);
    updateSelection(cm);
    setDocumentHeight(cm, barMeasure);
    updateScrollbars(cm, barMeasure);
  }
}

function setDocumentHeight(cm, measure) {
  cm.display.sizer.style.minHeight = cm.display.heightForcer.style.top = measure.docHeight + "px";
  cm.display.gutters.style.height = Math.max(measure.docHeight, measure.clientHeight - scrollerCutOff) + "px";
}

function checkForWebkitWidthBug(cm, measure) {
  // Work around Webkit bug where it sometimes reserves space for a
  // non-existing phantom scrollbar in the scroller (Issue #2420)
  if (cm.display.sizer.offsetWidth + cm.display.gutters.offsetWidth < cm.display.scroller.clientWidth - 1) {
    cm.display.sizer.style.minHeight = cm.display.heightForcer.style.top = "0px";
    cm.display.gutters.style.height = measure.docHeight + "px";
  }
}

// Read the actual heights of the rendered lines, and update their
// stored heights to match.
function updateHeightsInViewport(cm) {
  var display = cm.display;
  var prevBottom = display.lineDiv.offsetTop;
  for (var i = 0; i < display.view.length; i++) {
    var cur = display.view[i], height;
    if (cur.hidden) continue;
    if (ie && ie_version < 8) {
      var bot = cur.node.offsetTop + cur.node.offsetHeight;
      height = bot - prevBottom;
      prevBottom = bot;
    } else {
      var box = cur.node.getBoundingClientRect();
      height = box.bottom - box.top;
    }
    var diff = cur.line.height - height;
    if (height < 2) height = textHeight(display);
    if (diff > .001 || diff < -.001) {
      updateLineHeight(cur.line, height);
      updateWidgetHeight(cur.line);
      if (cur.rest) for (var j = 0; j < cur.rest.length; j++)
        updateWidgetHeight(cur.rest[j]);
    }
  }
}

// Read and store the height of line widgets associated with the
// given line.
function updateWidgetHeight(line) {
  if (line.widgets) for (var i = 0; i < line.widgets.length; ++i)
    line.widgets[i].height = line.widgets[i].node.offsetHeight;
}

// Do a bulk-read of the DOM positions and sizes needed to draw the
// view, so that we don't interleave reading and writing to the DOM.
function getDimensions(cm) {
  var d = cm.display, left = {}, width = {};
  for (var n = d.gutters.firstChild, i = 0; n; n = n.nextSibling, ++i) {
    left[cm.options.gutters[i]] = n.offsetLeft;
    width[cm.options.gutters[i]] = n.offsetWidth;
  }
  return {fixedPos: compensateForHScroll(d),
          gutterTotalWidth: d.gutters.offsetWidth,
          gutterLeft: left,
          gutterWidth: width,
          wrapperWidth: d.wrapper.clientWidth};
}

// Sync the actual display DOM structure with display.view, removing
// nodes for lines that are no longer in view, and creating the ones
// that are not there yet, and updating the ones that are out of
// date.
function patchDisplay(cm, updateNumbersFrom, dims) {
  var display = cm.display, lineNumbers = cm.options.lineNumbers;
  var container = display.lineDiv, cur = container.firstChild;

  function rm(node) {
    var next = node.nextSibling;
    // Works around a throw-scroll bug in OS X Webkit
    if (webkit && mac && cm.display.currentWheelTarget == node)
      node.style.display = "none";
    else
      node.parentNode.removeChild(node);
    return next;
  }

  var view = display.view, lineN = display.viewFrom;
  // Loop over the elements in the view, syncing cur (the DOM nodes
  // in display.lineDiv) with the view as we go.
  for (var i = 0; i < view.length; i++) {
    var lineView = view[i];
    if (lineView.hidden) {
    } else if (!lineView.node) { // Not drawn yet
      var node = buildLineElement(cm, lineView, lineN, dims);
      container.insertBefore(node, cur);
    } else { // Already drawn
      while (cur != lineView.node) cur = rm(cur);
      var updateNumber = lineNumbers && updateNumbersFrom != null &&
        updateNumbersFrom <= lineN && lineView.lineNumber;
      if (lineView.changes) {
        if (indexOf(lineView.changes, "gutter") > -1) updateNumber = false;
        updateLineForChanges(cm, lineView, lineN, dims);
      }
      if (updateNumber) {
        removeChildren(lineView.lineNumber);
        lineView.lineNumber.appendChild(document.createTextNode(lineNumberFor(cm.options, lineN)));
      }
      cur = lineView.node.nextSibling;
    }
    lineN += lineView.size;
  }
  while (cur) cur = rm(cur);
}

// When an aspect of a line changes, a string is added to
// lineView.changes. This updates the relevant part of the line's
// DOM structure.
function updateLineForChanges(cm, lineView, lineN, dims) {
  for (var j = 0; j < lineView.changes.length; j++) {
    var type = lineView.changes[j];
    if (type == "text") updateLineText(cm, lineView);
    else if (type == "gutter") updateLineGutter(cm, lineView, lineN, dims);
    else if (type == "class") updateLineClasses(lineView);
    else if (type == "widget") updateLineWidgets(lineView, dims);
  }
  lineView.changes = null;
}

// Lines with gutter elements, widgets or a background class need to
// be wrapped, and have the extra elements added to the wrapper div
function ensureLineWrapped(lineView) {
  if (lineView.node == lineView.text) {
    lineView.node = elt("div", null, null, "position: relative");
    if (lineView.text.parentNode)
      lineView.text.parentNode.replaceChild(lineView.node, lineView.text);
    lineView.node.appendChild(lineView.text);
    if (ie && ie_version < 8) lineView.node.style.zIndex = 2;
  }
  return lineView.node;
}

function updateLineBackground(lineView) {
  var cls = lineView.bgClass ? lineView.bgClass + " " + (lineView.line.bgClass || "") : lineView.line.bgClass;
  if (cls) cls += " CodeMirror-linebackground";
  if (lineView.background) {
    if (cls) lineView.background.className = cls;
    else { lineView.background.parentNode.removeChild(lineView.background); lineView.background = null; }
  } else if (cls) {
    var wrap = ensureLineWrapped(lineView);
    lineView.background = wrap.insertBefore(elt("div", null, cls), wrap.firstChild);
  }
}

// Wrapper around buildLineContent which will reuse the structure
// in display.externalMeasured when possible.
function getLineContent(cm, lineView) {
  var ext = cm.display.externalMeasured;
  if (ext && ext.line == lineView.line) {
    cm.display.externalMeasured = null;
    lineView.measure = ext.measure;
    return ext.built;
  }
  return buildLineContent(cm, lineView);
}

// Redraw the line's text. Interacts with the background and text
// classes because the mode may output tokens that influence these
// classes.
function updateLineText(cm, lineView) {
  var cls = lineView.text.className;
  var built = getLineContent(cm, lineView);
  if (lineView.text == lineView.node) lineView.node = built.pre;
  lineView.text.parentNode.replaceChild(built.pre, lineView.text);
  lineView.text = built.pre;
  if (built.bgClass != lineView.bgClass || built.textClass != lineView.textClass) {
    lineView.bgClass = built.bgClass;
    lineView.textClass = built.textClass;
    updateLineClasses(lineView);
  } else if (cls) {
    lineView.text.className = cls;
  }
}

function updateLineClasses(lineView) {
  updateLineBackground(lineView);
  if (lineView.line.wrapClass)
    ensureLineWrapped(lineView).className = lineView.line.wrapClass;
  else if (lineView.node != lineView.text)
    lineView.node.className = "";
  var textClass = lineView.textClass ? lineView.textClass + " " + (lineView.line.textClass || "") : lineView.line.textClass;
  lineView.text.className = textClass || "";
}

function updateLineGutter(cm, lineView, lineN, dims) {
  if (lineView.gutter) {
    lineView.node.removeChild(lineView.gutter);
    lineView.gutter = null;
  }
  var markers = lineView.line.gutterMarkers;
  if (cm.options.lineNumbers || markers) {
    var wrap = ensureLineWrapped(lineView);
    var gutterWrap = lineView.gutter =
      wrap.insertBefore(elt("div", null, "CodeMirror-gutter-wrapper", "position: absolute; left: " +
                            (cm.options.fixedGutter ? dims.fixedPos : -dims.gutterTotalWidth) + "px"),
                        lineView.text);
    if (cm.options.lineNumbers && (!markers || !markers["CodeMirror-linenumbers"]))
      lineView.lineNumber = gutterWrap.appendChild(
        elt("div", lineNumberFor(cm.options, lineN),
            "CodeMirror-linenumber CodeMirror-gutter-elt",
            "left: " + dims.gutterLeft["CodeMirror-linenumbers"] + "px; width: "
            + cm.display.lineNumInnerWidth + "px"));
    if (markers) for (var k = 0; k < cm.options.gutters.length; ++k) {
      var id = cm.options.gutters[k], found = markers.hasOwnProperty(id) && markers[id];
      if (found)
        gutterWrap.appendChild(elt("div", [found], "CodeMirror-gutter-elt", "left: " +
                                   dims.gutterLeft[id] + "px; width: " + dims.gutterWidth[id] + "px"));
    }
  }
}

function updateLineWidgets(lineView, dims) {
  if (lineView.alignable) lineView.alignable = null;
  for (var node = lineView.node.firstChild, next; node; node = next) {
    var next = node.nextSibling;
    if (node.className == "CodeMirror-linewidget")
      lineView.node.removeChild(node);
  }
  insertLineWidgets(lineView, dims);
}

// Build a line's DOM representation from scratch
function buildLineElement(cm, lineView, lineN, dims) {
  var built = getLineContent(cm, lineView);
  lineView.text = lineView.node = built.pre;
  if (built.bgClass) lineView.bgClass = built.bgClass;
  if (built.textClass) lineView.textClass = built.textClass;

  updateLineClasses(lineView);
  updateLineGutter(cm, lineView, lineN, dims);
  insertLineWidgets(lineView, dims);
  return lineView.node;
}

// A lineView may contain multiple logical lines (when merged by
// collapsed spans). The widgets for all of them need to be drawn.
function insertLineWidgets(lineView, dims) {
  insertLineWidgetsFor(lineView.line, lineView, dims, true);
  if (lineView.rest) for (var i = 0; i < lineView.rest.length; i++)
    insertLineWidgetsFor(lineView.rest[i], lineView, dims, false);
}

function insertLineWidgetsFor(line, lineView, dims, allowAbove) {
  if (!line.widgets) return;
  var wrap = ensureLineWrapped(lineView);
  for (var i = 0, ws = line.widgets; i < ws.length; ++i) {
    var widget = ws[i], node = elt("div", [widget.node], "CodeMirror-linewidget");
    if (!widget.handleMouseEvents) node.ignoreEvents = true;
    positionLineWidget(widget, node, lineView, dims);
    if (allowAbove && widget.above)
      wrap.insertBefore(node, lineView.gutter || lineView.text);
    else
      wrap.appendChild(node);
    signalLater(widget, "redraw");
  }
}

function positionLineWidget(widget, node, lineView, dims) {
  if (widget.noHScroll) {
    (lineView.alignable || (lineView.alignable = [])).push(node);
    var width = dims.wrapperWidth;
    node.style.left = dims.fixedPos + "px";
    if (!widget.coverGutter) {
      width -= dims.gutterTotalWidth;
      node.style.paddingLeft = dims.gutterTotalWidth + "px";
    }
    node.style.width = width + "px";
  }
  if (widget.coverGutter) {
    node.style.zIndex = 5;
    node.style.position = "relative";
    if (!widget.noHScroll) node.style.marginLeft = -dims.gutterTotalWidth + "px";
  }
}

// POSITION OBJECT

// A Pos instance represents a position within the text.
var Pos = CodeMirror.Pos = function(line, ch) {
  if (!(this instanceof Pos)) return new Pos(line, ch);
  this.line = line; this.ch = ch;
};

// Compare two positions, return 0 if they are the same, a negative
// number when a is less, and a positive number otherwise.
var cmp = CodeMirror.cmpPos = function(a, b) { return a.line - b.line || a.ch - b.ch; };

function copyPos(x) {return Pos(x.line, x.ch);}
function maxPos(a, b) { return cmp(a, b) < 0 ? b : a; }
function minPos(a, b) { return cmp(a, b) < 0 ? a : b; }

// SELECTION / CURSOR

// Selection objects are immutable. A new one is created every time
// the selection changes. A selection is one or more non-overlapping
// (and non-touching) ranges, sorted, and an integer that indicates
// which one is the primary selection (the one that's scrolled into
// view, that getCursor returns, etc).
function Selection(ranges, primIndex) {
  this.ranges = ranges;
  this.primIndex = primIndex;
}

Selection.prototype = {
  primary: function() { return this.ranges[this.primIndex]; },
  equals: function(other) {
    if (other == this) return true;
    if (other.primIndex != this.primIndex || other.ranges.length != this.ranges.length) return false;
    for (var i = 0; i < this.ranges.length; i++) {
      var here = this.ranges[i], there = other.ranges[i];
      if (cmp(here.anchor, there.anchor) != 0 || cmp(here.head, there.head) != 0) return false;
    }
    return true;
  },
  deepCopy: function() {
    for (var out = [], i = 0; i < this.ranges.length; i++)
      out[i] = new Range(copyPos(this.ranges[i].anchor), copyPos(this.ranges[i].head));
    return new Selection(out, this.primIndex);
  },
  somethingSelected: function() {
    for (var i = 0; i < this.ranges.length; i++)
      if (!this.ranges[i].empty()) return true;
    return false;
  },
  contains: function(pos, end) {
    if (!end) end = pos;
    for (var i = 0; i < this.ranges.length; i++) {
      var range = this.ranges[i];
      if (cmp(end, range.from()) >= 0 && cmp(pos, range.to()) <= 0)
        return i;
    }
    return -1;
  }
};

function Range(anchor, head) {
  this.anchor = anchor; this.head = head;
}

Range.prototype = {
  from: function() { return minPos(this.anchor, this.head); },
  to: function() { return maxPos(this.anchor, this.head); },
  empty: function() {
    return this.head.line == this.anchor.line && this.head.ch == this.anchor.ch;
  }
};

// Take an unsorted, potentially overlapping set of ranges, and
// build a selection out of it. 'Consumes' ranges array (modifying
// it).
function normalizeSelection(ranges, primIndex) {
  var prim = ranges[primIndex];
  ranges.sort(function(a, b) { return cmp(a.from(), b.from()); });
  primIndex = indexOf(ranges, prim);
  for (var i = 1; i < ranges.length; i++) {
    var cur = ranges[i], prev = ranges[i - 1];
    if (cmp(prev.to(), cur.from()) >= 0) {
      var from = minPos(prev.from(), cur.from()), to = maxPos(prev.to(), cur.to());
      var inv = prev.empty() ? cur.from() == cur.head : prev.from() == prev.head;
      if (i <= primIndex) --primIndex;
      ranges.splice(--i, 2, new Range(inv ? to : from, inv ? from : to));
    }
  }
  return new Selection(ranges, primIndex);
}

function simpleSelection(anchor, head) {
  return new Selection([new Range(anchor, head || anchor)], 0);
}

// Most of the external API clips given positions to make sure they
// actually exist within the document.
function clipLine(doc, n) {return Math.max(doc.first, Math.min(n, doc.first + doc.size - 1));}
function clipPos(doc, pos) {
  if (pos.line < doc.first) return Pos(doc.first, 0);
  var last = doc.first + doc.size - 1;
  if (pos.line > last) return Pos(last, getLine(doc, last).text.length);
  return clipToLen(pos, getLine(doc, pos.line).text.length);
}
function clipToLen(pos, linelen) {
  var ch = pos.ch;
  if (ch == null || ch > linelen) return Pos(pos.line, linelen);
  else if (ch < 0) return Pos(pos.line, 0);
  else return pos;
}
function isLine(doc, l) {return l >= doc.first && l < doc.first + doc.size;}
function clipPosArray(doc, array) {
  for (var out = [], i = 0; i < array.length; i++) out[i] = clipPos(doc, array[i]);
  return out;
}

// SELECTION UPDATES

// The 'scroll' parameter given to many of these indicated whether
// the new cursor position should be scrolled into view after
// modifying the selection.

// If shift is held or the extend flag is set, extends a range to
// include a given position (and optionally a second position).
// Otherwise, simply returns the range between the given positions.
// Used for cursor motion and such.
function extendRange(doc, range, head, other) {
  if (doc.cm && doc.cm.display.shift || doc.extend) {
    var anchor = range.anchor;
    if (other) {
      var posBefore = cmp(head, anchor) < 0;
      if (posBefore != (cmp(other, anchor) < 0)) {
        anchor = head;
        head = other;
      } else if (posBefore != (cmp(head, other) < 0)) {
        head = other;
      }
    }
    return new Range(anchor, head);
  } else {
    return new Range(other || head, head);
  }
}

// Extend the primary selection range, discard the rest.
function extendSelection(doc, head, other, options) {
  setSelection(doc, new Selection([extendRange(doc, doc.sel.primary(), head, other)], 0), options);
}

// Extend all selections (pos is an array of selections with length
// equal the number of selections)
function extendSelections(doc, heads, options) {
  for (var out = [], i = 0; i < doc.sel.ranges.length; i++)
    out[i] = extendRange(doc, doc.sel.ranges[i], heads[i], null);
  var newSel = normalizeSelection(out, doc.sel.primIndex);
  setSelection(doc, newSel, options);
}

// Updates a single range in the selection.
function replaceOneSelection(doc, i, range, options) {
  var ranges = doc.sel.ranges.slice(0);
  ranges[i] = range;
  setSelection(doc, normalizeSelection(ranges, doc.sel.primIndex), options);
}

// Reset the selection to a single range.
function setSimpleSelection(doc, anchor, head, options) {
  setSelection(doc, simpleSelection(anchor, head), options);
}

// Give beforeSelectionChange handlers a change to influence a
// selection update.
function filterSelectionChange(doc, sel) {
  var obj = {
    ranges: sel.ranges,
    update: function(ranges) {
      this.ranges = [];
      for (var i = 0; i < ranges.length; i++)
        this.ranges[i] = new Range(clipPos(doc, ranges[i].anchor),
                                   clipPos(doc, ranges[i].head));
    }
  };
  signal(doc, "beforeSelectionChange", doc, obj);
  if (doc.cm) signal(doc.cm, "beforeSelectionChange", doc.cm, obj);
  if (obj.ranges != sel.ranges) return normalizeSelection(obj.ranges, obj.ranges.length - 1);
  else return sel;
}

function setSelectionReplaceHistory(doc, sel, options) {
  var done = doc.history.done, last = lst(done);
  if (last && last.ranges) {
    done[done.length - 1] = sel;
    setSelectionNoUndo(doc, sel, options);
  } else {
    setSelection(doc, sel, options);
  }
}

// Set a new selection.
function setSelection(doc, sel, options) {
  setSelectionNoUndo(doc, sel, options);
  addSelectionToHistory(doc, doc.sel, doc.cm ? doc.cm.curOp.id : NaN, options);
}

function setSelectionNoUndo(doc, sel, options) {
  if (hasHandler(doc, "beforeSelectionChange") || doc.cm && hasHandler(doc.cm, "beforeSelectionChange"))
    sel = filterSelectionChange(doc, sel);

  var bias = options && options.bias ||
    (cmp(sel.primary().head, doc.sel.primary().head) < 0 ? -1 : 1);
  setSelectionInner(doc, skipAtomicInSelection(doc, sel, bias, true));

  if (!(options && options.scroll === false) && doc.cm)
    ensureCursorVisible(doc.cm);
}

function setSelectionInner(doc, sel) {
  if (sel.equals(doc.sel)) return;

  doc.sel = sel;

  if (doc.cm) {
    doc.cm.curOp.updateInput = doc.cm.curOp.selectionChanged = true;
    signalCursorActivity(doc.cm);
  }
  signalLater(doc, "cursorActivity", doc);
}

// Verify that the selection does not partially select any atomic
// marked ranges.
function reCheckSelection(doc) {
  setSelectionInner(doc, skipAtomicInSelection(doc, doc.sel, null, false), sel_dontScroll);
}

// Return a selection that does not partially select any atomic
// ranges.
function skipAtomicInSelection(doc, sel, bias, mayClear) {
  var out;
  for (var i = 0; i < sel.ranges.length; i++) {
    var range = sel.ranges[i];
    var newAnchor = skipAtomic(doc, range.anchor, bias, mayClear);
    var newHead = skipAtomic(doc, range.head, bias, mayClear);
    if (out || newAnchor != range.anchor || newHead != range.head) {
      if (!out) out = sel.ranges.slice(0, i);
      out[i] = new Range(newAnchor, newHead);
    }
  }
  return out ? normalizeSelection(out, sel.primIndex) : sel;
}

// Ensure a given position is not inside an atomic range.
function skipAtomic(doc, pos, bias, mayClear) {
  var flipped = false, curPos = pos;
  var dir = bias || 1;
  doc.cantEdit = false;
  search: for (;;) {
    var line = getLine(doc, curPos.line);
    if (line.markedSpans) {
      for (var i = 0; i < line.markedSpans.length; ++i) {
        var sp = line.markedSpans[i], m = sp.marker;
        if ((sp.from == null || (m.inclusiveLeft ? sp.from <= curPos.ch : sp.from < curPos.ch)) &&
            (sp.to == null || (m.inclusiveRight ? sp.to >= curPos.ch : sp.to > curPos.ch))) {
          if (mayClear) {
            signal(m, "beforeCursorEnter");
            if (m.explicitlyCleared) {
              if (!line.markedSpans) break;
              else {--i; continue;}
            }
          }
          if (!m.atomic) continue;
          var newPos = m.find(dir < 0 ? -1 : 1);
          if (cmp(newPos, curPos) == 0) {
            newPos.ch += dir;
            if (newPos.ch < 0) {
              if (newPos.line > doc.first) newPos = clipPos(doc, Pos(newPos.line - 1));
              else newPos = null;
            } else if (newPos.ch > line.text.length) {
              if (newPos.line < doc.first + doc.size - 1) newPos = Pos(newPos.line + 1, 0);
              else newPos = null;
            }
            if (!newPos) {
              if (flipped) {
                // Driven in a corner -- no valid cursor position found at all
                // -- try again *with* clearing, if we didn't already
                if (!mayClear) return skipAtomic(doc, pos, bias, true);
                // Otherwise, turn off editing until further notice, and return the start of the doc
                doc.cantEdit = true;
                return Pos(doc.first, 0);
              }
              flipped = true; newPos = pos; dir = -dir;
            }
          }
          curPos = newPos;
          continue search;
        }
      }
    }
    return curPos;
  }
}

// SELECTION DRAWING

// Redraw the selection and/or cursor
function drawSelection(cm) {
  var display = cm.display, doc = cm.doc, result = {};
  var curFragment = result.cursors = document.createDocumentFragment();
  var selFragment = result.selection = document.createDocumentFragment();

  for (var i = 0; i < doc.sel.ranges.length; i++) {
    var range = doc.sel.ranges[i];
    var collapsed = range.empty();
    if (collapsed || cm.options.showCursorWhenSelecting)
      drawSelectionCursor(cm, range, curFragment);
    if (!collapsed)
      drawSelectionRange(cm, range, selFragment);
  }

  // Move the hidden textarea near the cursor to prevent scrolling artifacts
  if (cm.options.moveInputWithCursor) {
    var headPos = cursorCoords(cm, doc.sel.primary().head, "div");
    var wrapOff = display.wrapper.getBoundingClientRect(), lineOff = display.lineDiv.getBoundingClientRect();
    result.teTop = Math.max(0, Math.min(display.wrapper.clientHeight - 10,
                                        headPos.top + lineOff.top - wrapOff.top));
    result.teLeft = Math.max(0, Math.min(display.wrapper.clientWidth - 10,
                                         headPos.left + lineOff.left - wrapOff.left));
  }

  return result;
}

function showSelection(cm, drawn) {
  removeChildrenAndAdd(cm.display.cursorDiv, drawn.cursors);
  removeChildrenAndAdd(cm.display.selectionDiv, drawn.selection);
  if (drawn.teTop != null) {
    cm.display.inputDiv.style.top = drawn.teTop + "px";
    cm.display.inputDiv.style.left = drawn.teLeft + "px";
  }
}

function updateSelection(cm) {
  showSelection(cm, drawSelection(cm));
}

// Draws a cursor for the given range
function drawSelectionCursor(cm, range, output) {
  var pos = cursorCoords(cm, range.head, "div", null, null, !cm.options.singleCursorHeightPerLine);

  var cursor = output.appendChild(elt("div", "\u00a0", "CodeMirror-cursor"));
  cursor.style.left = pos.left + "px";
  cursor.style.top = pos.top + "px";
  cursor.style.height = Math.max(0, pos.bottom - pos.top) * cm.options.cursorHeight + "px";

  if (pos.other) {
    // Secondary cursor, shown when on a 'jump' in bi-directional text
    var otherCursor = output.appendChild(elt("div", "\u00a0", "CodeMirror-cursor CodeMirror-secondarycursor"));
    otherCursor.style.display = "";
    otherCursor.style.left = pos.other.left + "px";
    otherCursor.style.top = pos.other.top + "px";
    otherCursor.style.height = (pos.other.bottom - pos.other.top) * .85 + "px";
  }
}

// Draws the given range as a highlighted selection
function drawSelectionRange(cm, range, output) {
  var display = cm.display, doc = cm.doc;
  var fragment = document.createDocumentFragment();
  var padding = paddingH(cm.display), leftSide = padding.left, rightSide = display.lineSpace.offsetWidth - padding.right;

  function add(left, top, width, bottom) {
    if (top < 0) top = 0;
    top = Math.round(top);
    bottom = Math.round(bottom);
    fragment.appendChild(elt("div", null, "CodeMirror-selected", "position: absolute; left: " + left +
                             "px; top: " + top + "px; width: " + (width == null ? rightSide - left : width) +
                             "px; height: " + (bottom - top) + "px"));
  }

  function drawForLine(line, fromArg, toArg) {
    var lineObj = getLine(doc, line);
    var lineLen = lineObj.text.length;
    var start, end;
    function coords(ch, bias) {
      return charCoords(cm, Pos(line, ch), "div", lineObj, bias);
    }

    iterateBidiSections(getOrder(lineObj), fromArg || 0, toArg == null ? lineLen : toArg, function(from, to, dir) {
      var leftPos = coords(from, "left"), rightPos, left, right;
      if (from == to) {
        rightPos = leftPos;
        left = right = leftPos.left;
      } else {
        rightPos = coords(to - 1, "right");
        if (dir == "rtl") { var tmp = leftPos; leftPos = rightPos; rightPos = tmp; }
        left = leftPos.left;
        right = rightPos.right;
      }
      if (fromArg == null && from == 0) left = leftSide;
      if (rightPos.top - leftPos.top > 3) { // Different lines, draw top part
        add(left, leftPos.top, null, leftPos.bottom);
        left = leftSide;
        if (leftPos.bottom < rightPos.top) add(left, leftPos.bottom, null, rightPos.top);
      }
      if (toArg == null && to == lineLen) right = rightSide;
      if (!start || leftPos.top < start.top || leftPos.top == start.top && leftPos.left < start.left)
        start = leftPos;
      if (!end || rightPos.bottom > end.bottom || rightPos.bottom == end.bottom && rightPos.right > end.right)
        end = rightPos;
      if (left < leftSide + 1) left = leftSide;
      add(left, rightPos.top, right - left, rightPos.bottom);
    });
    return {start: start, end: end};
  }

  var sFrom = range.from(), sTo = range.to();
  if (sFrom.line == sTo.line) {
    drawForLine(sFrom.line, sFrom.ch, sTo.ch);
  } else {
    var fromLine = getLine(doc, sFrom.line), toLine = getLine(doc, sTo.line);
    var singleVLine = visualLine(fromLine) == visualLine(toLine);
    var leftEnd = drawForLine(sFrom.line, sFrom.ch, singleVLine ? fromLine.text.length + 1 : null).end;
    var rightStart = drawForLine(sTo.line, singleVLine ? 0 : null, sTo.ch).start;
    if (singleVLine) {
      if (leftEnd.top < rightStart.top - 2) {
        add(leftEnd.right, leftEnd.top, null, leftEnd.bottom);
        add(leftSide, rightStart.top, rightStart.left, rightStart.bottom);
      } else {
        add(leftEnd.right, leftEnd.top, rightStart.left - leftEnd.right, leftEnd.bottom);
      }
    }
    if (leftEnd.bottom < rightStart.top)
      add(leftSide, leftEnd.bottom, null, rightStart.top);
  }

  output.appendChild(fragment);
}

// Cursor-blinking
function restartBlink(cm) {
  if (!cm.state.focused) return;
  var display = cm.display;
  clearInterval(display.blinker);
  var on = true;
  display.cursorDiv.style.visibility = "";
  if (cm.options.cursorBlinkRate > 0)
    display.blinker = setInterval(function() {
      display.cursorDiv.style.visibility = (on = !on) ? "" : "hidden";
    }, cm.options.cursorBlinkRate);
  else if (cm.options.cursorBlinkRate < 0)
    display.cursorDiv.style.visibility = "hidden";
}

// HIGHLIGHT WORKER

function startWorker(cm, time) {
  if (cm.doc.mode.startState && cm.doc.frontier < cm.display.viewTo)
    cm.state.highlight.set(time, bind(highlightWorker, cm));
}

function highlightWorker(cm) {
  var doc = cm.doc;
  if (doc.frontier < doc.first) doc.frontier = doc.first;
  if (doc.frontier >= cm.display.viewTo) return;
  var end = +new Date + cm.options.workTime;
  var state = copyState(doc.mode, getStateBefore(cm, doc.frontier));
  var changedLines = [];

  doc.iter(doc.frontier, Math.min(doc.first + doc.size, cm.display.viewTo + 500), function(line) {
    if (doc.frontier >= cm.display.viewFrom) { // Visible
      var oldStyles = line.styles;
      var highlighted = highlightLine(cm, line, state, true);
      line.styles = highlighted.styles;
      var oldCls = line.styleClasses, newCls = highlighted.classes;
      if (newCls) line.styleClasses = newCls;
      else if (oldCls) line.styleClasses = null;
      var ischange = !oldStyles || oldStyles.length != line.styles.length ||
        oldCls != newCls && (!oldCls || !newCls || oldCls.bgClass != newCls.bgClass || oldCls.textClass != newCls.textClass);
      for (var i = 0; !ischange && i < oldStyles.length; ++i) ischange = oldStyles[i] != line.styles[i];
      if (ischange) changedLines.push(doc.frontier);
      line.stateAfter = copyState(doc.mode, state);
    } else {
      processLine(cm, line.text, state);
      line.stateAfter = doc.frontier % 5 == 0 ? copyState(doc.mode, state) : null;
    }
    ++doc.frontier;
    if (+new Date > end) {
      startWorker(cm, cm.options.workDelay);
      return true;
    }
  });
  if (changedLines.length) runInOp(cm, function() {
    for (var i = 0; i < changedLines.length; i++)
      regLineChange(cm, changedLines[i], "text");
  });
}

// Finds the line to start with when starting a parse. Tries to
// find a line with a stateAfter, so that it can start with a
// valid state. If that fails, it returns the line with the
// smallest indentation, which tends to need the least context to
// parse correctly.
function findStartLine(cm, n, precise) {
  var minindent, minline, doc = cm.doc;
  var lim = precise ? -1 : n - (cm.doc.mode.innerMode ? 1000 : 100);
  for (var search = n; search > lim; --search) {
    if (search <= doc.first) return doc.first;
    var line = getLine(doc, search - 1);
    if (line.stateAfter && (!precise || search <= doc.frontier)) return search;
    var indented = countColumn(line.text, null, cm.options.tabSize);
    if (minline == null || minindent > indented) {
      minline = search - 1;
      minindent = indented;
    }
  }
  return minline;
}

function getStateBefore(cm, n, precise) {
  var doc = cm.doc, display = cm.display;
  if (!doc.mode.startState) return true;
  var pos = findStartLine(cm, n, precise), state = pos > doc.first && getLine(doc, pos-1).stateAfter;
  if (!state) state = startState(doc.mode);
  else state = copyState(doc.mode, state);
  doc.iter(pos, n, function(line) {
    processLine(cm, line.text, state);
    var save = pos == n - 1 || pos % 5 == 0 || pos >= display.viewFrom && pos < display.viewTo;
    line.stateAfter = save ? copyState(doc.mode, state) : null;
    ++pos;
  });
  if (precise) doc.frontier = pos;
  return state;
}

// POSITION MEASUREMENT

function paddingTop(display) {return display.lineSpace.offsetTop;}
function paddingVert(display) {return display.mover.offsetHeight - display.lineSpace.offsetHeight;}
function paddingH(display) {
  if (display.cachedPaddingH) return display.cachedPaddingH;
  var e = removeChildrenAndAdd(display.measure, elt("pre", "x"));
  var style = window.getComputedStyle ? window.getComputedStyle(e) : e.currentStyle;
  var data = {left: parseInt(style.paddingLeft), right: parseInt(style.paddingRight)};
  if (!isNaN(data.left) && !isNaN(data.right)) display.cachedPaddingH = data;
  return data;
}

// Ensure the lineView.wrapping.heights array is populated. This is
// an array of bottom offsets for the lines that make up a drawn
// line. When lineWrapping is on, there might be more than one
// height.
function ensureLineHeights(cm, lineView, rect) {
  var wrapping = cm.options.lineWrapping;
  var curWidth = wrapping && cm.display.scroller.clientWidth;
  if (!lineView.measure.heights || wrapping && lineView.measure.width != curWidth) {
    var heights = lineView.measure.heights = [];
    if (wrapping) {
      lineView.measure.width = curWidth;
      var rects = lineView.text.firstChild.getClientRects();
      for (var i = 0; i < rects.length - 1; i++) {
        var cur = rects[i], next = rects[i + 1];
        if (Math.abs(cur.bottom - next.bottom) > 2)
          heights.push((cur.bottom + next.top) / 2 - rect.top);
      }
    }
    heights.push(rect.bottom - rect.top);
  }
}

// Find a line map (mapping character offsets to text nodes) and a
// measurement cache for the given line number. (A line view might
// contain multiple lines when collapsed ranges are present.)
function mapFromLineView(lineView, line, lineN) {
  if (lineView.line == line)
    return {map: lineView.measure.map, cache: lineView.measure.cache};
  for (var i = 0; i < lineView.rest.length; i++)
    if (lineView.rest[i] == line)
      return {map: lineView.measure.maps[i], cache: lineView.measure.caches[i]};
  for (var i = 0; i < lineView.rest.length; i++)
    if (lineNo(lineView.rest[i]) > lineN)
      return {map: lineView.measure.maps[i], cache: lineView.measure.caches[i], before: true};
}

// Render a line into the hidden node display.externalMeasured. Used
// when measurement is needed for a line that's not in the viewport.
function updateExternalMeasurement(cm, line) {
  line = visualLine(line);
  var lineN = lineNo(line);
  var view = cm.display.externalMeasured = new LineView(cm.doc, line, lineN);
  view.lineN = lineN;
  var built = view.built = buildLineContent(cm, view);
  view.text = built.pre;
  removeChildrenAndAdd(cm.display.lineMeasure, built.pre);
  return view;
}

// Get a {top, bottom, left, right} box (in line-local coordinates)
// for a given character.
function measureChar(cm, line, ch, bias) {
  return measureCharPrepared(cm, prepareMeasureForLine(cm, line), ch, bias);
}

// Find a line view that corresponds to the given line number.
function findViewForLine(cm, lineN) {
  if (lineN >= cm.display.viewFrom && lineN < cm.display.viewTo)
    return cm.display.view[findViewIndex(cm, lineN)];
  var ext = cm.display.externalMeasured;
  if (ext && lineN >= ext.lineN && lineN < ext.lineN + ext.size)
    return ext;
}

// Measurement can be split in two steps, the set-up work that
// applies to the whole line, and the measurement of the actual
// character. Functions like coordsChar, that need to do a lot of
// measurements in a row, can thus ensure that the set-up work is
// only done once.
function prepareMeasureForLine(cm, line) {
  var lineN = lineNo(line);
  var view = findViewForLine(cm, lineN);
  if (view && !view.text)
    view = null;
  else if (view && view.changes)
    updateLineForChanges(cm, view, lineN, getDimensions(cm));
  if (!view)
    view = updateExternalMeasurement(cm, line);

  var info = mapFromLineView(view, line, lineN);
  return {
    line: line, view: view, rect: null,
    map: info.map, cache: info.cache, before: info.before,
    hasHeights: false
  };
}

// Given a prepared measurement object, measures the position of an
// actual character (or fetches it from the cache).
function measureCharPrepared(cm, prepared, ch, bias, varHeight) {
  if (prepared.before) ch = -1;
  var key = ch + (bias || ""), found;
  if (prepared.cache.hasOwnProperty(key)) {
    found = prepared.cache[key];
  } else {
    if (!prepared.rect)
      prepared.rect = prepared.view.text.getBoundingClientRect();
    if (!prepared.hasHeights) {
      ensureLineHeights(cm, prepared.view, prepared.rect);
      prepared.hasHeights = true;
    }
    found = measureCharInner(cm, prepared, ch, bias);
    if (!found.bogus) prepared.cache[key] = found;
  }
  return {left: found.left, right: found.right,
          top: varHeight ? found.rtop : found.top,
          bottom: varHeight ? found.rbottom : found.bottom};
}

var nullRect = {left: 0, right: 0, top: 0, bottom: 0};

function measureCharInner(cm, prepared, ch, bias) {
  var map = prepared.map;

  var node, start, end, collapse;
  // First, search the line map for the text node corresponding to,
  // or closest to, the target character.
  for (var i = 0; i < map.length; i += 3) {
    var mStart = map[i], mEnd = map[i + 1];
    if (ch < mStart) {
      start = 0; end = 1;
      collapse = "left";
    } else if (ch < mEnd) {
      start = ch - mStart;
      end = start + 1;
    } else if (i == map.length - 3 || ch == mEnd && map[i + 3] > ch) {
      end = mEnd - mStart;
      start = end - 1;
      if (ch >= mEnd) collapse = "right";
    }
    if (start != null) {
      node = map[i + 2];
      if (mStart == mEnd && bias == (node.insertLeft ? "left" : "right"))
        collapse = bias;
      if (bias == "left" && start == 0)
        while (i && map[i - 2] == map[i - 3] && map[i - 1].insertLeft) {
          node = map[(i -= 3) + 2];
          collapse = "left";
        }
      if (bias == "right" && start == mEnd - mStart)
        while (i < map.length - 3 && map[i + 3] == map[i + 4] && !map[i + 5].insertLeft) {
          node = map[(i += 3) + 2];
          collapse = "right";
        }
      break;
    }
  }

  var rect;
  if (node.nodeType == 3) { // If it is a text node, use a range to retrieve the coordinates.
    for (;;) {
      while (start && isExtendingChar(prepared.line.text.charAt(mStart + start))) --start;
      while (mStart + end < mEnd && isExtendingChar(prepared.line.text.charAt(mStart + end))) ++end;
      if (ie && ie_version < 9 && start == 0 && end == mEnd - mStart) {
        rect = node.parentNode.getBoundingClientRect();
      } else if (ie && cm.options.lineWrapping) {
        var rects = range(node, start, end).getClientRects();
        if (rects.length)
          rect = rects[bias == "right" ? rects.length - 1 : 0];
        else
          rect = nullRect;
      } else {
        rect = range(node, start, end).getBoundingClientRect() || nullRect;
      }
      if (rect.left || rect.right || start == 0) break;
      end = start;
      start = start - 1;
      collapse = "right";
    }
  } else { // If it is a widget, simply get the box for the whole widget.
    if (start > 0) collapse = bias = "right";
    var rects;
    if (cm.options.lineWrapping && (rects = node.getClientRects()).length > 1)
      rect = rects[bias == "right" ? rects.length - 1 : 0];
    else
      rect = node.getBoundingClientRect();
  }
  if (ie && ie_version < 9 && !start && (!rect || !rect.left && !rect.right)) {
    var rSpan = node.parentNode.getClientRects()[0];
    if (rSpan)
      rect = {left: rSpan.left, right: rSpan.left + charWidth(cm.display), top: rSpan.top, bottom: rSpan.bottom};
    else
      rect = nullRect;
  }

  if (ie && ie_version < 11) rect = maybeUpdateRectForZooming(cm.display.measure, rect);

  var rtop = rect.top - prepared.rect.top, rbot = rect.bottom - prepared.rect.top;
  var mid = (rtop + rbot) / 2;
  var heights = prepared.view.measure.heights;
  for (var i = 0; i < heights.length - 1; i++)
    if (mid < heights[i]) break;
  var top = i ? heights[i - 1] : 0, bot = heights[i];
  var result = {left: (collapse == "right" ? rect.right : rect.left) - prepared.rect.left,
                right: (collapse == "left" ? rect.left : rect.right) - prepared.rect.left,
                top: top, bottom: bot};
  if (!rect.left && !rect.right) result.bogus = true;
  if (!cm.options.singleCursorHeightPerLine) { result.rtop = rtop; result.rbottom = rbot; }

  return result;
}

// Work around problem with bounding client rects on ranges being
// returned incorrectly when zoomed on IE10 and below.
function maybeUpdateRectForZooming(measure, rect) {
  if (!window.screen || screen.logicalXDPI == null ||
      screen.logicalXDPI == screen.deviceXDPI || !hasBadZoomedRects(measure))
    return rect;
  var scaleX = screen.logicalXDPI / screen.deviceXDPI;
  var scaleY = screen.logicalYDPI / screen.deviceYDPI;
  return {left: rect.left * scaleX, right: rect.right * scaleX,
          top: rect.top * scaleY, bottom: rect.bottom * scaleY};
}

function clearLineMeasurementCacheFor(lineView) {
  if (lineView.measure) {
    lineView.measure.cache = {};
    lineView.measure.heights = null;
    if (lineView.rest) for (var i = 0; i < lineView.rest.length; i++)
      lineView.measure.caches[i] = {};
  }
}

function clearLineMeasurementCache(cm) {
  cm.display.externalMeasure = null;
  removeChildren(cm.display.lineMeasure);
  for (var i = 0; i < cm.display.view.length; i++)
    clearLineMeasurementCacheFor(cm.display.view[i]);
}

function clearCaches(cm) {
  clearLineMeasurementCache(cm);
  cm.display.cachedCharWidth = cm.display.cachedTextHeight = cm.display.cachedPaddingH = null;
  if (!cm.options.lineWrapping) cm.display.maxLineChanged = true;
  cm.display.lineNumChars = null;
}

function pageScrollX() { return window.pageXOffset || (document.documentElement || document.body).scrollLeft; }
function pageScrollY() { return window.pageYOffset || (document.documentElement || document.body).scrollTop; }

// Converts a {top, bottom, left, right} box from line-local
// coordinates into another coordinate system. Context may be one of
// "line", "div" (display.lineDiv), "local"/null (editor), or "page".
function intoCoordSystem(cm, lineObj, rect, context) {
  if (lineObj.widgets) for (var i = 0; i < lineObj.widgets.length; ++i) if (lineObj.widgets[i].above) {
    var size = widgetHeight(lineObj.widgets[i]);
    rect.top += size; rect.bottom += size;
  }
  if (context == "line") return rect;
  if (!context) context = "local";
  var yOff = heightAtLine(lineObj);
  if (context == "local") yOff += paddingTop(cm.display);
  else yOff -= cm.display.viewOffset;
  if (context == "page" || context == "window") {
    var lOff = cm.display.lineSpace.getBoundingClientRect();
    yOff += lOff.top + (context == "window" ? 0 : pageScrollY());
    var xOff = lOff.left + (context == "window" ? 0 : pageScrollX());
    rect.left += xOff; rect.right += xOff;
  }
  rect.top += yOff; rect.bottom += yOff;
  return rect;
}

// Coverts a box from "div" coords to another coordinate system.
// Context may be "window", "page", "div", or "local"/null.
function fromCoordSystem(cm, coords, context) {
  if (context == "div") return coords;
  var left = coords.left, top = coords.top;
  // First move into "page" coordinate system
  if (context == "page") {
    left -= pageScrollX();
    top -= pageScrollY();
  } else if (context == "local" || !context) {
    var localBox = cm.display.sizer.getBoundingClientRect();
    left += localBox.left;
    top += localBox.top;
  }

  var lineSpaceBox = cm.display.lineSpace.getBoundingClientRect();
  return {left: left - lineSpaceBox.left, top: top - lineSpaceBox.top};
}

function charCoords(cm, pos, context, lineObj, bias) {
  if (!lineObj) lineObj = getLine(cm.doc, pos.line);
  return intoCoordSystem(cm, lineObj, measureChar(cm, lineObj, pos.ch, bias), context);
}

// Returns a box for a given cursor position, which may have an
// 'other' property containing the position of the secondary cursor
// on a bidi boundary.
function cursorCoords(cm, pos, context, lineObj, preparedMeasure, varHeight) {
  lineObj = lineObj || getLine(cm.doc, pos.line);
  if (!preparedMeasure) preparedMeasure = prepareMeasureForLine(cm, lineObj);
  function get(ch, right) {
    var m = measureCharPrepared(cm, preparedMeasure, ch, right ? "right" : "left", varHeight);
    if (right) m.left = m.right; else m.right = m.left;
    return intoCoordSystem(cm, lineObj, m, context);
  }
  function getBidi(ch, partPos) {
    var part = order[partPos], right = part.level % 2;
    if (ch == bidiLeft(part) && partPos && part.level < order[partPos - 1].level) {
      part = order[--partPos];
      ch = bidiRight(part) - (part.level % 2 ? 0 : 1);
      right = true;
    } else if (ch == bidiRight(part) && partPos < order.length - 1 && part.level < order[partPos + 1].level) {
      part = order[++partPos];
      ch = bidiLeft(part) - part.level % 2;
      right = false;
    }
    if (right && ch == part.to && ch > part.from) return get(ch - 1);
    return get(ch, right);
  }
  var order = getOrder(lineObj), ch = pos.ch;
  if (!order) return get(ch);
  var partPos = getBidiPartAt(order, ch);
  var val = getBidi(ch, partPos);
  if (bidiOther != null) val.other = getBidi(ch, bidiOther);
  return val;
}

// Used to cheaply estimate the coordinates for a position. Used for
// intermediate scroll updates.
function estimateCoords(cm, pos) {
  var left = 0, pos = clipPos(cm.doc, pos);
  if (!cm.options.lineWrapping) left = charWidth(cm.display) * pos.ch;
  var lineObj = getLine(cm.doc, pos.line);
  var top = heightAtLine(lineObj) + paddingTop(cm.display);
  return {left: left, right: left, top: top, bottom: top + lineObj.height};
}

// Positions returned by coordsChar contain some extra information.
// xRel is the relative x position of the input coordinates compared
// to the found position (so xRel > 0 means the coordinates are to
// the right of the character position, for example). When outside
// is true, that means the coordinates lie outside the line's
// vertical range.
function PosWithInfo(line, ch, outside, xRel) {
  var pos = Pos(line, ch);
  pos.xRel = xRel;
  if (outside) pos.outside = true;
  return pos;
}

// Compute the character position closest to the given coordinates.
// Input must be lineSpace-local ("div" coordinate system).
function coordsChar(cm, x, y) {
  var doc = cm.doc;
  y += cm.display.viewOffset;
  if (y < 0) return PosWithInfo(doc.first, 0, true, -1);
  var lineN = lineAtHeight(doc, y), last = doc.first + doc.size - 1;
  if (lineN > last)
    return PosWithInfo(doc.first + doc.size - 1, getLine(doc, last).text.length, true, 1);
  if (x < 0) x = 0;

  var lineObj = getLine(doc, lineN);
  for (;;) {
    var found = coordsCharInner(cm, lineObj, lineN, x, y);
    var merged = collapsedSpanAtEnd(lineObj);
    var mergedPos = merged && merged.find(0, true);
    if (merged && (found.ch > mergedPos.from.ch || found.ch == mergedPos.from.ch && found.xRel > 0))
      lineN = lineNo(lineObj = mergedPos.to.line);
    else
      return found;
  }
}

function coordsCharInner(cm, lineObj, lineNo, x, y) {
  var innerOff = y - heightAtLine(lineObj);
  var wrongLine = false, adjust = 2 * cm.display.wrapper.clientWidth;
  var preparedMeasure = prepareMeasureForLine(cm, lineObj);

  function getX(ch) {
    var sp = cursorCoords(cm, Pos(lineNo, ch), "line", lineObj, preparedMeasure);
    wrongLine = true;
    if (innerOff > sp.bottom) return sp.left - adjust;
    else if (innerOff < sp.top) return sp.left + adjust;
    else wrongLine = false;
    return sp.left;
  }

  var bidi = getOrder(lineObj), dist = lineObj.text.length;
  var from = lineLeft(lineObj), to = lineRight(lineObj);
  var fromX = getX(from), fromOutside = wrongLine, toX = getX(to), toOutside = wrongLine;

  if (x > toX) return PosWithInfo(lineNo, to, toOutside, 1);
  // Do a binary search between these bounds.
  for (;;) {
    if (bidi ? to == from || to == moveVisually(lineObj, from, 1) : to - from <= 1) {
      var ch = x < fromX || x - fromX <= toX - x ? from : to;
      var xDiff = x - (ch == from ? fromX : toX);
      while (isExtendingChar(lineObj.text.charAt(ch))) ++ch;
      var pos = PosWithInfo(lineNo, ch, ch == from ? fromOutside : toOutside,
                            xDiff < -1 ? -1 : xDiff > 1 ? 1 : 0);
      return pos;
    }
    var step = Math.ceil(dist / 2), middle = from + step;
    if (bidi) {
      middle = from;
      for (var i = 0; i < step; ++i) middle = moveVisually(lineObj, middle, 1);
    }
    var middleX = getX(middle);
    if (middleX > x) {to = middle; toX = middleX; if (toOutside = wrongLine) toX += 1000; dist = step;}
    else {from = middle; fromX = middleX; fromOutside = wrongLine; dist -= step;}
  }
}

var measureText;
// Compute the default text height.
function textHeight(display) {
  if (display.cachedTextHeight != null) return display.cachedTextHeight;
  if (measureText == null) {
    measureText = elt("pre");
    // Measure a bunch of lines, for browsers that compute
    // fractional heights.
    for (var i = 0; i < 49; ++i) {
      measureText.appendChild(document.createTextNode("x"));
      measureText.appendChild(elt("br"));
    }
    measureText.appendChild(document.createTextNode("x"));
  }
  removeChildrenAndAdd(display.measure, measureText);
  var height = measureText.offsetHeight / 50;
  if (height > 3) display.cachedTextHeight = height;
  removeChildren(display.measure);
  return height || 1;
}

// Compute the default character width.
function charWidth(display) {
  if (display.cachedCharWidth != null) return display.cachedCharWidth;
  var anchor = elt("span", "xxxxxxxxxx");
  var pre = elt("pre", [anchor]);
  removeChildrenAndAdd(display.measure, pre);
  var rect = anchor.getBoundingClientRect(), width = (rect.right - rect.left) / 10;
  if (width > 2) display.cachedCharWidth = width;
  return width || 10;
}

// OPERATIONS

// Operations are used to wrap a series of changes to the editor
// state in such a way that each change won't have to update the
// cursor and display (which would be awkward, slow, and
// error-prone). Instead, display updates are batched and then all
// combined and executed at once.

var operationGroup = null;

var nextOpId = 0;
// Start a new operation.
function startOperation(cm) {
  cm.curOp = {
    cm: cm,
    viewChanged: false,      // Flag that indicates that lines might need to be redrawn
    startHeight: cm.doc.height, // Used to detect need to update scrollbar
    forceUpdate: false,      // Used to force a redraw
    updateInput: null,       // Whether to reset the input textarea
    typing: false,           // Whether this reset should be careful to leave existing text (for compositing)
    changeObjs: null,        // Accumulated changes, for firing change events
    cursorActivityHandlers: null, // Set of handlers to fire cursorActivity on
    cursorActivityCalled: 0, // Tracks which cursorActivity handlers have been called already
    selectionChanged: false, // Whether the selection needs to be redrawn
    updateMaxLine: false,    // Set when the widest line needs to be determined anew
    scrollLeft: null, scrollTop: null, // Intermediate scroll position, not pushed to DOM yet
    scrollToPos: null,       // Used to scroll to a specific position
    id: ++nextOpId           // Unique ID
  };
  if (operationGroup) {
    operationGroup.ops.push(cm.curOp);
  } else {
    cm.curOp.ownsGroup = operationGroup = {
      ops: [cm.curOp],
      delayedCallbacks: []
    };
  }
}

function fireCallbacksForOps(group) {
  // Calls delayed callbacks and cursorActivity handlers until no
  // new ones appear
  var callbacks = group.delayedCallbacks, i = 0;
  do {
    for (; i < callbacks.length; i++)
      callbacks[i]();
    for (var j = 0; j < group.ops.length; j++) {
      var op = group.ops[j];
      if (op.cursorActivityHandlers)
        while (op.cursorActivityCalled < op.cursorActivityHandlers.length)
          op.cursorActivityHandlers[op.cursorActivityCalled++](op.cm);
    }
  } while (i < callbacks.length);
}

// Finish an operation, updating the display and signalling delayed events
function endOperation(cm) {
  var op = cm.curOp, group = op.ownsGroup;
  if (!group) return;

  try { fireCallbacksForOps(group); }
  finally {
    operationGroup = null;
    for (var i = 0; i < group.ops.length; i++)
      group.ops[i].cm.curOp = null;
    endOperations(group);
  }
}

// The DOM updates done when an operation finishes are batched so
// that the minimum number of relayouts are required.
function endOperations(group) {
  var ops = group.ops;
  for (var i = 0; i < ops.length; i++) // Read DOM
    endOperation_R1(ops[i]);
  for (var i = 0; i < ops.length; i++) // Write DOM (maybe)
    endOperation_W1(ops[i]);
  for (var i = 0; i < ops.length; i++) // Read DOM
    endOperation_R2(ops[i]);
  for (var i = 0; i < ops.length; i++) // Write DOM (maybe)
    endOperation_W2(ops[i]);
  for (var i = 0; i < ops.length; i++) // Read DOM
    endOperation_finish(ops[i]);
}

function endOperation_R1(op) {
  var cm = op.cm, display = cm.display;
  if (op.updateMaxLine) findMaxLine(cm);

  op.mustUpdate = op.viewChanged || op.forceUpdate || op.scrollTop != null ||
    op.scrollToPos && (op.scrollToPos.from.line < display.viewFrom ||
                       op.scrollToPos.to.line >= display.viewTo) ||
    display.maxLineChanged && cm.options.lineWrapping;
  op.update = op.mustUpdate &&
    new DisplayUpdate(cm, op.mustUpdate && {top: op.scrollTop, ensure: op.scrollToPos}, op.forceUpdate);
}

function endOperation_W1(op) {
  op.updatedDisplay = op.mustUpdate && updateDisplayIfNeeded(op.cm, op.update);
}

function endOperation_R2(op) {
  var cm = op.cm, display = cm.display;
  if (op.updatedDisplay) updateHeightsInViewport(cm);

  op.barMeasure = measureForScrollbars(cm);

  // If the max line changed since it was last measured, measure it,
  // and ensure the document's width matches it.
  // updateDisplay_W2 will use these properties to do the actual resizing
  if (display.maxLineChanged && !cm.options.lineWrapping) {
    op.adjustWidthTo = measureChar(cm, display.maxLine, display.maxLine.text.length).left + 3;
    op.maxScrollLeft = Math.max(0, display.sizer.offsetLeft + op.adjustWidthTo +
                                scrollerCutOff - display.scroller.clientWidth);
  }

  if (op.updatedDisplay || op.selectionChanged)
    op.newSelectionNodes = drawSelection(cm);
}

function endOperation_W2(op) {
  var cm = op.cm;

  if (op.adjustWidthTo != null) {
    cm.display.sizer.style.minWidth = op.adjustWidthTo + "px";
    if (op.maxScrollLeft < cm.doc.scrollLeft)
      setScrollLeft(cm, Math.min(cm.display.scroller.scrollLeft, op.maxScrollLeft), true);
    cm.display.maxLineChanged = false;
  }

  if (op.newSelectionNodes)
    showSelection(cm, op.newSelectionNodes);
  if (op.updatedDisplay)
    setDocumentHeight(cm, op.barMeasure);
  if (op.updatedDisplay || op.startHeight != cm.doc.height)
    updateScrollbars(cm, op.barMeasure);

  if (op.selectionChanged) restartBlink(cm);

  if (cm.state.focused && op.updateInput)
    resetInput(cm, op.typing);
}

function endOperation_finish(op) {
  var cm = op.cm, display = cm.display, doc = cm.doc;

  if (op.adjustWidthTo != null && Math.abs(op.barMeasure.scrollWidth - cm.display.scroller.scrollWidth) > 1)
    updateScrollbars(cm);

  if (op.updatedDisplay) postUpdateDisplay(cm, op.update);

  // Abort mouse wheel delta measurement, when scrolling explicitly
  if (display.wheelStartX != null && (op.scrollTop != null || op.scrollLeft != null || op.scrollToPos))
    display.wheelStartX = display.wheelStartY = null;

  // Propagate the scroll position to the actual DOM scroller
  if (op.scrollTop != null && display.scroller.scrollTop != op.scrollTop) {
    var top = Math.max(0, Math.min(display.scroller.scrollHeight - display.scroller.clientHeight, op.scrollTop));
    display.scroller.scrollTop = display.scrollbarV.scrollTop = doc.scrollTop = top;
  }
  if (op.scrollLeft != null && display.scroller.scrollLeft != op.scrollLeft) {
    var left = Math.max(0, Math.min(display.scroller.scrollWidth - display.scroller.clientWidth, op.scrollLeft));
    display.scroller.scrollLeft = display.scrollbarH.scrollLeft = doc.scrollLeft = left;
    alignHorizontally(cm);
  }
  // If we need to scroll a specific position into view, do so.
  if (op.scrollToPos) {
    var coords = scrollPosIntoView(cm, clipPos(doc, op.scrollToPos.from),
                                   clipPos(doc, op.scrollToPos.to), op.scrollToPos.margin);
    if (op.scrollToPos.isCursor && cm.state.focused) maybeScrollWindow(cm, coords);
  }

  // Fire events for markers that are hidden/unidden by editing or
  // undoing
  var hidden = op.maybeHiddenMarkers, unhidden = op.maybeUnhiddenMarkers;
  if (hidden) for (var i = 0; i < hidden.length; ++i)
    if (!hidden[i].lines.length) signal(hidden[i], "hide");
  if (unhidden) for (var i = 0; i < unhidden.length; ++i)
    if (unhidden[i].lines.length) signal(unhidden[i], "unhide");

  if (display.wrapper.offsetHeight)
    doc.scrollTop = cm.display.scroller.scrollTop;

  // Apply workaround for two webkit bugs
  if (op.updatedDisplay && webkit) {
    if (cm.options.lineWrapping)
      checkForWebkitWidthBug(cm, op.barMeasure); // (Issue #2420)
    if (op.barMeasure.scrollWidth > op.barMeasure.clientWidth &&
        op.barMeasure.scrollWidth < op.barMeasure.clientWidth + 1 &&
        !hScrollbarTakesSpace(cm))
      updateScrollbars(cm); // (Issue #2562)
  }

  // Fire change events, and delayed event handlers
  if (op.changeObjs)
    signal(cm, "changes", cm, op.changeObjs);
}

// Run the given function in an operation
function runInOp(cm, f) {
  if (cm.curOp) return f();
  startOperation(cm);
  try { return f(); }
  finally { endOperation(cm); }
}
// Wraps a function in an operation. Returns the wrapped function.
function operation(cm, f) {
  return function() {
    if (cm.curOp) return f.apply(cm, arguments);
    startOperation(cm);
    try { return f.apply(cm, arguments); }
    finally { endOperation(cm); }
  };
}
// Used to add methods to editor and doc instances, wrapping them in
// operations.
function methodOp(f) {
  return function() {
    if (this.curOp) return f.apply(this, arguments);
    startOperation(this);
    try { return f.apply(this, arguments); }
    finally { endOperation(this); }
  };
}
function docMethodOp(f) {
  return function() {
    var cm = this.cm;
    if (!cm || cm.curOp) return f.apply(this, arguments);
    startOperation(cm);
    try { return f.apply(this, arguments); }
    finally { endOperation(cm); }
  };
}

// VIEW TRACKING

// These objects are used to represent the visible (currently drawn)
// part of the document. A LineView may correspond to multiple
// logical lines, if those are connected by collapsed ranges.
function LineView(doc, line, lineN) {
  // The starting line
  this.line = line;
  // Continuing lines, if any
  this.rest = visualLineContinued(line);
  // Number of logical lines in this visual line
  this.size = this.rest ? lineNo(lst(this.rest)) - lineN + 1 : 1;
  this.node = this.text = null;
  this.hidden = lineIsHidden(doc, line);
}

// Create a range of LineView objects for the given lines.
function buildViewArray(cm, from, to) {
  var array = [], nextPos;
  for (var pos = from; pos < to; pos = nextPos) {
    var view = new LineView(cm.doc, getLine(cm.doc, pos), pos);
    nextPos = pos + view.size;
    array.push(view);
  }
  return array;
}

// Updates the display.view data structure for a given change to the
// document. From and to are in pre-change coordinates. Lendiff is
// the amount of lines added or subtracted by the change. This is
// used for changes that span multiple lines, or change the way
// lines are divided into visual lines. regLineChange (below)
// registers single-line changes.
function regChange(cm, from, to, lendiff) {
  if (from == null) from = cm.doc.first;
  if (to == null) to = cm.doc.first + cm.doc.size;
  if (!lendiff) lendiff = 0;

  var display = cm.display;
  if (lendiff && to < display.viewTo &&
      (display.updateLineNumbers == null || display.updateLineNumbers > from))
    display.updateLineNumbers = from;

  cm.curOp.viewChanged = true;

  if (from >= display.viewTo) { // Change after
    if (sawCollapsedSpans && visualLineNo(cm.doc, from) < display.viewTo)
      resetView(cm);
  } else if (to <= display.viewFrom) { // Change before
    if (sawCollapsedSpans && visualLineEndNo(cm.doc, to + lendiff) > display.viewFrom) {
      resetView(cm);
    } else {
      display.viewFrom += lendiff;
      display.viewTo += lendiff;
    }
  } else if (from <= display.viewFrom && to >= display.viewTo) { // Full overlap
    resetView(cm);
  } else if (from <= display.viewFrom) { // Top overlap
    var cut = viewCuttingPoint(cm, to, to + lendiff, 1);
    if (cut) {
      display.view = display.view.slice(cut.index);
      display.viewFrom = cut.lineN;
      display.viewTo += lendiff;
    } else {
      resetView(cm);
    }
  } else if (to >= display.viewTo) { // Bottom overlap
    var cut = viewCuttingPoint(cm, from, from, -1);
    if (cut) {
      display.view = display.view.slice(0, cut.index);
      display.viewTo = cut.lineN;
    } else {
      resetView(cm);
    }
  } else { // Gap in the middle
    var cutTop = viewCuttingPoint(cm, from, from, -1);
    var cutBot = viewCuttingPoint(cm, to, to + lendiff, 1);
    if (cutTop && cutBot) {
      display.view = display.view.slice(0, cutTop.index)
        .concat(buildViewArray(cm, cutTop.lineN, cutBot.lineN))
        .concat(display.view.slice(cutBot.index));
      display.viewTo += lendiff;
    } else {
      resetView(cm);
    }
  }

  var ext = display.externalMeasured;
  if (ext) {
    if (to < ext.lineN)
      ext.lineN += lendiff;
    else if (from < ext.lineN + ext.size)
      display.externalMeasured = null;
  }
}

// Register a change to a single line. Type must be one of "text",
// "gutter", "class", "widget"
function regLineChange(cm, line, type) {
  cm.curOp.viewChanged = true;
  var display = cm.display, ext = cm.display.externalMeasured;
  if (ext && line >= ext.lineN && line < ext.lineN + ext.size)
    display.externalMeasured = null;

  if (line < display.viewFrom || line >= display.viewTo) return;
  var lineView = display.view[findViewIndex(cm, line)];
  if (lineView.node == null) return;
  var arr = lineView.changes || (lineView.changes = []);
  if (indexOf(arr, type) == -1) arr.push(type);
}

// Clear the view.
function resetView(cm) {
  cm.display.viewFrom = cm.display.viewTo = cm.doc.first;
  cm.display.view = [];
  cm.display.viewOffset = 0;
}

// Find the view element corresponding to a given line. Return null
// when the line isn't visible.
function findViewIndex(cm, n) {
  if (n >= cm.display.viewTo) return null;
  n -= cm.display.viewFrom;
  if (n < 0) return null;
  var view = cm.display.view;
  for (var i = 0; i < view.length; i++) {
    n -= view[i].size;
    if (n < 0) return i;
  }
}

function viewCuttingPoint(cm, oldN, newN, dir) {
  var index = findViewIndex(cm, oldN), diff, view = cm.display.view;
  if (!sawCollapsedSpans || newN == cm.doc.first + cm.doc.size)
    return {index: index, lineN: newN};
  for (var i = 0, n = cm.display.viewFrom; i < index; i++)
    n += view[i].size;
  if (n != oldN) {
    if (dir > 0) {
      if (index == view.length - 1) return null;
      diff = (n + view[index].size) - oldN;
      index++;
    } else {
      diff = n - oldN;
    }
    oldN += diff; newN += diff;
  }
  while (visualLineNo(cm.doc, newN) != newN) {
    if (index == (dir < 0 ? 0 : view.length - 1)) return null;
    newN += dir * view[index - (dir < 0 ? 1 : 0)].size;
    index += dir;
  }
  return {index: index, lineN: newN};
}

// Force the view to cover a given range, adding empty view element
// or clipping off existing ones as needed.
function adjustView(cm, from, to) {
  var display = cm.display, view = display.view;
  if (view.length == 0 || from >= display.viewTo || to <= display.viewFrom) {
    display.view = buildViewArray(cm, from, to);
    display.viewFrom = from;
  } else {
    if (display.viewFrom > from)
      display.view = buildViewArray(cm, from, display.viewFrom).concat(display.view);
    else if (display.viewFrom < from)
      display.view = display.view.slice(findViewIndex(cm, from));
    display.viewFrom = from;
    if (display.viewTo < to)
      display.view = display.view.concat(buildViewArray(cm, display.viewTo, to));
    else if (display.viewTo > to)
      display.view = display.view.slice(0, findViewIndex(cm, to));
  }
  display.viewTo = to;
}

// Count the number of lines in the view whose DOM representation is
// out of date (or nonexistent).
function countDirtyView(cm) {
  var view = cm.display.view, dirty = 0;
  for (var i = 0; i < view.length; i++) {
    var lineView = view[i];
    if (!lineView.hidden && (!lineView.node || lineView.changes)) ++dirty;
  }
  return dirty;
}

// INPUT HANDLING

// Poll for input changes, using the normal rate of polling. This
// runs as long as the editor is focused.
function slowPoll(cm) {
  if (cm.display.pollingFast) return;
  cm.display.poll.set(cm.options.pollInterval, function() {
    readInput(cm);
    if (cm.state.focused) slowPoll(cm);
  });
}

// When an event has just come in that is likely to add or change
// something in the input textarea, we poll faster, to ensure that
// the change appears on the screen quickly.
function fastPoll(cm) {
  var missed = false;
  cm.display.pollingFast = true;
  function p() {
    var changed = readInput(cm);
    if (!changed && !missed) {missed = true; cm.display.poll.set(60, p);}
    else {cm.display.pollingFast = false; slowPoll(cm);}
  }
  cm.display.poll.set(20, p);
}

// This will be set to an array of strings when copying, so that,
// when pasting, we know what kind of selections the copied text
// was made out of.
var lastCopied = null;

// Read input from the textarea, and update the document to match.
// When something is selected, it is present in the textarea, and
// selected (unless it is huge, in which case a placeholder is
// used). When nothing is selected, the cursor sits after previously
// seen text (can be empty), which is stored in prevInput (we must
// not reset the textarea when typing, because that breaks IME).
function readInput(cm) {
  var input = cm.display.input, prevInput = cm.display.prevInput, doc = cm.doc;
  // Since this is called a *lot*, try to bail out as cheaply as
  // possible when it is clear that nothing happened. hasSelection
  // will be the case when there is a lot of text in the textarea,
  // in which case reading its value would be expensive.
  if (!cm.state.focused || (hasSelection(input) && !prevInput) || isReadOnly(cm) || cm.options.disableInput)
    return false;
  // See paste handler for more on the fakedLastChar kludge
  if (cm.state.pasteIncoming && cm.state.fakedLastChar) {
    input.value = input.value.substring(0, input.value.length - 1);
    cm.state.fakedLastChar = false;
  }
  var text = input.value;
  // If nothing changed, bail.
  if (text == prevInput && !cm.somethingSelected()) return false;
  // Work around nonsensical selection resetting in IE9/10, and
  // inexplicable appearance of private area unicode characters on
  // some key combos in Mac (#2689).
  if (ie && ie_version >= 9 && cm.display.inputHasSelection === text ||
      mac && /[\uf700-\uf7ff]/.test(text)) {
    resetInput(cm);
    return false;
  }

  var withOp = !cm.curOp;
  if (withOp) startOperation(cm);
  cm.display.shift = false;

  if (text.charCodeAt(0) == 0x200b && doc.sel == cm.display.selForContextMenu && !prevInput)
    prevInput = "\u200b";
  // Find the part of the input that is actually new
  var same = 0, l = Math.min(prevInput.length, text.length);
  while (same < l && prevInput.charCodeAt(same) == text.charCodeAt(same)) ++same;
  var inserted = text.slice(same), textLines = splitLines(inserted);

  // When pasing N lines into N selections, insert one line per selection
  var multiPaste = null;
  if (cm.state.pasteIncoming && doc.sel.ranges.length > 1) {
    if (lastCopied && lastCopied.join("\n") == inserted)
      multiPaste = doc.sel.ranges.length % lastCopied.length == 0 && map(lastCopied, splitLines);
    else if (textLines.length == doc.sel.ranges.length)
      multiPaste = map(textLines, function(l) { return [l]; });
  }

  // Normal behavior is to insert the new text into every selection
  for (var i = doc.sel.ranges.length - 1; i >= 0; i--) {
    var range = doc.sel.ranges[i];
    var from = range.from(), to = range.to();
    // Handle deletion
    if (same < prevInput.length)
      from = Pos(from.line, from.ch - (prevInput.length - same));
    // Handle overwrite
    else if (cm.state.overwrite && range.empty() && !cm.state.pasteIncoming)
      to = Pos(to.line, Math.min(getLine(doc, to.line).text.length, to.ch + lst(textLines).length));
    var updateInput = cm.curOp.updateInput;
    var changeEvent = {from: from, to: to, text: multiPaste ? multiPaste[i % multiPaste.length] : textLines,
                       origin: cm.state.pasteIncoming ? "paste" : cm.state.cutIncoming ? "cut" : "+input"};
    makeChange(cm.doc, changeEvent);
    signalLater(cm, "inputRead", cm, changeEvent);
    // When an 'electric' character is inserted, immediately trigger a reindent
    if (inserted && !cm.state.pasteIncoming && cm.options.electricChars &&
        cm.options.smartIndent && range.head.ch < 100 &&
        (!i || doc.sel.ranges[i - 1].head.line != range.head.line)) {
      var mode = cm.getModeAt(range.head);
      if (mode.electricChars) {
        for (var j = 0; j < mode.electricChars.length; j++)
          if (inserted.indexOf(mode.electricChars.charAt(j)) > -1) {
            indentLine(cm, range.head.line, "smart");
            break;
          }
      } else if (mode.electricInput) {
        var end = changeEnd(changeEvent);
        if (mode.electricInput.test(getLine(doc, end.line).text.slice(0, end.ch)))
          indentLine(cm, range.head.line, "smart");
      }
    }
  }
  ensureCursorVisible(cm);
  cm.curOp.updateInput = updateInput;
  cm.curOp.typing = true;

  // Don't leave long text in the textarea, since it makes further polling slow
  if (text.length > 1000 || text.indexOf("\n") > -1) input.value = cm.display.prevInput = "";
  else cm.display.prevInput = text;
  if (withOp) endOperation(cm);
  cm.state.pasteIncoming = cm.state.cutIncoming = false;
  return true;
}

// Reset the input to correspond to the selection (or to be empty,
// when not typing and nothing is selected)
function resetInput(cm, typing) {
  var minimal, selected, doc = cm.doc;
  if (cm.somethingSelected()) {
    cm.display.prevInput = "";
    var range = doc.sel.primary();
    minimal = hasCopyEvent &&
      (range.to().line - range.from().line > 100 || (selected = cm.getSelection()).length > 1000);
    var content = minimal ? "-" : selected || cm.getSelection();
    cm.display.input.value = content;
    if (cm.state.focused) selectInput(cm.display.input);
    if (ie && ie_version >= 9) cm.display.inputHasSelection = content;
  } else if (!typing) {
    cm.display.prevInput = cm.display.input.value = "";
    if (ie && ie_version >= 9) cm.display.inputHasSelection = null;
  }
  cm.display.inaccurateSelection = minimal;
}

function focusInput(cm) {
  if (cm.options.readOnly != "nocursor" && (!mobile || activeElt() != cm.display.input))
    cm.display.input.focus();
}

function ensureFocus(cm) {
  if (!cm.state.focused) { focusInput(cm); onFocus(cm); }
}

function isReadOnly(cm) {
  return cm.options.readOnly || cm.doc.cantEdit;
}

// EVENT HANDLERS

// Attach the necessary event handlers when initializing the editor
function registerEventHandlers(cm) {
  var d = cm.display;
  on(d.scroller, "mousedown", operation(cm, onMouseDown));
  // Older IE's will not fire a second mousedown for a double click
  if (ie && ie_version < 11)
    on(d.scroller, "dblclick", operation(cm, function(e) {
      if (signalDOMEvent(cm, e)) return;
      var pos = posFromMouse(cm, e);
      if (!pos || clickInGutter(cm, e) || eventInWidget(cm.display, e)) return;
      e_preventDefault(e);
      var word = findWordAt(cm, pos);
      extendSelection(cm.doc, word.anchor, word.head);
    }));
  else
    on(d.scroller, "dblclick", function(e) { signalDOMEvent(cm, e) || e_preventDefault(e); });
  // Prevent normal selection in the editor (we handle our own)
  on(d.lineSpace, "selectstart", function(e) {
    if (!eventInWidget(d, e)) e_preventDefault(e);
  });
  // Some browsers fire contextmenu *after* opening the menu, at
  // which point we can't mess with it anymore. Context menu is
  // handled in onMouseDown for these browsers.
  if (!captureRightClick) on(d.scroller, "contextmenu", function(e) {onContextMenu(cm, e);});

  // Sync scrolling between fake scrollbars and real scrollable
  // area, ensure viewport is updated when scrolling.
  on(d.scroller, "scroll", function() {
    if (d.scroller.clientHeight) {
      setScrollTop(cm, d.scroller.scrollTop);
      setScrollLeft(cm, d.scroller.scrollLeft, true);
      signal(cm, "scroll", cm);
    }
  });
  on(d.scrollbarV, "scroll", function() {
    if (d.scroller.clientHeight) setScrollTop(cm, d.scrollbarV.scrollTop);
  });
  on(d.scrollbarH, "scroll", function() {
    if (d.scroller.clientHeight) setScrollLeft(cm, d.scrollbarH.scrollLeft);
  });

  // Listen to wheel events in order to try and update the viewport on time.
  on(d.scroller, "mousewheel", function(e){onScrollWheel(cm, e);});
  on(d.scroller, "DOMMouseScroll", function(e){onScrollWheel(cm, e);});

  // Prevent clicks in the scrollbars from killing focus
  function reFocus() { if (cm.state.focused) setTimeout(bind(focusInput, cm), 0); }
  on(d.scrollbarH, "mousedown", reFocus);
  on(d.scrollbarV, "mousedown", reFocus);
  // Prevent wrapper from ever scrolling
  on(d.wrapper, "scroll", function() { d.wrapper.scrollTop = d.wrapper.scrollLeft = 0; });

  on(d.input, "keyup", function(e) { onKeyUp.call(cm, e); });
  on(d.input, "input", function() {
    if (ie && ie_version >= 9 && cm.display.inputHasSelection) cm.display.inputHasSelection = null;
    fastPoll(cm);
  });
  on(d.input, "keydown", operation(cm, onKeyDown));
  on(d.input, "keypress", operation(cm, onKeyPress));
  on(d.input, "focus", bind(onFocus, cm));
  on(d.input, "blur", bind(onBlur, cm));

  function drag_(e) {
    if (!signalDOMEvent(cm, e)) e_stop(e);
  }
  if (cm.options.dragDrop) {
    on(d.scroller, "dragstart", function(e){onDragStart(cm, e);});
    on(d.scroller, "dragenter", drag_);
    on(d.scroller, "dragover", drag_);
    on(d.scroller, "drop", operation(cm, onDrop));
  }
  on(d.scroller, "paste", function(e) {
    if (eventInWidget(d, e)) return;
    cm.state.pasteIncoming = true;
    focusInput(cm);
    fastPoll(cm);
  });
  on(d.input, "paste", function() {
    // Workaround for webkit bug https://bugs.webkit.org/show_bug.cgi?id=90206
    // Add a char to the end of textarea before paste occur so that
    // selection doesn't span to the end of textarea.
    if (webkit && !cm.state.fakedLastChar && !(new Date - cm.state.lastMiddleDown < 200)) {
      var start = d.input.selectionStart, end = d.input.selectionEnd;
      d.input.value += "$";
      // The selection end needs to be set before the start, otherwise there
      // can be an intermediate non-empty selection between the two, which
      // can override the middle-click paste buffer on linux and cause the
      // wrong thing to get pasted.
      d.input.selectionEnd = end;
      d.input.selectionStart = start;
      cm.state.fakedLastChar = true;
    }
    cm.state.pasteIncoming = true;
    fastPoll(cm);
  });

  function prepareCopyCut(e) {
    if (cm.somethingSelected()) {
      lastCopied = cm.getSelections();
      if (d.inaccurateSelection) {
        d.prevInput = "";
        d.inaccurateSelection = false;
        d.input.value = lastCopied.join("\n");
        selectInput(d.input);
      }
    } else {
      var text = [], ranges = [];
      for (var i = 0; i < cm.doc.sel.ranges.length; i++) {
        var line = cm.doc.sel.ranges[i].head.line;
        var lineRange = {anchor: Pos(line, 0), head: Pos(line + 1, 0)};
        ranges.push(lineRange);
        text.push(cm.getRange(lineRange.anchor, lineRange.head));
      }
      if (e.type == "cut") {
        cm.setSelections(ranges, null, sel_dontScroll);
      } else {
        d.prevInput = "";
        d.input.value = text.join("\n");
        selectInput(d.input);
      }
      lastCopied = text;
    }
    if (e.type == "cut") cm.state.cutIncoming = true;
  }
  on(d.input, "cut", prepareCopyCut);
  on(d.input, "copy", prepareCopyCut);

  // Needed to handle Tab key in KHTML
  if (khtml) on(d.sizer, "mouseup", function() {
    if (activeElt() == d.input) d.input.blur();
    focusInput(cm);
  });
}

// Called when the window resizes
function onResize(cm) {
  // Might be a text scaling operation, clear size caches.
  var d = cm.display;
  d.cachedCharWidth = d.cachedTextHeight = d.cachedPaddingH = null;
  cm.setSize();
}

// MOUSE EVENTS

// Return true when the given mouse event happened in a widget
function eventInWidget(display, e) {
  for (var n = e_target(e); n != display.wrapper; n = n.parentNode) {
    if (!n || n.ignoreEvents || n.parentNode == display.sizer && n != display.mover) return true;
  }
}

// Given a mouse event, find the corresponding position. If liberal
// is false, it checks whether a gutter or scrollbar was clicked,
// and returns null if it was. forRect is used by rectangular
// selections, and tries to estimate a character position even for
// coordinates beyond the right of the text.
function posFromMouse(cm, e, liberal, forRect) {
  var display = cm.display;
  if (!liberal) {
    var target = e_target(e);
    if (target == display.scrollbarH || target == display.scrollbarV ||
        target == display.scrollbarFiller || target == display.gutterFiller) return null;
  }
  var x, y, space = display.lineSpace.getBoundingClientRect();
  // Fails unpredictably on IE[67] when mouse is dragged around quickly.
  try { x = e.clientX - space.left; y = e.clientY - space.top; }
  catch (e) { return null; }
  var coords = coordsChar(cm, x, y), line;
  if (forRect && coords.xRel == 1 && (line = getLine(cm.doc, coords.line).text).length == coords.ch) {
    var colDiff = countColumn(line, line.length, cm.options.tabSize) - line.length;
    coords = Pos(coords.line, Math.max(0, Math.round((x - paddingH(cm.display).left) / charWidth(cm.display)) - colDiff));
  }
  return coords;
}

// A mouse down can be a single click, double click, triple click,
// start of selection drag, start of text drag, new cursor
// (ctrl-click), rectangle drag (alt-drag), or xwin
// middle-click-paste. Or it might be a click on something we should
// not interfere with, such as a scrollbar or widget.
function onMouseDown(e) {
  if (signalDOMEvent(this, e)) return;
  var cm = this, display = cm.display;
  display.shift = e.shiftKey;

  if (eventInWidget(display, e)) {
    if (!webkit) {
      // Briefly turn off draggability, to allow widgets to do
      // normal dragging things.
      display.scroller.draggable = false;
      setTimeout(function(){display.scroller.draggable = true;}, 100);
    }
    return;
  }
  if (clickInGutter(cm, e)) return;
  var start = posFromMouse(cm, e);
  window.focus();

  switch (e_button(e)) {
  case 1:
    if (start)
      leftButtonDown(cm, e, start);
    else if (e_target(e) == display.scroller)
      e_preventDefault(e);
    break;
  case 2:
    if (webkit) cm.state.lastMiddleDown = +new Date;
    if (start) extendSelection(cm.doc, start);
    setTimeout(bind(focusInput, cm), 20);
    e_preventDefault(e);
    break;
  case 3:
    if (captureRightClick) onContextMenu(cm, e);
    break;
  }
}

var lastClick, lastDoubleClick;
function leftButtonDown(cm, e, start) {
  setTimeout(bind(ensureFocus, cm), 0);

  var now = +new Date, type;
  if (lastDoubleClick && lastDoubleClick.time > now - 400 && cmp(lastDoubleClick.pos, start) == 0) {
    type = "triple";
  } else if (lastClick && lastClick.time > now - 400 && cmp(lastClick.pos, start) == 0) {
    type = "double";
    lastDoubleClick = {time: now, pos: start};
  } else {
    type = "single";
    lastClick = {time: now, pos: start};
  }

  var sel = cm.doc.sel, modifier = mac ? e.metaKey : e.ctrlKey;
  if (cm.options.dragDrop && dragAndDrop && !isReadOnly(cm) &&
      type == "single" && sel.contains(start) > -1 && sel.somethingSelected())
    leftButtonStartDrag(cm, e, start, modifier);
  else
    leftButtonSelect(cm, e, start, type, modifier);
}

// Start a text drag. When it ends, see if any dragging actually
// happen, and treat as a click if it didn't.
function leftButtonStartDrag(cm, e, start, modifier) {
  var display = cm.display;
  var dragEnd = operation(cm, function(e2) {
    if (webkit) display.scroller.draggable = false;
    cm.state.draggingText = false;
    off(document, "mouseup", dragEnd);
    off(display.scroller, "drop", dragEnd);
    if (Math.abs(e.clientX - e2.clientX) + Math.abs(e.clientY - e2.clientY) < 10) {
      e_preventDefault(e2);
      if (!modifier)
        extendSelection(cm.doc, start);
      focusInput(cm);
      // Work around unexplainable focus problem in IE9 (#2127)
      if (ie && ie_version == 9)
        setTimeout(function() {document.body.focus(); focusInput(cm);}, 20);
    }
  });
  // Let the drag handler handle this.
  if (webkit) display.scroller.draggable = true;
  cm.state.draggingText = dragEnd;
  // IE's approach to draggable
  if (display.scroller.dragDrop) display.scroller.dragDrop();
  on(document, "mouseup", dragEnd);
  on(display.scroller, "drop", dragEnd);
}

// Normal selection, as opposed to text dragging.
function leftButtonSelect(cm, e, start, type, addNew) {
  var display = cm.display, doc = cm.doc;
  e_preventDefault(e);

  var ourRange, ourIndex, startSel = doc.sel;
  if (addNew && !e.shiftKey) {
    ourIndex = doc.sel.contains(start);
    if (ourIndex > -1)
      ourRange = doc.sel.ranges[ourIndex];
    else
      ourRange = new Range(start, start);
  } else {
    ourRange = doc.sel.primary();
  }

  if (e.altKey) {
    type = "rect";
    if (!addNew) ourRange = new Range(start, start);
    start = posFromMouse(cm, e, true, true);
    ourIndex = -1;
  } else if (type == "double") {
    var word = findWordAt(cm, start);
    if (cm.display.shift || doc.extend)
      ourRange = extendRange(doc, ourRange, word.anchor, word.head);
    else
      ourRange = word;
  } else if (type == "triple") {
    var line = new Range(Pos(start.line, 0), clipPos(doc, Pos(start.line + 1, 0)));
    if (cm.display.shift || doc.extend)
      ourRange = extendRange(doc, ourRange, line.anchor, line.head);
    else
      ourRange = line;
  } else {
    ourRange = extendRange(doc, ourRange, start);
  }

  if (!addNew) {
    ourIndex = 0;
    setSelection(doc, new Selection([ourRange], 0), sel_mouse);
    startSel = doc.sel;
  } else if (ourIndex > -1) {
    replaceOneSelection(doc, ourIndex, ourRange, sel_mouse);
  } else {
    ourIndex = doc.sel.ranges.length;
    setSelection(doc, normalizeSelection(doc.sel.ranges.concat([ourRange]), ourIndex),
                 {scroll: false, origin: "*mouse"});
  }

  var lastPos = start;
  function extendTo(pos) {
    if (cmp(lastPos, pos) == 0) return;
    lastPos = pos;

    if (type == "rect") {
      var ranges = [], tabSize = cm.options.tabSize;
      var startCol = countColumn(getLine(doc, start.line).text, start.ch, tabSize);
      var posCol = countColumn(getLine(doc, pos.line).text, pos.ch, tabSize);
      var left = Math.min(startCol, posCol), right = Math.max(startCol, posCol);
      for (var line = Math.min(start.line, pos.line), end = Math.min(cm.lastLine(), Math.max(start.line, pos.line));
           line <= end; line++) {
        var text = getLine(doc, line).text, leftPos = findColumn(text, left, tabSize);
        if (left == right)
          ranges.push(new Range(Pos(line, leftPos), Pos(line, leftPos)));
        else if (text.length > leftPos)
          ranges.push(new Range(Pos(line, leftPos), Pos(line, findColumn(text, right, tabSize))));
      }
      if (!ranges.length) ranges.push(new Range(start, start));
      setSelection(doc, normalizeSelection(startSel.ranges.slice(0, ourIndex).concat(ranges), ourIndex),
                   {origin: "*mouse", scroll: false});
      cm.scrollIntoView(pos);
    } else {
      var oldRange = ourRange;
      var anchor = oldRange.anchor, head = pos;
      if (type != "single") {
        if (type == "double")
          var range = findWordAt(cm, pos);
        else
          var range = new Range(Pos(pos.line, 0), clipPos(doc, Pos(pos.line + 1, 0)));
        if (cmp(range.anchor, anchor) > 0) {
          head = range.head;
          anchor = minPos(oldRange.from(), range.anchor);
        } else {
          head = range.anchor;
          anchor = maxPos(oldRange.to(), range.head);
        }
      }
      var ranges = startSel.ranges.slice(0);
      ranges[ourIndex] = new Range(clipPos(doc, anchor), head);
      setSelection(doc, normalizeSelection(ranges, ourIndex), sel_mouse);
    }
  }

  var editorSize = display.wrapper.getBoundingClientRect();
  // Used to ensure timeout re-tries don't fire when another extend
  // happened in the meantime (clearTimeout isn't reliable -- at
  // least on Chrome, the timeouts still happen even when cleared,
  // if the clear happens after their scheduled firing time).
  var counter = 0;

  function extend(e) {
    var curCount = ++counter;
    var cur = posFromMouse(cm, e, true, type == "rect");
    if (!cur) return;
    if (cmp(cur, lastPos) != 0) {
      ensureFocus(cm);
      extendTo(cur);
      var visible = visibleLines(display, doc);
      if (cur.line >= visible.to || cur.line < visible.from)
        setTimeout(operation(cm, function(){if (counter == curCount) extend(e);}), 150);
    } else {
      var outside = e.clientY < editorSize.top ? -20 : e.clientY > editorSize.bottom ? 20 : 0;
      if (outside) setTimeout(operation(cm, function() {
        if (counter != curCount) return;
        display.scroller.scrollTop += outside;
        extend(e);
      }), 50);
    }
  }

  function done(e) {
    counter = Infinity;
    e_preventDefault(e);
    focusInput(cm);
    off(document, "mousemove", move);
    off(document, "mouseup", up);
    doc.history.lastSelOrigin = null;
  }

  var move = operation(cm, function(e) {
    if (!e_button(e)) done(e);
    else extend(e);
  });
  var up = operation(cm, done);
  on(document, "mousemove", move);
  on(document, "mouseup", up);
}

// Determines whether an event happened in the gutter, and fires the
// handlers for the corresponding event.
function gutterEvent(cm, e, type, prevent, signalfn) {
  try { var mX = e.clientX, mY = e.clientY; }
  catch(e) { return false; }
  if (mX >= Math.floor(cm.display.gutters.getBoundingClientRect().right)) return false;
  if (prevent) e_preventDefault(e);

  var display = cm.display;
  var lineBox = display.lineDiv.getBoundingClientRect();

  if (mY > lineBox.bottom || !hasHandler(cm, type)) return e_defaultPrevented(e);
  mY -= lineBox.top - display.viewOffset;

  for (var i = 0; i < cm.options.gutters.length; ++i) {
    var g = display.gutters.childNodes[i];
    if (g && g.getBoundingClientRect().right >= mX) {
      var line = lineAtHeight(cm.doc, mY);
      var gutter = cm.options.gutters[i];
      signalfn(cm, type, cm, line, gutter, e);
      return e_defaultPrevented(e);
    }
  }
}

function clickInGutter(cm, e) {
  return gutterEvent(cm, e, "gutterClick", true, signalLater);
}

// Kludge to work around strange IE behavior where it'll sometimes
// re-fire a series of drag-related events right after the drop (#1551)
var lastDrop = 0;

function onDrop(e) {
  var cm = this;
  if (signalDOMEvent(cm, e) || eventInWidget(cm.display, e))
    return;
  e_preventDefault(e);
  if (ie) lastDrop = +new Date;
  var pos = posFromMouse(cm, e, true), files = e.dataTransfer.files;
  if (!pos || isReadOnly(cm)) return;
  // Might be a file drop, in which case we simply extract the text
  // and insert it.
  if (files && files.length && window.FileReader && window.File) {
    var n = files.length, text = Array(n), read = 0;
    var loadFile = function(file, i) {
      var reader = new FileReader;
      reader.onload = operation(cm, function() {
        text[i] = reader.result;
        if (++read == n) {
          pos = clipPos(cm.doc, pos);
          var change = {from: pos, to: pos, text: splitLines(text.join("\n")), origin: "paste"};
          makeChange(cm.doc, change);
          setSelectionReplaceHistory(cm.doc, simpleSelection(pos, changeEnd(change)));
        }
      });
      reader.readAsText(file);
    };
    for (var i = 0; i < n; ++i) loadFile(files[i], i);
  } else { // Normal drop
    // Don't do a replace if the drop happened inside of the selected text.
    if (cm.state.draggingText && cm.doc.sel.contains(pos) > -1) {
      cm.state.draggingText(e);
      // Ensure the editor is re-focused
      setTimeout(bind(focusInput, cm), 20);
      return;
    }
    try {
      var text = e.dataTransfer.getData("Text");
      if (text) {
        if (cm.state.draggingText && !(mac ? e.metaKey : e.ctrlKey))
          var selected = cm.listSelections();
        setSelectionNoUndo(cm.doc, simpleSelection(pos, pos));
        if (selected) for (var i = 0; i < selected.length; ++i)
          replaceRange(cm.doc, "", selected[i].anchor, selected[i].head, "drag");
        cm.replaceSelection(text, "around", "paste");
        focusInput(cm);
      }
    }
    catch(e){}
  }
}

function onDragStart(cm, e) {
  if (ie && (!cm.state.draggingText || +new Date - lastDrop < 100)) { e_stop(e); return; }
  if (signalDOMEvent(cm, e) || eventInWidget(cm.display, e)) return;

  e.dataTransfer.setData("Text", cm.getSelection());

  // Use dummy image instead of default browsers image.
  // Recent Safari (~6.0.2) have a tendency to segfault when this happens, so we don't do it there.
  if (e.dataTransfer.setDragImage && !safari) {
    var img = elt("img", null, null, "position: fixed; left: 0; top: 0;");
    img.src = "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";
    if (presto) {
      img.width = img.height = 1;
      cm.display.wrapper.appendChild(img);
      // Force a relayout, or Opera won't use our image for some obscure reason
      img._top = img.offsetTop;
    }
    e.dataTransfer.setDragImage(img, 0, 0);
    if (presto) img.parentNode.removeChild(img);
  }
}

// SCROLL EVENTS

// Sync the scrollable area and scrollbars, ensure the viewport
// covers the visible area.
function setScrollTop(cm, val) {
  if (Math.abs(cm.doc.scrollTop - val) < 2) return;
  cm.doc.scrollTop = val;
  if (!gecko) updateDisplaySimple(cm, {top: val});
  if (cm.display.scroller.scrollTop != val) cm.display.scroller.scrollTop = val;
  if (cm.display.scrollbarV.scrollTop != val) cm.display.scrollbarV.scrollTop = val;
  if (gecko) updateDisplaySimple(cm);
  startWorker(cm, 100);
}
// Sync scroller and scrollbar, ensure the gutter elements are
// aligned.
function setScrollLeft(cm, val, isScroller) {
  if (isScroller ? val == cm.doc.scrollLeft : Math.abs(cm.doc.scrollLeft - val) < 2) return;
  val = Math.min(val, cm.display.scroller.scrollWidth - cm.display.scroller.clientWidth);
  cm.doc.scrollLeft = val;
  alignHorizontally(cm);
  if (cm.display.scroller.scrollLeft != val) cm.display.scroller.scrollLeft = val;
  if (cm.display.scrollbarH.scrollLeft != val) cm.display.scrollbarH.scrollLeft = val;
}

// Since the delta values reported on mouse wheel events are
// unstandardized between browsers and even browser versions, and
// generally horribly unpredictable, this code starts by measuring
// the scroll effect that the first few mouse wheel events have,
// and, from that, detects the way it can convert deltas to pixel
// offsets afterwards.
//
// The reason we want to know the amount a wheel event will scroll
// is that it gives us a chance to update the display before the
// actual scrolling happens, reducing flickering.

var wheelSamples = 0, wheelPixelsPerUnit = null;
// Fill in a browser-detected starting value on browsers where we
// know one. These don't have to be accurate -- the result of them
// being wrong would just be a slight flicker on the first wheel
// scroll (if it is large enough).
if (ie) wheelPixelsPerUnit = -.53;
else if (gecko) wheelPixelsPerUnit = 15;
else if (chrome) wheelPixelsPerUnit = -.7;
else if (safari) wheelPixelsPerUnit = -1/3;

function onScrollWheel(cm, e) {
  var dx = e.wheelDeltaX, dy = e.wheelDeltaY;
  if (dx == null && e.detail && e.axis == e.HORIZONTAL_AXIS) dx = e.detail;
  if (dy == null && e.detail && e.axis == e.VERTICAL_AXIS) dy = e.detail;
  else if (dy == null) dy = e.wheelDelta;

  var display = cm.display, scroll = display.scroller;
  // Quit if there's nothing to scroll here
  if (!(dx && scroll.scrollWidth > scroll.clientWidth ||
        dy && scroll.scrollHeight > scroll.clientHeight)) return;

  // Webkit browsers on OS X abort momentum scrolls when the target
  // of the scroll event is removed from the scrollable element.
  // This hack (see related code in patchDisplay) makes sure the
  // element is kept around.
  if (dy && mac && webkit) {
    outer: for (var cur = e.target, view = display.view; cur != scroll; cur = cur.parentNode) {
      for (var i = 0; i < view.length; i++) {
        if (view[i].node == cur) {
          cm.display.currentWheelTarget = cur;
          break outer;
        }
      }
    }
  }

  // On some browsers, horizontal scrolling will cause redraws to
  // happen before the gutter has been realigned, causing it to
  // wriggle around in a most unseemly way. When we have an
  // estimated pixels/delta value, we just handle horizontal
  // scrolling entirely here. It'll be slightly off from native, but
  // better than glitching out.
  if (dx && !gecko && !presto && wheelPixelsPerUnit != null) {
    if (dy)
      setScrollTop(cm, Math.max(0, Math.min(scroll.scrollTop + dy * wheelPixelsPerUnit, scroll.scrollHeight - scroll.clientHeight)));
    setScrollLeft(cm, Math.max(0, Math.min(scroll.scrollLeft + dx * wheelPixelsPerUnit, scroll.scrollWidth - scroll.clientWidth)));
    e_preventDefault(e);
    display.wheelStartX = null; // Abort measurement, if in progress
    return;
  }

  // 'Project' the visible viewport to cover the area that is being
  // scrolled into view (if we know enough to estimate it).
  if (dy && wheelPixelsPerUnit != null) {
    var pixels = dy * wheelPixelsPerUnit;
    var top = cm.doc.scrollTop, bot = top + display.wrapper.clientHeight;
    if (pixels < 0) top = Math.max(0, top + pixels - 50);
    else bot = Math.min(cm.doc.height, bot + pixels + 50);
    updateDisplaySimple(cm, {top: top, bottom: bot});
  }

  if (wheelSamples < 20) {
    if (display.wheelStartX == null) {
      display.wheelStartX = scroll.scrollLeft; display.wheelStartY = scroll.scrollTop;
      display.wheelDX = dx; display.wheelDY = dy;
      setTimeout(function() {
        if (display.wheelStartX == null) return;
        var movedX = scroll.scrollLeft - display.wheelStartX;
        var movedY = scroll.scrollTop - display.wheelStartY;
        var sample = (movedY && display.wheelDY && movedY / display.wheelDY) ||
          (movedX && display.wheelDX && movedX / display.wheelDX);
        display.wheelStartX = display.wheelStartY = null;
        if (!sample) return;
        wheelPixelsPerUnit = (wheelPixelsPerUnit * wheelSamples + sample) / (wheelSamples + 1);
        ++wheelSamples;
      }, 200);
    } else {
      display.wheelDX += dx; display.wheelDY += dy;
    }
  }
}

// KEY EVENTS

// Run a handler that was bound to a key.
function doHandleBinding(cm, bound, dropShift) {
  if (typeof bound == "string") {
    bound = commands[bound];
    if (!bound) return false;
  }
  // Ensure previous input has been read, so that the handler sees a
  // consistent view of the document
  if (cm.display.pollingFast && readInput(cm)) cm.display.pollingFast = false;
  var prevShift = cm.display.shift, done = false;
  try {
    if (isReadOnly(cm)) cm.state.suppressEdits = true;
    if (dropShift) cm.display.shift = false;
    done = bound(cm) != Pass;
  } finally {
    cm.display.shift = prevShift;
    cm.state.suppressEdits = false;
  }
  return done;
}

// Collect the currently active keymaps.
function allKeyMaps(cm) {
  var maps = cm.state.keyMaps.slice(0);
  if (cm.options.extraKeys) maps.push(cm.options.extraKeys);
  maps.push(cm.options.keyMap);
  return maps;
}

var maybeTransition;
// Handle a key from the keydown event.
function handleKeyBinding(cm, e) {
  // Handle automatic keymap transitions
  var startMap = getKeyMap(cm.options.keyMap), next = startMap.auto;
  clearTimeout(maybeTransition);
  if (next && !isModifierKey(e)) maybeTransition = setTimeout(function() {
    if (getKeyMap(cm.options.keyMap) == startMap) {
      cm.options.keyMap = (next.call ? next.call(null, cm) : next);
      keyMapChanged(cm);
    }
  }, 50);

  var name = keyName(e, true), handled = false;
  if (!name) return false;
  var keymaps = allKeyMaps(cm);

  if (e.shiftKey) {
    // First try to resolve full name (including 'Shift-'). Failing
    // that, see if there is a cursor-motion command (starting with
    // 'go') bound to the keyname without 'Shift-'.
    handled = lookupKey("Shift-" + name, keymaps, function(b) {return doHandleBinding(cm, b, true);})
           || lookupKey(name, keymaps, function(b) {
                if (typeof b == "string" ? /^go[A-Z]/.test(b) : b.motion)
                  return doHandleBinding(cm, b);
              });
  } else {
    handled = lookupKey(name, keymaps, function(b) { return doHandleBinding(cm, b); });
  }

  if (handled) {
    e_preventDefault(e);
    restartBlink(cm);
    signalLater(cm, "keyHandled", cm, name, e);
  }
  return handled;
}

// Handle a key from the keypress event
function handleCharBinding(cm, e, ch) {
  var handled = lookupKey("'" + ch + "'", allKeyMaps(cm),
                          function(b) { return doHandleBinding(cm, b, true); });
  if (handled) {
    e_preventDefault(e);
    restartBlink(cm);
    signalLater(cm, "keyHandled", cm, "'" + ch + "'", e);
  }
  return handled;
}

var lastStoppedKey = null;
function onKeyDown(e) {
  var cm = this;
  ensureFocus(cm);
  if (signalDOMEvent(cm, e)) return;
  // IE does strange things with escape.
  if (ie && ie_version < 11 && e.keyCode == 27) e.returnValue = false;
  var code = e.keyCode;
  cm.display.shift = code == 16 || e.shiftKey;
  var handled = handleKeyBinding(cm, e);
  if (presto) {
    lastStoppedKey = handled ? code : null;
    // Opera has no cut event... we try to at least catch the key combo
    if (!handled && code == 88 && !hasCopyEvent && (mac ? e.metaKey : e.ctrlKey))
      cm.replaceSelection("", null, "cut");
  }

  // Turn mouse into crosshair when Alt is held on Mac.
  if (code == 18 && !/\bCodeMirror-crosshair\b/.test(cm.display.lineDiv.className))
    showCrossHair(cm);
}

function showCrossHair(cm) {
  var lineDiv = cm.display.lineDiv;
  addClass(lineDiv, "CodeMirror-crosshair");

  function up(e) {
    if (e.keyCode == 18 || !e.altKey) {
      rmClass(lineDiv, "CodeMirror-crosshair");
      off(document, "keyup", up);
      off(document, "mouseover", up);
    }
  }
  on(document, "keyup", up);
  on(document, "mouseover", up);
}

function onKeyUp(e) {
  if (e.keyCode == 16) this.doc.sel.shift = false;
  signalDOMEvent(this, e);
}

function onKeyPress(e) {
  var cm = this;
  if (signalDOMEvent(cm, e) || e.ctrlKey && !e.altKey || mac && e.metaKey) return;
  var keyCode = e.keyCode, charCode = e.charCode;
  if (presto && keyCode == lastStoppedKey) {lastStoppedKey = null; e_preventDefault(e); return;}
  if (((presto && (!e.which || e.which < 10)) || khtml) && handleKeyBinding(cm, e)) return;
  var ch = String.fromCharCode(charCode == null ? keyCode : charCode);
  if (handleCharBinding(cm, e, ch)) return;
  if (ie && ie_version >= 9) cm.display.inputHasSelection = null;
  fastPoll(cm);
}

// FOCUS/BLUR EVENTS

function onFocus(cm) {
  if (cm.options.readOnly == "nocursor") return;
  if (!cm.state.focused) {
    signal(cm, "focus", cm);
    cm.state.focused = true;
    addClass(cm.display.wrapper, "CodeMirror-focused");
    // The prevInput test prevents this from firing when a context
    // menu is closed (since the resetInput would kill the
    // select-all detection hack)
    if (!cm.curOp && cm.display.selForContextMenu != cm.doc.sel) {
      resetInput(cm);
      if (webkit) setTimeout(bind(resetInput, cm, true), 0); // Issue #1730
    }
  }
  slowPoll(cm);
  restartBlink(cm);
}
function onBlur(cm) {
  if (cm.state.focused) {
    signal(cm, "blur", cm);
    cm.state.focused = false;
    rmClass(cm.display.wrapper, "CodeMirror-focused");
  }
  clearInterval(cm.display.blinker);
  setTimeout(function() {if (!cm.state.focused) cm.display.shift = false;}, 150);
}

// CONTEXT MENU HANDLING

// To make the context menu work, we need to briefly unhide the
// textarea (making it as unobtrusive as possible) to let the
// right-click take effect on it.
function onContextMenu(cm, e) {
  if (signalDOMEvent(cm, e, "contextmenu")) return;
  var display = cm.display;
  if (eventInWidget(display, e) || contextMenuInGutter(cm, e)) return;

  var pos = posFromMouse(cm, e), scrollPos = display.scroller.scrollTop;
  if (!pos || presto) return; // Opera is difficult.

  // Reset the current text selection only if the click is done outside of the selection
  // and 'resetSelectionOnContextMenu' option is true.
  var reset = cm.options.resetSelectionOnContextMenu;
  if (reset && cm.doc.sel.contains(pos) == -1)
    operation(cm, setSelection)(cm.doc, simpleSelection(pos), sel_dontScroll);

  var oldCSS = display.input.style.cssText;
  display.inputDiv.style.position = "absolute";
  display.input.style.cssText = "position: fixed; width: 30px; height: 30px; top: " + (e.clientY - 5) +
    "px; left: " + (e.clientX - 5) + "px; z-index: 1000; background: " +
    (ie ? "rgba(255, 255, 255, .05)" : "transparent") +
    "; outline: none; border-width: 0; outline: none; overflow: hidden; opacity: .05; filter: alpha(opacity=5);";
  if (webkit) var oldScrollY = window.scrollY; // Work around Chrome issue (#2712)
  focusInput(cm);
  if (webkit) window.scrollTo(null, oldScrollY);
  resetInput(cm);
  // Adds "Select all" to context menu in FF
  if (!cm.somethingSelected()) display.input.value = display.prevInput = " ";
  display.selForContextMenu = cm.doc.sel;
  clearTimeout(display.detectingSelectAll);

  // Select-all will be greyed out if there's nothing to select, so
  // this adds a zero-width space so that we can later check whether
  // it got selected.
  function prepareSelectAllHack() {
    if (display.input.selectionStart != null) {
      var selected = cm.somethingSelected();
      var extval = display.input.value = "\u200b" + (selected ? display.input.value : "");
      display.prevInput = selected ? "" : "\u200b";
      display.input.selectionStart = 1; display.input.selectionEnd = extval.length;
      // Re-set this, in case some other handler touched the
      // selection in the meantime.
      display.selForContextMenu = cm.doc.sel;
    }
  }
  function rehide() {
    display.inputDiv.style.position = "relative";
    display.input.style.cssText = oldCSS;
    if (ie && ie_version < 9) display.scrollbarV.scrollTop = display.scroller.scrollTop = scrollPos;
    slowPoll(cm);

    // Try to detect the user choosing select-all
    if (display.input.selectionStart != null) {
      if (!ie || (ie && ie_version < 9)) prepareSelectAllHack();
      var i = 0, poll = function() {
        if (display.selForContextMenu == cm.doc.sel && display.input.selectionStart == 0)
          operation(cm, commands.selectAll)(cm);
        else if (i++ < 10) display.detectingSelectAll = setTimeout(poll, 500);
        else resetInput(cm);
      };
      display.detectingSelectAll = setTimeout(poll, 200);
    }
  }

  if (ie && ie_version >= 9) prepareSelectAllHack();
  if (captureRightClick) {
    e_stop(e);
    var mouseup = function() {
      off(window, "mouseup", mouseup);
      setTimeout(rehide, 20);
    };
    on(window, "mouseup", mouseup);
  } else {
    setTimeout(rehide, 50);
  }
}

function contextMenuInGutter(cm, e) {
  if (!hasHandler(cm, "gutterContextMenu")) return false;
  return gutterEvent(cm, e, "gutterContextMenu", false, signal);
}

// UPDATING

// Compute the position of the end of a change (its 'to' property
// refers to the pre-change end).
var changeEnd = CodeMirror.changeEnd = function(change) {
  if (!change.text) return change.to;
  return Pos(change.from.line + change.text.length - 1,
             lst(change.text).length + (change.text.length == 1 ? change.from.ch : 0));
};

// Adjust a position to refer to the post-change position of the
// same text, or the end of the change if the change covers it.
function adjustForChange(pos, change) {
  if (cmp(pos, change.from) < 0) return pos;
  if (cmp(pos, change.to) <= 0) return changeEnd(change);

  var line = pos.line + change.text.length - (change.to.line - change.from.line) - 1, ch = pos.ch;
  if (pos.line == change.to.line) ch += changeEnd(change).ch - change.to.ch;
  return Pos(line, ch);
}

function computeSelAfterChange(doc, change) {
  var out = [];
  for (var i = 0; i < doc.sel.ranges.length; i++) {
    var range = doc.sel.ranges[i];
    out.push(new Range(adjustForChange(range.anchor, change),
                       adjustForChange(range.head, change)));
  }
  return normalizeSelection(out, doc.sel.primIndex);
}

function offsetPos(pos, old, nw) {
  if (pos.line == old.line)
    return Pos(nw.line, pos.ch - old.ch + nw.ch);
  else
    return Pos(nw.line + (pos.line - old.line), pos.ch);
}

// Used by replaceSelections to allow moving the selection to the
// start or around the replaced test. Hint may be "start" or "around".
function computeReplacedSel(doc, changes, hint) {
  var out = [];
  var oldPrev = Pos(doc.first, 0), newPrev = oldPrev;
  for (var i = 0; i < changes.length; i++) {
    var change = changes[i];
    var from = offsetPos(change.from, oldPrev, newPrev);
    var to = offsetPos(changeEnd(change), oldPrev, newPrev);
    oldPrev = change.to;
    newPrev = to;
    if (hint == "around") {
      var range = doc.sel.ranges[i], inv = cmp(range.head, range.anchor) < 0;
      out[i] = new Range(inv ? to : from, inv ? from : to);
    } else {
      out[i] = new Range(from, from);
    }
  }
  return new Selection(out, doc.sel.primIndex);
}

// Allow "beforeChange" event handlers to influence a change
function filterChange(doc, change, update) {
  var obj = {
    canceled: false,
    from: change.from,
    to: change.to,
    text: change.text,
    origin: change.origin,
    cancel: function() { this.canceled = true; }
  };
  if (update) obj.update = function(from, to, text, origin) {
    if (from) this.from = clipPos(doc, from);
    if (to) this.to = clipPos(doc, to);
    if (text) this.text = text;
    if (origin !== undefined) this.origin = origin;
  };
  signal(doc, "beforeChange", doc, obj);
  if (doc.cm) signal(doc.cm, "beforeChange", doc.cm, obj);

  if (obj.canceled) return null;
  return {from: obj.from, to: obj.to, text: obj.text, origin: obj.origin};
}

// Apply a change to a document, and add it to the document's
// history, and propagating it to all linked documents.
function makeChange(doc, change, ignoreReadOnly) {
  if (doc.cm) {
    if (!doc.cm.curOp) return operation(doc.cm, makeChange)(doc, change, ignoreReadOnly);
    if (doc.cm.state.suppressEdits) return;
  }

  if (hasHandler(doc, "beforeChange") || doc.cm && hasHandler(doc.cm, "beforeChange")) {
    change = filterChange(doc, change, true);
    if (!change) return;
  }

  // Possibly split or suppress the update based on the presence
  // of read-only spans in its range.
  var split = sawReadOnlySpans && !ignoreReadOnly && removeReadOnlyRanges(doc, change.from, change.to);
  if (split) {
    for (var i = split.length - 1; i >= 0; --i)
      makeChangeInner(doc, {from: split[i].from, to: split[i].to, text: i ? [""] : change.text});
  } else {
    makeChangeInner(doc, change);
  }
}

function makeChangeInner(doc, change) {
  if (change.text.length == 1 && change.text[0] == "" && cmp(change.from, change.to) == 0) return;
  var selAfter = computeSelAfterChange(doc, change);
  addChangeToHistory(doc, change, selAfter, doc.cm ? doc.cm.curOp.id : NaN);

  makeChangeSingleDoc(doc, change, selAfter, stretchSpansOverChange(doc, change));
  var rebased = [];

  linkedDocs(doc, function(doc, sharedHist) {
    if (!sharedHist && indexOf(rebased, doc.history) == -1) {
      rebaseHist(doc.history, change);
      rebased.push(doc.history);
    }
    makeChangeSingleDoc(doc, change, null, stretchSpansOverChange(doc, change));
  });
}

// Revert a change stored in a document's history.
function makeChangeFromHistory(doc, type, allowSelectionOnly) {
  if (doc.cm && doc.cm.state.suppressEdits) return;

  var hist = doc.history, event, selAfter = doc.sel;
  var source = type == "undo" ? hist.done : hist.undone, dest = type == "undo" ? hist.undone : hist.done;

  // Verify that there is a useable event (so that ctrl-z won't
  // needlessly clear selection events)
  for (var i = 0; i < source.length; i++) {
    event = source[i];
    if (allowSelectionOnly ? event.ranges && !event.equals(doc.sel) : !event.ranges)
      break;
  }
  if (i == source.length) return;
  hist.lastOrigin = hist.lastSelOrigin = null;

  for (;;) {
    event = source.pop();
    if (event.ranges) {
      pushSelectionToHistory(event, dest);
      if (allowSelectionOnly && !event.equals(doc.sel)) {
        setSelection(doc, event, {clearRedo: false});
        return;
      }
      selAfter = event;
    }
    else break;
  }

  // Build up a reverse change object to add to the opposite history
  // stack (redo when undoing, and vice versa).
  var antiChanges = [];
  pushSelectionToHistory(selAfter, dest);
  dest.push({changes: antiChanges, generation: hist.generation});
  hist.generation = event.generation || ++hist.maxGeneration;

  var filter = hasHandler(doc, "beforeChange") || doc.cm && hasHandler(doc.cm, "beforeChange");

  for (var i = event.changes.length - 1; i >= 0; --i) {
    var change = event.changes[i];
    change.origin = type;
    if (filter && !filterChange(doc, change, false)) {
      source.length = 0;
      return;
    }

    antiChanges.push(historyChangeFromChange(doc, change));

    var after = i ? computeSelAfterChange(doc, change) : lst(source);
    makeChangeSingleDoc(doc, change, after, mergeOldSpans(doc, change));
    if (!i && doc.cm) doc.cm.scrollIntoView({from: change.from, to: changeEnd(change)});
    var rebased = [];

    // Propagate to the linked documents
    linkedDocs(doc, function(doc, sharedHist) {
      if (!sharedHist && indexOf(rebased, doc.history) == -1) {
        rebaseHist(doc.history, change);
        rebased.push(doc.history);
      }
      makeChangeSingleDoc(doc, change, null, mergeOldSpans(doc, change));
    });
  }
}

// Sub-views need their line numbers shifted when text is added
// above or below them in the parent document.
function shiftDoc(doc, distance) {
  if (distance == 0) return;
  doc.first += distance;
  doc.sel = new Selection(map(doc.sel.ranges, function(range) {
    return new Range(Pos(range.anchor.line + distance, range.anchor.ch),
                     Pos(range.head.line + distance, range.head.ch));
  }), doc.sel.primIndex);
  if (doc.cm) {
    regChange(doc.cm, doc.first, doc.first - distance, distance);
    for (var d = doc.cm.display, l = d.viewFrom; l < d.viewTo; l++)
      regLineChange(doc.cm, l, "gutter");
  }
}

// More lower-level change function, handling only a single document
// (not linked ones).
function makeChangeSingleDoc(doc, change, selAfter, spans) {
  if (doc.cm && !doc.cm.curOp)
    return operation(doc.cm, makeChangeSingleDoc)(doc, change, selAfter, spans);

  if (change.to.line < doc.first) {
    shiftDoc(doc, change.text.length - 1 - (change.to.line - change.from.line));
    return;
  }
  if (change.from.line > doc.lastLine()) return;

  // Clip the change to the size of this doc
  if (change.from.line < doc.first) {
    var shift = change.text.length - 1 - (doc.first - change.from.line);
    shiftDoc(doc, shift);
    change = {from: Pos(doc.first, 0), to: Pos(change.to.line + shift, change.to.ch),
              text: [lst(change.text)], origin: change.origin};
  }
  var last = doc.lastLine();
  if (change.to.line > last) {
    change = {from: change.from, to: Pos(last, getLine(doc, last).text.length),
              text: [change.text[0]], origin: change.origin};
  }

  change.removed = getBetween(doc, change.from, change.to);

  if (!selAfter) selAfter = computeSelAfterChange(doc, change);
  if (doc.cm) makeChangeSingleDocInEditor(doc.cm, change, spans);
  else updateDoc(doc, change, spans);
  setSelectionNoUndo(doc, selAfter, sel_dontScroll);
}

// Handle the interaction of a change to a document with the editor
// that this document is part of.
function makeChangeSingleDocInEditor(cm, change, spans) {
  var doc = cm.doc, display = cm.display, from = change.from, to = change.to;

  var recomputeMaxLength = false, checkWidthStart = from.line;
  if (!cm.options.lineWrapping) {
    checkWidthStart = lineNo(visualLine(getLine(doc, from.line)));
    doc.iter(checkWidthStart, to.line + 1, function(line) {
      if (line == display.maxLine) {
        recomputeMaxLength = true;
        return true;
      }
    });
  }

  if (doc.sel.contains(change.from, change.to) > -1)
    signalCursorActivity(cm);

  updateDoc(doc, change, spans, estimateHeight(cm));

  if (!cm.options.lineWrapping) {
    doc.iter(checkWidthStart, from.line + change.text.length, function(line) {
      var len = lineLength(line);
      if (len > display.maxLineLength) {
        display.maxLine = line;
        display.maxLineLength = len;
        display.maxLineChanged = true;
        recomputeMaxLength = false;
      }
    });
    if (recomputeMaxLength) cm.curOp.updateMaxLine = true;
  }

  // Adjust frontier, schedule worker
  doc.frontier = Math.min(doc.frontier, from.line);
  startWorker(cm, 400);

  var lendiff = change.text.length - (to.line - from.line) - 1;
  // Remember that these lines changed, for updating the display
  if (from.line == to.line && change.text.length == 1 && !isWholeLineUpdate(cm.doc, change))
    regLineChange(cm, from.line, "text");
  else
    regChange(cm, from.line, to.line + 1, lendiff);

  var changesHandler = hasHandler(cm, "changes"), changeHandler = hasHandler(cm, "change");
  if (changeHandler || changesHandler) {
    var obj = {
      from: from, to: to,
      text: change.text,
      removed: change.removed,
      origin: change.origin
    };
    if (changeHandler) signalLater(cm, "change", cm, obj);
    if (changesHandler) (cm.curOp.changeObjs || (cm.curOp.changeObjs = [])).push(obj);
  }
  cm.display.selForContextMenu = null;
}

function replaceRange(doc, code, from, to, origin) {
  if (!to) to = from;
  if (cmp(to, from) < 0) { var tmp = to; to = from; from = tmp; }
  if (typeof code == "string") code = splitLines(code);
  makeChange(doc, {from: from, to: to, text: code, origin: origin});
}

// SCROLLING THINGS INTO VIEW

// If an editor sits on the top or bottom of the window, partially
// scrolled out of view, this ensures that the cursor is visible.
function maybeScrollWindow(cm, coords) {
  var display = cm.display, box = display.sizer.getBoundingClientRect(), doScroll = null;
  if (coords.top + box.top < 0) doScroll = true;
  else if (coords.bottom + box.top > (window.innerHeight || document.documentElement.clientHeight)) doScroll = false;
  if (doScroll != null && !phantom) {
    var scrollNode = elt("div", "\u200b", null, "position: absolute; top: " +
                         (coords.top - display.viewOffset - paddingTop(cm.display)) + "px; height: " +
                         (coords.bottom - coords.top + scrollerCutOff) + "px; left: " +
                         coords.left + "px; width: 2px;");
    cm.display.lineSpace.appendChild(scrollNode);
    scrollNode.scrollIntoView(doScroll);
    cm.display.lineSpace.removeChild(scrollNode);
  }
}

// Scroll a given position into view (immediately), verifying that
// it actually became visible (as line heights are accurately
// measured, the position of something may 'drift' during drawing).
function scrollPosIntoView(cm, pos, end, margin) {
  if (margin == null) margin = 0;
  for (;;) {
    var changed = false, coords = cursorCoords(cm, pos);
    var endCoords = !end || end == pos ? coords : cursorCoords(cm, end);
    var scrollPos = calculateScrollPos(cm, Math.min(coords.left, endCoords.left),
                                       Math.min(coords.top, endCoords.top) - margin,
                                       Math.max(coords.left, endCoords.left),
                                       Math.max(coords.bottom, endCoords.bottom) + margin);
    var startTop = cm.doc.scrollTop, startLeft = cm.doc.scrollLeft;
    if (scrollPos.scrollTop != null) {
      setScrollTop(cm, scrollPos.scrollTop);
      if (Math.abs(cm.doc.scrollTop - startTop) > 1) changed = true;
    }
    if (scrollPos.scrollLeft != null) {
      setScrollLeft(cm, scrollPos.scrollLeft);
      if (Math.abs(cm.doc.scrollLeft - startLeft) > 1) changed = true;
    }
    if (!changed) return coords;
  }
}

// Scroll a given set of coordinates into view (immediately).
function scrollIntoView(cm, x1, y1, x2, y2) {
  var scrollPos = calculateScrollPos(cm, x1, y1, x2, y2);
  if (scrollPos.scrollTop != null) setScrollTop(cm, scrollPos.scrollTop);
  if (scrollPos.scrollLeft != null) setScrollLeft(cm, scrollPos.scrollLeft);
}

// Calculate a new scroll position needed to scroll the given
// rectangle into view. Returns an object with scrollTop and
// scrollLeft properties. When these are undefined, the
// vertical/horizontal position does not need to be adjusted.
function calculateScrollPos(cm, x1, y1, x2, y2) {
  var display = cm.display, snapMargin = textHeight(cm.display);
  if (y1 < 0) y1 = 0;
  var screentop = cm.curOp && cm.curOp.scrollTop != null ? cm.curOp.scrollTop : display.scroller.scrollTop;
  var screen = display.scroller.clientHeight - scrollerCutOff, result = {};
  if (y2 - y1 > screen) y2 = y1 + screen;
  var docBottom = cm.doc.height + paddingVert(display);
  var atTop = y1 < snapMargin, atBottom = y2 > docBottom - snapMargin;
  if (y1 < screentop) {
    result.scrollTop = atTop ? 0 : y1;
  } else if (y2 > screentop + screen) {
    var newTop = Math.min(y1, (atBottom ? docBottom : y2) - screen);
    if (newTop != screentop) result.scrollTop = newTop;
  }

  var screenleft = cm.curOp && cm.curOp.scrollLeft != null ? cm.curOp.scrollLeft : display.scroller.scrollLeft;
  var screenw = display.scroller.clientWidth - scrollerCutOff - display.gutters.offsetWidth;
  var tooWide = x2 - x1 > screenw;
  if (tooWide) x2 = y1 + screen;
  if (x1 < 10)
    result.scrollLeft = 0;
  else if (x1 < screenleft)
    result.scrollLeft = Math.max(0, x1 - (tooWide ? 0 : 10));
  else if (x2 > screenw + screenleft - 3)
    result.scrollLeft = x2 + (tooWide ? 0 : 10) - screenw;

  return result;
}

// Store a relative adjustment to the scroll position in the current
// operation (to be applied when the operation finishes).
function addToScrollPos(cm, left, top) {
  if (left != null || top != null) resolveScrollToPos(cm);
  if (left != null)
    cm.curOp.scrollLeft = (cm.curOp.scrollLeft == null ? cm.doc.scrollLeft : cm.curOp.scrollLeft) + left;
  if (top != null)
    cm.curOp.scrollTop = (cm.curOp.scrollTop == null ? cm.doc.scrollTop : cm.curOp.scrollTop) + top;
}

// Make sure that at the end of the operation the current cursor is
// shown.
function ensureCursorVisible(cm) {
  resolveScrollToPos(cm);
  var cur = cm.getCursor(), from = cur, to = cur;
  if (!cm.options.lineWrapping) {
    from = cur.ch ? Pos(cur.line, cur.ch - 1) : cur;
    to = Pos(cur.line, cur.ch + 1);
  }
  cm.curOp.scrollToPos = {from: from, to: to, margin: cm.options.cursorScrollMargin, isCursor: true};
}

// When an operation has its scrollToPos property set, and another
// scroll action is applied before the end of the operation, this
// 'simulates' scrolling that position into view in a cheap way, so
// that the effect of intermediate scroll commands is not ignored.
function resolveScrollToPos(cm) {
  var range = cm.curOp.scrollToPos;
  if (range) {
    cm.curOp.scrollToPos = null;
    var from = estimateCoords(cm, range.from), to = estimateCoords(cm, range.to);
    var sPos = calculateScrollPos(cm, Math.min(from.left, to.left),
                                  Math.min(from.top, to.top) - range.margin,
                                  Math.max(from.right, to.right),
                                  Math.max(from.bottom, to.bottom) + range.margin);
    cm.scrollTo(sPos.scrollLeft, sPos.scrollTop);
  }
}

// API UTILITIES

// Indent the given line. The how parameter can be "smart",
// "add"/null, "subtract", or "prev". When aggressive is false
// (typically set to true for forced single-line indents), empty
// lines are not indented, and places where the mode returns Pass
// are left alone.
function indentLine(cm, n, how, aggressive) {
  var doc = cm.doc, state;
  if (how == null) how = "add";
  if (how == "smart") {
    // Fall back to "prev" when the mode doesn't have an indentation
    // method.
    if (!doc.mode.indent) how = "prev";
    else state = getStateBefore(cm, n);
  }

  var tabSize = cm.options.tabSize;
  var line = getLine(doc, n), curSpace = countColumn(line.text, null, tabSize);
  if (line.stateAfter) line.stateAfter = null;
  var curSpaceString = line.text.match(/^\s*/)[0], indentation;
  if (!aggressive && !/\S/.test(line.text)) {
    indentation = 0;
    how = "not";
  } else if (how == "smart") {
    indentation = doc.mode.indent(state, line.text.slice(curSpaceString.length), line.text);
    if (indentation == Pass || indentation > 150) {
      if (!aggressive) return;
      how = "prev";
    }
  }
  if (how == "prev") {
    if (n > doc.first) indentation = countColumn(getLine(doc, n-1).text, null, tabSize);
    else indentation = 0;
  } else if (how == "add") {
    indentation = curSpace + cm.options.indentUnit;
  } else if (how == "subtract") {
    indentation = curSpace - cm.options.indentUnit;
  } else if (typeof how == "number") {
    indentation = curSpace + how;
  }
  indentation = Math.max(0, indentation);

  var indentString = "", pos = 0;
  if (cm.options.indentWithTabs)
    for (var i = Math.floor(indentation / tabSize); i; --i) {pos += tabSize; indentString += "\t";}
  if (pos < indentation) indentString += spaceStr(indentation - pos);

  if (indentString != curSpaceString) {
    replaceRange(doc, indentString, Pos(n, 0), Pos(n, curSpaceString.length), "+input");
  } else {
    // Ensure that, if the cursor was in the whitespace at the start
    // of the line, it is moved to the end of that space.
    for (var i = 0; i < doc.sel.ranges.length; i++) {
      var range = doc.sel.ranges[i];
      if (range.head.line == n && range.head.ch < curSpaceString.length) {
        var pos = Pos(n, curSpaceString.length);
        replaceOneSelection(doc, i, new Range(pos, pos));
        break;
      }
    }
  }
  line.stateAfter = null;
}

// Utility for applying a change to a line by handle or number,
// returning the number and optionally registering the line as
// changed.
function changeLine(doc, handle, changeType, op) {
  var no = handle, line = handle;
  if (typeof handle == "number") line = getLine(doc, clipLine(doc, handle));
  else no = lineNo(handle);
  if (no == null) return null;
  if (op(line, no) && doc.cm) regLineChange(doc.cm, no, changeType);
  return line;
}

// Helper for deleting text near the selection(s), used to implement
// backspace, delete, and similar functionality.
function deleteNearSelection(cm, compute) {
  var ranges = cm.doc.sel.ranges, kill = [];
  // Build up a set of ranges to kill first, merging overlapping
  // ranges.
  for (var i = 0; i < ranges.length; i++) {
    var toKill = compute(ranges[i]);
    while (kill.length && cmp(toKill.from, lst(kill).to) <= 0) {
      var replaced = kill.pop();
      if (cmp(replaced.from, toKill.from) < 0) {
        toKill.from = replaced.from;
        break;
      }
    }
    kill.push(toKill);
  }
  // Next, remove those actual ranges.
  runInOp(cm, function() {
    for (var i = kill.length - 1; i >= 0; i--)
      replaceRange(cm.doc, "", kill[i].from, kill[i].to, "+delete");
    ensureCursorVisible(cm);
  });
}

// Used for horizontal relative motion. Dir is -1 or 1 (left or
// right), unit can be "char", "column" (like char, but doesn't
// cross line boundaries), "word" (across next word), or "group" (to
// the start of next group of word or non-word-non-whitespace
// chars). The visually param controls whether, in right-to-left
// text, direction 1 means to move towards the next index in the
// string, or towards the character to the right of the current
// position. The resulting position will have a hitSide=true
// property if it reached the end of the document.
function findPosH(doc, pos, dir, unit, visually) {
  var line = pos.line, ch = pos.ch, origDir = dir;
  var lineObj = getLine(doc, line);
  var possible = true;
  function findNextLine() {
    var l = line + dir;
    if (l < doc.first || l >= doc.first + doc.size) return (possible = false);
    line = l;
    return lineObj = getLine(doc, l);
  }
  function moveOnce(boundToLine) {
    var next = (visually ? moveVisually : moveLogically)(lineObj, ch, dir, true);
    if (next == null) {
      if (!boundToLine && findNextLine()) {
        if (visually) ch = (dir < 0 ? lineRight : lineLeft)(lineObj);
        else ch = dir < 0 ? lineObj.text.length : 0;
      } else return (possible = false);
    } else ch = next;
    return true;
  }

  if (unit == "char") moveOnce();
  else if (unit == "column") moveOnce(true);
  else if (unit == "word" || unit == "group") {
    var sawType = null, group = unit == "group";
    var helper = doc.cm && doc.cm.getHelper(pos, "wordChars");
    for (var first = true;; first = false) {
      if (dir < 0 && !moveOnce(!first)) break;
      var cur = lineObj.text.charAt(ch) || "\n";
      var type = isWordChar(cur, helper) ? "w"
        : group && cur == "\n" ? "n"
        : !group || /\s/.test(cur) ? null
        : "p";
      if (group && !first && !type) type = "s";
      if (sawType && sawType != type) {
        if (dir < 0) {dir = 1; moveOnce();}
        break;
      }

      if (type) sawType = type;
      if (dir > 0 && !moveOnce(!first)) break;
    }
  }
  var result = skipAtomic(doc, Pos(line, ch), origDir, true);
  if (!possible) result.hitSide = true;
  return result;
}

// For relative vertical movement. Dir may be -1 or 1. Unit can be
// "page" or "line". The resulting position will have a hitSide=true
// property if it reached the end of the document.
function findPosV(cm, pos, dir, unit) {
  var doc = cm.doc, x = pos.left, y;
  if (unit == "page") {
    var pageSize = Math.min(cm.display.wrapper.clientHeight, window.innerHeight || document.documentElement.clientHeight);
    y = pos.top + dir * (pageSize - (dir < 0 ? 1.5 : .5) * textHeight(cm.display));
  } else if (unit == "line") {
    y = dir > 0 ? pos.bottom + 3 : pos.top - 3;
  }
  for (;;) {
    var target = coordsChar(cm, x, y);
    if (!target.outside) break;
    if (dir < 0 ? y <= 0 : y >= doc.height) { target.hitSide = true; break; }
    y += dir * 5;
  }
  return target;
}

// Find the word at the given position (as returned by coordsChar).
function findWordAt(cm, pos) {
  var doc = cm.doc, line = getLine(doc, pos.line).text;
  var start = pos.ch, end = pos.ch;
  if (line) {
    var helper = cm.getHelper(pos, "wordChars");
    if ((pos.xRel < 0 || end == line.length) && start) --start; else ++end;
    var startChar = line.charAt(start);
    var check = isWordChar(startChar, helper)
      ? function(ch) { return isWordChar(ch, helper); }
      : /\s/.test(startChar) ? function(ch) {return /\s/.test(ch);}
      : function(ch) {return !/\s/.test(ch) && !isWordChar(ch);};
    while (start > 0 && check(line.charAt(start - 1))) --start;
    while (end < line.length && check(line.charAt(end))) ++end;
  }
  return new Range(Pos(pos.line, start), Pos(pos.line, end));
}

// EDITOR METHODS

// The publicly visible API. Note that methodOp(f) means
// 'wrap f in an operation, performed on its `this` parameter'.

// This is not the complete set of editor methods. Most of the
// methods defined on the Doc type are also injected into
// CodeMirror.prototype, for backwards compatibility and
// convenience.

CodeMirror.prototype = {
  constructor: CodeMirror,
  focus: function(){window.focus(); focusInput(this); fastPoll(this);},

  setOption: function(option, value) {
    var options = this.options, old = options[option];
    if (options[option] == value && option != "mode") return;
    options[option] = value;
    if (optionHandlers.hasOwnProperty(option))
      operation(this, optionHandlers[option])(this, value, old);
  },

  getOption: function(option) {return this.options[option];},
  getDoc: function() {return this.doc;},

  addKeyMap: function(map, bottom) {
    this.state.keyMaps[bottom ? "push" : "unshift"](map);
  },
  removeKeyMap: function(map) {
    var maps = this.state.keyMaps;
    for (var i = 0; i < maps.length; ++i)
      if (maps[i] == map || (typeof maps[i] != "string" && maps[i].name == map)) {
        maps.splice(i, 1);
        return true;
      }
  },

  addOverlay: methodOp(function(spec, options) {
    var mode = spec.token ? spec : CodeMirror.getMode(this.options, spec);
    if (mode.startState) throw new Error("Overlays may not be stateful.");
    this.state.overlays.push({mode: mode, modeSpec: spec, opaque: options && options.opaque});
    this.state.modeGen++;
    regChange(this);
  }),
  removeOverlay: methodOp(function(spec) {
    var overlays = this.state.overlays;
    for (var i = 0; i < overlays.length; ++i) {
      var cur = overlays[i].modeSpec;
      if (cur == spec || typeof spec == "string" && cur.name == spec) {
        overlays.splice(i, 1);
        this.state.modeGen++;
        regChange(this);
        return;
      }
    }
  }),

  indentLine: methodOp(function(n, dir, aggressive) {
    if (typeof dir != "string" && typeof dir != "number") {
      if (dir == null) dir = this.options.smartIndent ? "smart" : "prev";
      else dir = dir ? "add" : "subtract";
    }
    if (isLine(this.doc, n)) indentLine(this, n, dir, aggressive);
  }),
  indentSelection: methodOp(function(how) {
    var ranges = this.doc.sel.ranges, end = -1;
    for (var i = 0; i < ranges.length; i++) {
      var range = ranges[i];
      if (!range.empty()) {
        var from = range.from(), to = range.to();
        var start = Math.max(end, from.line);
        end = Math.min(this.lastLine(), to.line - (to.ch ? 0 : 1)) + 1;
        for (var j = start; j < end; ++j)
          indentLine(this, j, how);
        var newRanges = this.doc.sel.ranges;
        if (from.ch == 0 && ranges.length == newRanges.length && newRanges[i].from().ch > 0)
          replaceOneSelection(this.doc, i, new Range(from, newRanges[i].to()), sel_dontScroll);
      } else if (range.head.line > end) {
        indentLine(this, range.head.line, how, true);
        end = range.head.line;
        if (i == this.doc.sel.primIndex) ensureCursorVisible(this);
      }
    }
  }),

  // Fetch the parser token for a given character. Useful for hacks
  // that want to inspect the mode state (say, for completion).
  getTokenAt: function(pos, precise) {
    var doc = this.doc;
    pos = clipPos(doc, pos);
    var state = getStateBefore(this, pos.line, precise), mode = this.doc.mode;
    var line = getLine(doc, pos.line);
    var stream = new StringStream(line.text, this.options.tabSize);
    while (stream.pos < pos.ch && !stream.eol()) {
      stream.start = stream.pos;
      var style = readToken(mode, stream, state);
    }
    return {start: stream.start,
            end: stream.pos,
            string: stream.current(),
            type: style || null,
            state: state};
  },

  getTokenTypeAt: function(pos) {
    pos = clipPos(this.doc, pos);
    var styles = getLineStyles(this, getLine(this.doc, pos.line));
    var before = 0, after = (styles.length - 1) / 2, ch = pos.ch;
    var type;
    if (ch == 0) type = styles[2];
    else for (;;) {
      var mid = (before + after) >> 1;
      if ((mid ? styles[mid * 2 - 1] : 0) >= ch) after = mid;
      else if (styles[mid * 2 + 1] < ch) before = mid + 1;
      else { type = styles[mid * 2 + 2]; break; }
    }
    var cut = type ? type.indexOf("cm-overlay ") : -1;
    return cut < 0 ? type : cut == 0 ? null : type.slice(0, cut - 1);
  },

  getModeAt: function(pos) {
    var mode = this.doc.mode;
    if (!mode.innerMode) return mode;
    return CodeMirror.innerMode(mode, this.getTokenAt(pos).state).mode;
  },

  getHelper: function(pos, type) {
    return this.getHelpers(pos, type)[0];
  },

  getHelpers: function(pos, type) {
    var found = [];
    if (!helpers.hasOwnProperty(type)) return helpers;
    var help = helpers[type], mode = this.getModeAt(pos);
    if (typeof mode[type] == "string") {
      if (help[mode[type]]) found.push(help[mode[type]]);
    } else if (mode[type]) {
      for (var i = 0; i < mode[type].length; i++) {
        var val = help[mode[type][i]];
        if (val) found.push(val);
      }
    } else if (mode.helperType && help[mode.helperType]) {
      found.push(help[mode.helperType]);
    } else if (help[mode.name]) {
      found.push(help[mode.name]);
    }
    for (var i = 0; i < help._global.length; i++) {
      var cur = help._global[i];
      if (cur.pred(mode, this) && indexOf(found, cur.val) == -1)
        found.push(cur.val);
    }
    return found;
  },

  getStateAfter: function(line, precise) {
    var doc = this.doc;
    line = clipLine(doc, line == null ? doc.first + doc.size - 1: line);
    return getStateBefore(this, line + 1, precise);
  },

  cursorCoords: function(start, mode) {
    var pos, range = this.doc.sel.primary();
    if (start == null) pos = range.head;
    else if (typeof start == "object") pos = clipPos(this.doc, start);
    else pos = start ? range.from() : range.to();
    return cursorCoords(this, pos, mode || "page");
  },

  charCoords: function(pos, mode) {
    return charCoords(this, clipPos(this.doc, pos), mode || "page");
  },

  coordsChar: function(coords, mode) {
    coords = fromCoordSystem(this, coords, mode || "page");
    return coordsChar(this, coords.left, coords.top);
  },

  lineAtHeight: function(height, mode) {
    height = fromCoordSystem(this, {top: height, left: 0}, mode || "page").top;
    return lineAtHeight(this.doc, height + this.display.viewOffset);
  },
  heightAtLine: function(line, mode) {
    var end = false, last = this.doc.first + this.doc.size - 1;
    if (line < this.doc.first) line = this.doc.first;
    else if (line > last) { line = last; end = true; }
    var lineObj = getLine(this.doc, line);
    return intoCoordSystem(this, lineObj, {top: 0, left: 0}, mode || "page").top +
      (end ? this.doc.height - heightAtLine(lineObj) : 0);
  },

  defaultTextHeight: function() { return textHeight(this.display); },
  defaultCharWidth: function() { return charWidth(this.display); },

  setGutterMarker: methodOp(function(line, gutterID, value) {
    return changeLine(this.doc, line, "gutter", function(line) {
      var markers = line.gutterMarkers || (line.gutterMarkers = {});
      markers[gutterID] = value;
      if (!value && isEmpty(markers)) line.gutterMarkers = null;
      return true;
    });
  }),

  clearGutter: methodOp(function(gutterID) {
    var cm = this, doc = cm.doc, i = doc.first;
    doc.iter(function(line) {
      if (line.gutterMarkers && line.gutterMarkers[gutterID]) {
        line.gutterMarkers[gutterID] = null;
        regLineChange(cm, i, "gutter");
        if (isEmpty(line.gutterMarkers)) line.gutterMarkers = null;
      }
      ++i;
    });
  }),

  addLineWidget: methodOp(function(handle, node, options) {
    return addLineWidget(this, handle, node, options);
  }),

  removeLineWidget: function(widget) { widget.clear(); },

  lineInfo: function(line) {
    if (typeof line == "number") {
      if (!isLine(this.doc, line)) return null;
      var n = line;
      line = getLine(this.doc, line);
      if (!line) return null;
    } else {
      var n = lineNo(line);
      if (n == null) return null;
    }
    return {line: n, handle: line, text: line.text, gutterMarkers: line.gutterMarkers,
            textClass: line.textClass, bgClass: line.bgClass, wrapClass: line.wrapClass,
            widgets: line.widgets};
  },

  getViewport: function() { return {from: this.display.viewFrom, to: this.display.viewTo};},

  addWidget: function(pos, node, scroll, vert, horiz) {
    var display = this.display;
    pos = cursorCoords(this, clipPos(this.doc, pos));
    var top = pos.bottom, left = pos.left;
    node.style.position = "absolute";
    display.sizer.appendChild(node);
    if (vert == "over") {
      top = pos.top;
    } else if (vert == "above" || vert == "near") {
      var vspace = Math.max(display.wrapper.clientHeight, this.doc.height),
      hspace = Math.max(display.sizer.clientWidth, display.lineSpace.clientWidth);
      // Default to positioning above (if specified and possible); otherwise default to positioning below
      if ((vert == 'above' || pos.bottom + node.offsetHeight > vspace) && pos.top > node.offsetHeight)
        top = pos.top - node.offsetHeight;
      else if (pos.bottom + node.offsetHeight <= vspace)
        top = pos.bottom;
      if (left + node.offsetWidth > hspace)
        left = hspace - node.offsetWidth;
    }
    node.style.top = top + "px";
    node.style.left = node.style.right = "";
    if (horiz == "right") {
      left = display.sizer.clientWidth - node.offsetWidth;
      node.style.right = "0px";
    } else {
      if (horiz == "left") left = 0;
      else if (horiz == "middle") left = (display.sizer.clientWidth - node.offsetWidth) / 2;
      node.style.left = left + "px";
    }
    if (scroll)
      scrollIntoView(this, left, top, left + node.offsetWidth, top + node.offsetHeight);
  },

  triggerOnKeyDown: methodOp(onKeyDown),
  triggerOnKeyPress: methodOp(onKeyPress),
  triggerOnKeyUp: onKeyUp,

  execCommand: function(cmd) {
    if (commands.hasOwnProperty(cmd))
      return commands[cmd](this);
  },

  findPosH: function(from, amount, unit, visually) {
    var dir = 1;
    if (amount < 0) { dir = -1; amount = -amount; }
    for (var i = 0, cur = clipPos(this.doc, from); i < amount; ++i) {
      cur = findPosH(this.doc, cur, dir, unit, visually);
      if (cur.hitSide) break;
    }
    return cur;
  },

  moveH: methodOp(function(dir, unit) {
    var cm = this;
    cm.extendSelectionsBy(function(range) {
      if (cm.display.shift || cm.doc.extend || range.empty())
        return findPosH(cm.doc, range.head, dir, unit, cm.options.rtlMoveVisually);
      else
        return dir < 0 ? range.from() : range.to();
    }, sel_move);
  }),

  deleteH: methodOp(function(dir, unit) {
    var sel = this.doc.sel, doc = this.doc;
    if (sel.somethingSelected())
      doc.replaceSelection("", null, "+delete");
    else
      deleteNearSelection(this, function(range) {
        var other = findPosH(doc, range.head, dir, unit, false);
        return dir < 0 ? {from: other, to: range.head} : {from: range.head, to: other};
      });
  }),

  findPosV: function(from, amount, unit, goalColumn) {
    var dir = 1, x = goalColumn;
    if (amount < 0) { dir = -1; amount = -amount; }
    for (var i = 0, cur = clipPos(this.doc, from); i < amount; ++i) {
      var coords = cursorCoords(this, cur, "div");
      if (x == null) x = coords.left;
      else coords.left = x;
      cur = findPosV(this, coords, dir, unit);
      if (cur.hitSide) break;
    }
    return cur;
  },

  moveV: methodOp(function(dir, unit) {
    var cm = this, doc = this.doc, goals = [];
    var collapse = !cm.display.shift && !doc.extend && doc.sel.somethingSelected();
    doc.extendSelectionsBy(function(range) {
      if (collapse)
        return dir < 0 ? range.from() : range.to();
      var headPos = cursorCoords(cm, range.head, "div");
      if (range.goalColumn != null) headPos.left = range.goalColumn;
      goals.push(headPos.left);
      var pos = findPosV(cm, headPos, dir, unit);
      if (unit == "page" && range == doc.sel.primary())
        addToScrollPos(cm, null, charCoords(cm, pos, "div").top - headPos.top);
      return pos;
    }, sel_move);
    if (goals.length) for (var i = 0; i < doc.sel.ranges.length; i++)
      doc.sel.ranges[i].goalColumn = goals[i];
  }),

  toggleOverwrite: function(value) {
    if (value != null && value == this.state.overwrite) return;
    if (this.state.overwrite = !this.state.overwrite)
      addClass(this.display.cursorDiv, "CodeMirror-overwrite");
    else
      rmClass(this.display.cursorDiv, "CodeMirror-overwrite");

    signal(this, "overwriteToggle", this, this.state.overwrite);
  },
  hasFocus: function() { return activeElt() == this.display.input; },

  scrollTo: methodOp(function(x, y) {
    if (x != null || y != null) resolveScrollToPos(this);
    if (x != null) this.curOp.scrollLeft = x;
    if (y != null) this.curOp.scrollTop = y;
  }),
  getScrollInfo: function() {
    var scroller = this.display.scroller, co = scrollerCutOff;
    return {left: scroller.scrollLeft, top: scroller.scrollTop,
            height: scroller.scrollHeight - co, width: scroller.scrollWidth - co,
            clientHeight: scroller.clientHeight - co, clientWidth: scroller.clientWidth - co};
  },

  scrollIntoView: methodOp(function(range, margin) {
    if (range == null) {
      range = {from: this.doc.sel.primary().head, to: null};
      if (margin == null) margin = this.options.cursorScrollMargin;
    } else if (typeof range == "number") {
      range = {from: Pos(range, 0), to: null};
    } else if (range.from == null) {
      range = {from: range, to: null};
    }
    if (!range.to) range.to = range.from;
    range.margin = margin || 0;

    if (range.from.line != null) {
      resolveScrollToPos(this);
      this.curOp.scrollToPos = range;
    } else {
      var sPos = calculateScrollPos(this, Math.min(range.from.left, range.to.left),
                                    Math.min(range.from.top, range.to.top) - range.margin,
                                    Math.max(range.from.right, range.to.right),
                                    Math.max(range.from.bottom, range.to.bottom) + range.margin);
      this.scrollTo(sPos.scrollLeft, sPos.scrollTop);
    }
  }),

  setSize: methodOp(function(width, height) {
    var cm = this;
    function interpret(val) {
      return typeof val == "number" || /^\d+$/.test(String(val)) ? val + "px" : val;
    }
    if (width != null) cm.display.wrapper.style.width = interpret(width);
    if (height != null) cm.display.wrapper.style.height = interpret(height);
    if (cm.options.lineWrapping) clearLineMeasurementCache(this);
    var lineNo = cm.display.viewFrom;
    cm.doc.iter(lineNo, cm.display.viewTo, function(line) {
      if (line.widgets) for (var i = 0; i < line.widgets.length; i++)
        if (line.widgets[i].noHScroll) { regLineChange(cm, lineNo, "widget"); break; }
      ++lineNo;
    });
    cm.curOp.forceUpdate = true;
    signal(cm, "refresh", this);
  }),

  operation: function(f){return runInOp(this, f);},

  refresh: methodOp(function() {
    var oldHeight = this.display.cachedTextHeight;
    regChange(this);
    this.curOp.forceUpdate = true;
    clearCaches(this);
    this.scrollTo(this.doc.scrollLeft, this.doc.scrollTop);
    updateGutterSpace(this);
    if (oldHeight == null || Math.abs(oldHeight - textHeight(this.display)) > .5)
      estimateLineHeights(this);
    signal(this, "refresh", this);
  }),

  swapDoc: methodOp(function(doc) {
    var old = this.doc;
    old.cm = null;
    attachDoc(this, doc);
    clearCaches(this);
    resetInput(this);
    this.scrollTo(doc.scrollLeft, doc.scrollTop);
    signalLater(this, "swapDoc", this, old);
    return old;
  }),

  getInputField: function(){return this.display.input;},
  getWrapperElement: function(){return this.display.wrapper;},
  getScrollerElement: function(){return this.display.scroller;},
  getGutterElement: function(){return this.display.gutters;}
};
eventMixin(CodeMirror);

// OPTION DEFAULTS

// The default configuration options.
var defaults = CodeMirror.defaults = {};
// Functions to run when options are changed.
var optionHandlers = CodeMirror.optionHandlers = {};

function option(name, deflt, handle, notOnInit) {
  CodeMirror.defaults[name] = deflt;
  if (handle) optionHandlers[name] =
    notOnInit ? function(cm, val, old) {if (old != Init) handle(cm, val, old);} : handle;
}

// Passed to option handlers when there is no old value.
var Init = CodeMirror.Init = {toString: function(){return "CodeMirror.Init";}};

// These two are, on init, called from the constructor because they
// have to be initialized before the editor can start at all.
option("value", "", function(cm, val) {
  cm.setValue(val);
}, true);
option("mode", null, function(cm, val) {
  cm.doc.modeOption = val;
  loadMode(cm);
}, true);

option("indentUnit", 2, loadMode, true);
option("indentWithTabs", false);
option("smartIndent", true);
option("tabSize", 4, function(cm) {
  resetModeState(cm);
  clearCaches(cm);
  regChange(cm);
}, true);
option("specialChars", /[\t\u0000-\u0019\u00ad\u200b-\u200f\u2028\u2029\ufeff]/g, function(cm, val) {
  cm.options.specialChars = new RegExp(val.source + (val.test("\t") ? "" : "|\t"), "g");
  cm.refresh();
}, true);
option("specialCharPlaceholder", defaultSpecialCharPlaceholder, function(cm) {cm.refresh();}, true);
option("electricChars", true);
option("rtlMoveVisually", !windows);
option("wholeLineUpdateBefore", true);

option("theme", "default", function(cm) {
  themeChanged(cm);
  guttersChanged(cm);
}, true);
option("keyMap", "default", keyMapChanged);
option("extraKeys", null);

option("lineWrapping", false, wrappingChanged, true);
option("gutters", [], function(cm) {
  setGuttersForLineNumbers(cm.options);
  guttersChanged(cm);
}, true);
option("fixedGutter", true, function(cm, val) {
  cm.display.gutters.style.left = val ? compensateForHScroll(cm.display) + "px" : "0";
  cm.refresh();
}, true);
option("coverGutterNextToScrollbar", false, updateScrollbars, true);
option("lineNumbers", false, function(cm) {
  setGuttersForLineNumbers(cm.options);
  guttersChanged(cm);
}, true);
option("firstLineNumber", 1, guttersChanged, true);
option("lineNumberFormatter", function(integer) {return integer;}, guttersChanged, true);
option("showCursorWhenSelecting", false, updateSelection, true);

option("resetSelectionOnContextMenu", true);

option("readOnly", false, function(cm, val) {
  if (val == "nocursor") {
    onBlur(cm);
    cm.display.input.blur();
    cm.display.disabled = true;
  } else {
    cm.display.disabled = false;
    if (!val) resetInput(cm);
  }
});
option("disableInput", false, function(cm, val) {if (!val) resetInput(cm);}, true);
option("dragDrop", true);

option("cursorBlinkRate", 530);
option("cursorScrollMargin", 0);
option("cursorHeight", 1, updateSelection, true);
option("singleCursorHeightPerLine", true, updateSelection, true);
option("workTime", 100);
option("workDelay", 100);
option("flattenSpans", true, resetModeState, true);
option("addModeClass", false, resetModeState, true);
option("pollInterval", 100);
option("undoDepth", 200, function(cm, val){cm.doc.history.undoDepth = val;});
option("historyEventDelay", 1250);
option("viewportMargin", 10, function(cm){cm.refresh();}, true);
option("maxHighlightLength", 10000, resetModeState, true);
option("moveInputWithCursor", true, function(cm, val) {
  if (!val) cm.display.inputDiv.style.top = cm.display.inputDiv.style.left = 0;
});

option("tabindex", null, function(cm, val) {
  cm.display.input.tabIndex = val || "";
});
option("autofocus", null);

// MODE DEFINITION AND QUERYING

// Known modes, by name and by MIME
var modes = CodeMirror.modes = {}, mimeModes = CodeMirror.mimeModes = {};

// Extra arguments are stored as the mode's dependencies, which is
// used by (legacy) mechanisms like loadmode.js to automatically
// load a mode. (Preferred mechanism is the require/define calls.)
CodeMirror.defineMode = function(name, mode) {
  if (!CodeMirror.defaults.mode && name != "null") CodeMirror.defaults.mode = name;
  if (arguments.length > 2) {
    mode.dependencies = [];
    for (var i = 2; i < arguments.length; ++i) mode.dependencies.push(arguments[i]);
  }
  modes[name] = mode;
};

CodeMirror.defineMIME = function(mime, spec) {
  mimeModes[mime] = spec;
};

// Given a MIME type, a {name, ...options} config object, or a name
// string, return a mode config object.
CodeMirror.resolveMode = function(spec) {
  if (typeof spec == "string" && mimeModes.hasOwnProperty(spec)) {
    spec = mimeModes[spec];
  } else if (spec && typeof spec.name == "string" && mimeModes.hasOwnProperty(spec.name)) {
    var found = mimeModes[spec.name];
    if (typeof found == "string") found = {name: found};
    spec = createObj(found, spec);
    spec.name = found.name;
  } else if (typeof spec == "string" && /^[\w\-]+\/[\w\-]+\+xml$/.test(spec)) {
    return CodeMirror.resolveMode("application/xml");
  }
  if (typeof spec == "string") return {name: spec};
  else return spec || {name: "null"};
};

// Given a mode spec (anything that resolveMode accepts), find and
// initialize an actual mode object.
CodeMirror.getMode = function(options, spec) {
  var spec = CodeMirror.resolveMode(spec);
  var mfactory = modes[spec.name];
  if (!mfactory) return CodeMirror.getMode(options, "text/plain");
  var modeObj = mfactory(options, spec);
  if (modeExtensions.hasOwnProperty(spec.name)) {
    var exts = modeExtensions[spec.name];
    for (var prop in exts) {
      if (!exts.hasOwnProperty(prop)) continue;
      if (modeObj.hasOwnProperty(prop)) modeObj["_" + prop] = modeObj[prop];
      modeObj[prop] = exts[prop];
    }
  }
  modeObj.name = spec.name;
  if (spec.helperType) modeObj.helperType = spec.helperType;
  if (spec.modeProps) for (var prop in spec.modeProps)
    modeObj[prop] = spec.modeProps[prop];

  return modeObj;
};

// Minimal default mode.
CodeMirror.defineMode("null", function() {
  return {token: function(stream) {stream.skipToEnd();}};
});
CodeMirror.defineMIME("text/plain", "null");

// This can be used to attach properties to mode objects from
// outside the actual mode definition.
var modeExtensions = CodeMirror.modeExtensions = {};
CodeMirror.extendMode = function(mode, properties) {
  var exts = modeExtensions.hasOwnProperty(mode) ? modeExtensions[mode] : (modeExtensions[mode] = {});
  copyObj(properties, exts);
};

// EXTENSIONS

CodeMirror.defineExtension = function(name, func) {
  CodeMirror.prototype[name] = func;
};
CodeMirror.defineDocExtension = function(name, func) {
  Doc.prototype[name] = func;
};
CodeMirror.defineOption = option;

var initHooks = [];
CodeMirror.defineInitHook = function(f) {initHooks.push(f);};

var helpers = CodeMirror.helpers = {};
CodeMirror.registerHelper = function(type, name, value) {
  if (!helpers.hasOwnProperty(type)) helpers[type] = CodeMirror[type] = {_global: []};
  helpers[type][name] = value;
};
CodeMirror.registerGlobalHelper = function(type, name, predicate, value) {
  CodeMirror.registerHelper(type, name, value);
  helpers[type]._global.push({pred: predicate, val: value});
};

// MODE STATE HANDLING

// Utility functions for working with state. Exported because nested
// modes need to do this for their inner modes.

var copyState = CodeMirror.copyState = function(mode, state) {
  if (state === true) return state;
  if (mode.copyState) return mode.copyState(state);
  var nstate = {};
  for (var n in state) {
    var val = state[n];
    if (val instanceof Array) val = val.concat([]);
    nstate[n] = val;
  }
  return nstate;
};

var startState = CodeMirror.startState = function(mode, a1, a2) {
  return mode.startState ? mode.startState(a1, a2) : true;
};

// Given a mode and a state (for that mode), find the inner mode and
// state at the position that the state refers to.
CodeMirror.innerMode = function(mode, state) {
  while (mode.innerMode) {
    var info = mode.innerMode(state);
    if (!info || info.mode == mode) break;
    state = info.state;
    mode = info.mode;
  }
  return info || {mode: mode, state: state};
};

// STANDARD COMMANDS

// Commands are parameter-less actions that can be performed on an
// editor, mostly used for keybindings.
var commands = CodeMirror.commands = {
  selectAll: function(cm) {cm.setSelection(Pos(cm.firstLine(), 0), Pos(cm.lastLine()), sel_dontScroll);},
  singleSelection: function(cm) {
    cm.setSelection(cm.getCursor("anchor"), cm.getCursor("head"), sel_dontScroll);
  },
  killLine: function(cm) {
    deleteNearSelection(cm, function(range) {
      if (range.empty()) {
        var len = getLine(cm.doc, range.head.line).text.length;
        if (range.head.ch == len && range.head.line < cm.lastLine())
          return {from: range.head, to: Pos(range.head.line + 1, 0)};
        else
          return {from: range.head, to: Pos(range.head.line, len)};
      } else {
        return {from: range.from(), to: range.to()};
      }
    });
  },
  deleteLine: function(cm) {
    deleteNearSelection(cm, function(range) {
      return {from: Pos(range.from().line, 0),
              to: clipPos(cm.doc, Pos(range.to().line + 1, 0))};
    });
  },
  delLineLeft: function(cm) {
    deleteNearSelection(cm, function(range) {
      return {from: Pos(range.from().line, 0), to: range.from()};
    });
  },
  delWrappedLineLeft: function(cm) {
    deleteNearSelection(cm, function(range) {
      var top = cm.charCoords(range.head, "div").top + 5;
      var leftPos = cm.coordsChar({left: 0, top: top}, "div");
      return {from: leftPos, to: range.from()};
    });
  },
  delWrappedLineRight: function(cm) {
    deleteNearSelection(cm, function(range) {
      var top = cm.charCoords(range.head, "div").top + 5;
      var rightPos = cm.coordsChar({left: cm.display.lineDiv.offsetWidth + 100, top: top}, "div");
      return {from: range.from(), to: rightPos };
    });
  },
  undo: function(cm) {cm.undo();},
  redo: function(cm) {cm.redo();},
  undoSelection: function(cm) {cm.undoSelection();},
  redoSelection: function(cm) {cm.redoSelection();},
  goDocStart: function(cm) {cm.extendSelection(Pos(cm.firstLine(), 0));},
  goDocEnd: function(cm) {cm.extendSelection(Pos(cm.lastLine()));},
  goLineStart: function(cm) {
    cm.extendSelectionsBy(function(range) { return lineStart(cm, range.head.line); },
                          {origin: "+move", bias: 1});
  },
  goLineStartSmart: function(cm) {
    cm.extendSelectionsBy(function(range) {
      return lineStartSmart(cm, range.head);
    }, {origin: "+move", bias: 1});
  },
  goLineEnd: function(cm) {
    cm.extendSelectionsBy(function(range) { return lineEnd(cm, range.head.line); },
                          {origin: "+move", bias: -1});
  },
  goLineRight: function(cm) {
    cm.extendSelectionsBy(function(range) {
      var top = cm.charCoords(range.head, "div").top + 5;
      return cm.coordsChar({left: cm.display.lineDiv.offsetWidth + 100, top: top}, "div");
    }, sel_move);
  },
  goLineLeft: function(cm) {
    cm.extendSelectionsBy(function(range) {
      var top = cm.charCoords(range.head, "div").top + 5;
      return cm.coordsChar({left: 0, top: top}, "div");
    }, sel_move);
  },
  goLineLeftSmart: function(cm) {
    cm.extendSelectionsBy(function(range) {
      var top = cm.charCoords(range.head, "div").top + 5;
      var pos = cm.coordsChar({left: 0, top: top}, "div");
      if (pos.ch < cm.getLine(pos.line).search(/\S/)) return lineStartSmart(cm, range.head);
      return pos;
    }, sel_move);
  },
  goLineUp: function(cm) {cm.moveV(-1, "line");},
  goLineDown: function(cm) {cm.moveV(1, "line");},
  goPageUp: function(cm) {cm.moveV(-1, "page");},
  goPageDown: function(cm) {cm.moveV(1, "page");},
  goCharLeft: function(cm) {cm.moveH(-1, "char");},
  goCharRight: function(cm) {cm.moveH(1, "char");},
  goColumnLeft: function(cm) {cm.moveH(-1, "column");},
  goColumnRight: function(cm) {cm.moveH(1, "column");},
  goWordLeft: function(cm) {cm.moveH(-1, "word");},
  goGroupRight: function(cm) {cm.moveH(1, "group");},
  goGroupLeft: function(cm) {cm.moveH(-1, "group");},
  goWordRight: function(cm) {cm.moveH(1, "word");},
  delCharBefore: function(cm) {cm.deleteH(-1, "char");},
  delCharAfter: function(cm) {cm.deleteH(1, "char");},
  delWordBefore: function(cm) {cm.deleteH(-1, "word");},
  delWordAfter: function(cm) {cm.deleteH(1, "word");},
  delGroupBefore: function(cm) {cm.deleteH(-1, "group");},
  delGroupAfter: function(cm) {cm.deleteH(1, "group");},
  indentAuto: function(cm) {cm.indentSelection("smart");},
  indentMore: function(cm) {cm.indentSelection("add");},
  indentLess: function(cm) {cm.indentSelection("subtract");},
  insertTab: function(cm) {cm.replaceSelection("\t");},
  insertSoftTab: function(cm) {
    var spaces = [], ranges = cm.listSelections(), tabSize = cm.options.tabSize;
    for (var i = 0; i < ranges.length; i++) {
      var pos = ranges[i].from();
      var col = countColumn(cm.getLine(pos.line), pos.ch, tabSize);
      spaces.push(new Array(tabSize - col % tabSize + 1).join(" "));
    }
    cm.replaceSelections(spaces);
  },
  defaultTab: function(cm) {
    if (cm.somethingSelected()) cm.indentSelection("add");
    else cm.execCommand("insertTab");
  },
  transposeChars: function(cm) {
    runInOp(cm, function() {
      var ranges = cm.listSelections(), newSel = [];
      for (var i = 0; i < ranges.length; i++) {
        var cur = ranges[i].head, line = getLine(cm.doc, cur.line).text;
        if (line) {
          if (cur.ch == line.length) cur = new Pos(cur.line, cur.ch - 1);
          if (cur.ch > 0) {
            cur = new Pos(cur.line, cur.ch + 1);
            cm.replaceRange(line.charAt(cur.ch - 1) + line.charAt(cur.ch - 2),
                            Pos(cur.line, cur.ch - 2), cur, "+transpose");
          } else if (cur.line > cm.doc.first) {
            var prev = getLine(cm.doc, cur.line - 1).text;
            if (prev)
              cm.replaceRange(line.charAt(0) + "\n" + prev.charAt(prev.length - 1),
                              Pos(cur.line - 1, prev.length - 1), Pos(cur.line, 1), "+transpose");
          }
        }
        newSel.push(new Range(cur, cur));
      }
      cm.setSelections(newSel);
    });
  },
  newlineAndIndent: function(cm) {
    runInOp(cm, function() {
      var len = cm.listSelections().length;
      for (var i = 0; i < len; i++) {
        var range = cm.listSelections()[i];
        cm.replaceRange("\n", range.anchor, range.head, "+input");
        cm.indentLine(range.from().line + 1, null, true);
        ensureCursorVisible(cm);
      }
    });
  },
  toggleOverwrite: function(cm) {cm.toggleOverwrite();}
};

// STANDARD KEYMAPS

var keyMap = CodeMirror.keyMap = {};
keyMap.basic = {
  "Left": "goCharLeft", "Right": "goCharRight", "Up": "goLineUp", "Down": "goLineDown",
  "End": "goLineEnd", "Home": "goLineStartSmart", "PageUp": "goPageUp", "PageDown": "goPageDown",
  "Delete": "delCharAfter", "Backspace": "delCharBefore", "Shift-Backspace": "delCharBefore",
  "Tab": "defaultTab", "Shift-Tab": "indentAuto",
  "Enter": "newlineAndIndent", "Insert": "toggleOverwrite",
  "Esc": "singleSelection"
};
// Note that the save and find-related commands aren't defined by
// default. User code or addons can define them. Unknown commands
// are simply ignored.
keyMap.pcDefault = {
  "Ctrl-A": "selectAll", "Ctrl-D": "deleteLine", "Ctrl-Z": "undo", "Shift-Ctrl-Z": "redo", "Ctrl-Y": "redo",
  "Ctrl-Home": "goDocStart", "Ctrl-Up": "goDocStart", "Ctrl-End": "goDocEnd", "Ctrl-Down": "goDocEnd",
  "Ctrl-Left": "goGroupLeft", "Ctrl-Right": "goGroupRight", "Alt-Left": "goLineStart", "Alt-Right": "goLineEnd",
  "Ctrl-Backspace": "delGroupBefore", "Ctrl-Delete": "delGroupAfter", "Ctrl-S": "save", "Ctrl-F": "find",
  "Ctrl-G": "findNext", "Shift-Ctrl-G": "findPrev", "Shift-Ctrl-F": "replace", "Shift-Ctrl-R": "replaceAll",
  "Ctrl-[": "indentLess", "Ctrl-]": "indentMore",
  "Ctrl-U": "undoSelection", "Shift-Ctrl-U": "redoSelection", "Alt-U": "redoSelection",
  fallthrough: "basic"
};
keyMap.macDefault = {
  "Cmd-A": "selectAll", "Cmd-D": "deleteLine", "Cmd-Z": "undo", "Shift-Cmd-Z": "redo", "Cmd-Y": "redo",
  "Cmd-Home": "goDocStart", "Cmd-Up": "goDocStart", "Cmd-End": "goDocEnd", "Cmd-Down": "goDocEnd", "Alt-Left": "goGroupLeft",
  "Alt-Right": "goGroupRight", "Cmd-Left": "goLineLeft", "Cmd-Right": "goLineRight", "Alt-Backspace": "delGroupBefore",
  "Ctrl-Alt-Backspace": "delGroupAfter", "Alt-Delete": "delGroupAfter", "Cmd-S": "save", "Cmd-F": "find",
  "Cmd-G": "findNext", "Shift-Cmd-G": "findPrev", "Cmd-Alt-F": "replace", "Shift-Cmd-Alt-F": "replaceAll",
  "Cmd-[": "indentLess", "Cmd-]": "indentMore", "Cmd-Backspace": "delWrappedLineLeft", "Cmd-Delete": "delWrappedLineRight",
  "Cmd-U": "undoSelection", "Shift-Cmd-U": "redoSelection",
  fallthrough: ["basic", "emacsy"]
};
// Very basic readline/emacs-style bindings, which are standard on Mac.
keyMap.emacsy = {
  "Ctrl-F": "goCharRight", "Ctrl-B": "goCharLeft", "Ctrl-P": "goLineUp", "Ctrl-N": "goLineDown",
  "Alt-F": "goWordRight", "Alt-B": "goWordLeft", "Ctrl-A": "goLineStart", "Ctrl-E": "goLineEnd",
  "Ctrl-V": "goPageDown", "Shift-Ctrl-V": "goPageUp", "Ctrl-D": "delCharAfter", "Ctrl-H": "delCharBefore",
  "Alt-D": "delWordAfter", "Alt-Backspace": "delWordBefore", "Ctrl-K": "killLine", "Ctrl-T": "transposeChars"
};
keyMap["default"] = mac ? keyMap.macDefault : keyMap.pcDefault;

// KEYMAP DISPATCH

function getKeyMap(val) {
  if (typeof val == "string") return keyMap[val];
  else return val;
}

// Given an array of keymaps and a key name, call handle on any
// bindings found, until that returns a truthy value, at which point
// we consider the key handled. Implements things like binding a key
// to false stopping further handling and keymap fallthrough.
var lookupKey = CodeMirror.lookupKey = function(name, maps, handle) {
  function lookup(map) {
    map = getKeyMap(map);
    var found = map[name];
    if (found === false) return "stop";
    if (found != null && handle(found)) return true;
    if (map.nofallthrough) return "stop";

    var fallthrough = map.fallthrough;
    if (fallthrough == null) return false;
    if (Object.prototype.toString.call(fallthrough) != "[object Array]")
      return lookup(fallthrough);
    for (var i = 0; i < fallthrough.length; ++i) {
      var done = lookup(fallthrough[i]);
      if (done) return done;
    }
    return false;
  }

  for (var i = 0; i < maps.length; ++i) {
    var done = lookup(maps[i]);
    if (done) return done != "stop";
  }
};

// Modifier key presses don't count as 'real' key presses for the
// purpose of keymap fallthrough.
var isModifierKey = CodeMirror.isModifierKey = function(event) {
  var name = keyNames[event.keyCode];
  return name == "Ctrl" || name == "Alt" || name == "Shift" || name == "Mod";
};

// Look up the name of a key as indicated by an event object.
var keyName = CodeMirror.keyName = function(event, noShift) {
  if (presto && event.keyCode == 34 && event["char"]) return false;
  var name = keyNames[event.keyCode];
  if (name == null || event.altGraphKey) return false;
  if (event.altKey) name = "Alt-" + name;
  if (flipCtrlCmd ? event.metaKey : event.ctrlKey) name = "Ctrl-" + name;
  if (flipCtrlCmd ? event.ctrlKey : event.metaKey) name = "Cmd-" + name;
  if (!noShift && event.shiftKey) name = "Shift-" + name;
  return name;
};

// FROMTEXTAREA

CodeMirror.fromTextArea = function(textarea, options) {
  if (!options) options = {};
  options.value = textarea.value;
  if (!options.tabindex && textarea.tabindex)
    options.tabindex = textarea.tabindex;
  if (!options.placeholder && textarea.placeholder)
    options.placeholder = textarea.placeholder;
  // Set autofocus to true if this textarea is focused, or if it has
  // autofocus and no other element is focused.
  if (options.autofocus == null) {
    var hasFocus = activeElt();
    options.autofocus = hasFocus == textarea ||
      textarea.getAttribute("autofocus") != null && hasFocus == document.body;
  }

  function save() {textarea.value = cm.getValue();}
  if (textarea.form) {
    on(textarea.form, "submit", save);
    // Deplorable hack to make the submit method do the right thing.
    if (!options.leaveSubmitMethodAlone) {
      var form = textarea.form, realSubmit = form.submit;
      try {
        var wrappedSubmit = form.submit = function() {
          save();
          form.submit = realSubmit;
          form.submit();
          form.submit = wrappedSubmit;
        };
      } catch(e) {}
    }
  }

  textarea.style.display = "none";
  var cm = CodeMirror(function(node) {
    textarea.parentNode.insertBefore(node, textarea.nextSibling);
  }, options);
  cm.save = save;
  cm.getTextArea = function() { return textarea; };
  cm.toTextArea = function() {
    save();
    textarea.parentNode.removeChild(cm.getWrapperElement());
    textarea.style.display = "";
    if (textarea.form) {
      off(textarea.form, "submit", save);
      if (typeof textarea.form.submit == "function")
        textarea.form.submit = realSubmit;
    }
  };
  return cm;
};

// STRING STREAM

// Fed to the mode parsers, provides helper functions to make
// parsers more succinct.

var StringStream = CodeMirror.StringStream = function(string, tabSize) {
  this.pos = this.start = 0;
  this.string = string;
  this.tabSize = tabSize || 8;
  this.lastColumnPos = this.lastColumnValue = 0;
  this.lineStart = 0;
};

StringStream.prototype = {
  eol: function() {return this.pos >= this.string.length;},
  sol: function() {return this.pos == this.lineStart;},
  peek: function() {return this.string.charAt(this.pos) || undefined;},
  next: function() {
    if (this.pos < this.string.length)
      return this.string.charAt(this.pos++);
  },
  eat: function(match) {
    var ch = this.string.charAt(this.pos);
    if (typeof match == "string") var ok = ch == match;
    else var ok = ch && (match.test ? match.test(ch) : match(ch));
    if (ok) {++this.pos; return ch;}
  },
  eatWhile: function(match) {
    var start = this.pos;
    while (this.eat(match)){}
    return this.pos > start;
  },
  eatSpace: function() {
    var start = this.pos;
    while (/[\s\u00a0]/.test(this.string.charAt(this.pos))) ++this.pos;
    return this.pos > start;
  },
  skipToEnd: function() {this.pos = this.string.length;},
  skipTo: function(ch) {
    var found = this.string.indexOf(ch, this.pos);
    if (found > -1) {this.pos = found; return true;}
  },
  backUp: function(n) {this.pos -= n;},
  column: function() {
    if (this.lastColumnPos < this.start) {
      this.lastColumnValue = countColumn(this.string, this.start, this.tabSize, this.lastColumnPos, this.lastColumnValue);
      this.lastColumnPos = this.start;
    }
    return this.lastColumnValue - (this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0);
  },
  indentation: function() {
    return countColumn(this.string, null, this.tabSize) -
      (this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0);
  },
  match: function(pattern, consume, caseInsensitive) {
    if (typeof pattern == "string") {
      var cased = function(str) {return caseInsensitive ? str.toLowerCase() : str;};
      var substr = this.string.substr(this.pos, pattern.length);
      if (cased(substr) == cased(pattern)) {
        if (consume !== false) this.pos += pattern.length;
        return true;
      }
    } else {
      var match = this.string.slice(this.pos).match(pattern);
      if (match && match.index > 0) return null;
      if (match && consume !== false) this.pos += match[0].length;
      return match;
    }
  },
  current: function(){return this.string.slice(this.start, this.pos);},
  hideFirstChars: function(n, inner) {
    this.lineStart += n;
    try { return inner(); }
    finally { this.lineStart -= n; }
  }
};

// TEXTMARKERS

// Created with markText and setBookmark methods. A TextMarker is a
// handle that can be used to clear or find a marked position in the
// document. Line objects hold arrays (markedSpans) containing
// {from, to, marker} object pointing to such marker objects, and
// indicating that such a marker is present on that line. Multiple
// lines may point to the same marker when it spans across lines.
// The spans will have null for their from/to properties when the
// marker continues beyond the start/end of the line. Markers have
// links back to the lines they currently touch.

var TextMarker = CodeMirror.TextMarker = function(doc, type) {
  this.lines = [];
  this.type = type;
  this.doc = doc;
};
eventMixin(TextMarker);

// Clear the marker.
TextMarker.prototype.clear = function() {
  if (this.explicitlyCleared) return;
  var cm = this.doc.cm, withOp = cm && !cm.curOp;
  if (withOp) startOperation(cm);
  if (hasHandler(this, "clear")) {
    var found = this.find();
    if (found) signalLater(this, "clear", found.from, found.to);
  }
  var min = null, max = null;
  for (var i = 0; i < this.lines.length; ++i) {
    var line = this.lines[i];
    var span = getMarkedSpanFor(line.markedSpans, this);
    if (cm && !this.collapsed) regLineChange(cm, lineNo(line), "text");
    else if (cm) {
      if (span.to != null) max = lineNo(line);
      if (span.from != null) min = lineNo(line);
    }
    line.markedSpans = removeMarkedSpan(line.markedSpans, span);
    if (span.from == null && this.collapsed && !lineIsHidden(this.doc, line) && cm)
      updateLineHeight(line, textHeight(cm.display));
  }
  if (cm && this.collapsed && !cm.options.lineWrapping) for (var i = 0; i < this.lines.length; ++i) {
    var visual = visualLine(this.lines[i]), len = lineLength(visual);
    if (len > cm.display.maxLineLength) {
      cm.display.maxLine = visual;
      cm.display.maxLineLength = len;
      cm.display.maxLineChanged = true;
    }
  }

  if (min != null && cm && this.collapsed) regChange(cm, min, max + 1);
  this.lines.length = 0;
  this.explicitlyCleared = true;
  if (this.atomic && this.doc.cantEdit) {
    this.doc.cantEdit = false;
    if (cm) reCheckSelection(cm.doc);
  }
  if (cm) signalLater(cm, "markerCleared", cm, this);
  if (withOp) endOperation(cm);
  if (this.parent) this.parent.clear();
};

// Find the position of the marker in the document. Returns a {from,
// to} object by default. Side can be passed to get a specific side
// -- 0 (both), -1 (left), or 1 (right). When lineObj is true, the
// Pos objects returned contain a line object, rather than a line
// number (used to prevent looking up the same line twice).
TextMarker.prototype.find = function(side, lineObj) {
  if (side == null && this.type == "bookmark") side = 1;
  var from, to;
  for (var i = 0; i < this.lines.length; ++i) {
    var line = this.lines[i];
    var span = getMarkedSpanFor(line.markedSpans, this);
    if (span.from != null) {
      from = Pos(lineObj ? line : lineNo(line), span.from);
      if (side == -1) return from;
    }
    if (span.to != null) {
      to = Pos(lineObj ? line : lineNo(line), span.to);
      if (side == 1) return to;
    }
  }
  return from && {from: from, to: to};
};

// Signals that the marker's widget changed, and surrounding layout
// should be recomputed.
TextMarker.prototype.changed = function() {
  var pos = this.find(-1, true), widget = this, cm = this.doc.cm;
  if (!pos || !cm) return;
  runInOp(cm, function() {
    var line = pos.line, lineN = lineNo(pos.line);
    var view = findViewForLine(cm, lineN);
    if (view) {
      clearLineMeasurementCacheFor(view);
      cm.curOp.selectionChanged = cm.curOp.forceUpdate = true;
    }
    cm.curOp.updateMaxLine = true;
    if (!lineIsHidden(widget.doc, line) && widget.height != null) {
      var oldHeight = widget.height;
      widget.height = null;
      var dHeight = widgetHeight(widget) - oldHeight;
      if (dHeight)
        updateLineHeight(line, line.height + dHeight);
    }
  });
};

TextMarker.prototype.attachLine = function(line) {
  if (!this.lines.length && this.doc.cm) {
    var op = this.doc.cm.curOp;
    if (!op.maybeHiddenMarkers || indexOf(op.maybeHiddenMarkers, this) == -1)
      (op.maybeUnhiddenMarkers || (op.maybeUnhiddenMarkers = [])).push(this);
  }
  this.lines.push(line);
};
TextMarker.prototype.detachLine = function(line) {
  this.lines.splice(indexOf(this.lines, line), 1);
  if (!this.lines.length && this.doc.cm) {
    var op = this.doc.cm.curOp;
    (op.maybeHiddenMarkers || (op.maybeHiddenMarkers = [])).push(this);
  }
};

// Collapsed markers have unique ids, in order to be able to order
// them, which is needed for uniquely determining an outer marker
// when they overlap (they may nest, but not partially overlap).
var nextMarkerId = 0;

// Create a marker, wire it up to the right lines, and
function markText(doc, from, to, options, type) {
  // Shared markers (across linked documents) are handled separately
  // (markTextShared will call out to this again, once per
  // document).
  if (options && options.shared) return markTextShared(doc, from, to, options, type);
  // Ensure we are in an operation.
  if (doc.cm && !doc.cm.curOp) return operation(doc.cm, markText)(doc, from, to, options, type);

  var marker = new TextMarker(doc, type), diff = cmp(from, to);
  if (options) copyObj(options, marker, false);
  // Don't connect empty markers unless clearWhenEmpty is false
  if (diff > 0 || diff == 0 && marker.clearWhenEmpty !== false)
    return marker;
  if (marker.replacedWith) {
    // Showing up as a widget implies collapsed (widget replaces text)
    marker.collapsed = true;
    marker.widgetNode = elt("span", [marker.replacedWith], "CodeMirror-widget");
    if (!options.handleMouseEvents) marker.widgetNode.ignoreEvents = true;
    if (options.insertLeft) marker.widgetNode.insertLeft = true;
  }
  if (marker.collapsed) {
    if (conflictingCollapsedRange(doc, from.line, from, to, marker) ||
        from.line != to.line && conflictingCollapsedRange(doc, to.line, from, to, marker))
      throw new Error("Inserting collapsed marker partially overlapping an existing one");
    sawCollapsedSpans = true;
  }

  if (marker.addToHistory)
    addChangeToHistory(doc, {from: from, to: to, origin: "markText"}, doc.sel, NaN);

  var curLine = from.line, cm = doc.cm, updateMaxLine;
  doc.iter(curLine, to.line + 1, function(line) {
    if (cm && marker.collapsed && !cm.options.lineWrapping && visualLine(line) == cm.display.maxLine)
      updateMaxLine = true;
    if (marker.collapsed && curLine != from.line) updateLineHeight(line, 0);
    addMarkedSpan(line, new MarkedSpan(marker,
                                       curLine == from.line ? from.ch : null,
                                       curLine == to.line ? to.ch : null));
    ++curLine;
  });
  // lineIsHidden depends on the presence of the spans, so needs a second pass
  if (marker.collapsed) doc.iter(from.line, to.line + 1, function(line) {
    if (lineIsHidden(doc, line)) updateLineHeight(line, 0);
  });

  if (marker.clearOnEnter) on(marker, "beforeCursorEnter", function() { marker.clear(); });

  if (marker.readOnly) {
    sawReadOnlySpans = true;
    if (doc.history.done.length || doc.history.undone.length)
      doc.clearHistory();
  }
  if (marker.collapsed) {
    marker.id = ++nextMarkerId;
    marker.atomic = true;
  }
  if (cm) {
    // Sync editor state
    if (updateMaxLine) cm.curOp.updateMaxLine = true;
    if (marker.collapsed)
      regChange(cm, from.line, to.line + 1);
    else if (marker.className || marker.title || marker.startStyle || marker.endStyle)
      for (var i = from.line; i <= to.line; i++) regLineChange(cm, i, "text");
    if (marker.atomic) reCheckSelection(cm.doc);
    signalLater(cm, "markerAdded", cm, marker);
  }
  return marker;
}

// SHARED TEXTMARKERS

// A shared marker spans multiple linked documents. It is
// implemented as a meta-marker-object controlling multiple normal
// markers.
var SharedTextMarker = CodeMirror.SharedTextMarker = function(markers, primary) {
  this.markers = markers;
  this.primary = primary;
  for (var i = 0; i < markers.length; ++i)
    markers[i].parent = this;
};
eventMixin(SharedTextMarker);

SharedTextMarker.prototype.clear = function() {
  if (this.explicitlyCleared) return;
  this.explicitlyCleared = true;
  for (var i = 0; i < this.markers.length; ++i)
    this.markers[i].clear();
  signalLater(this, "clear");
};
SharedTextMarker.prototype.find = function(side, lineObj) {
  return this.primary.find(side, lineObj);
};

function markTextShared(doc, from, to, options, type) {
  options = copyObj(options);
  options.shared = false;
  var markers = [markText(doc, from, to, options, type)], primary = markers[0];
  var widget = options.widgetNode;
  linkedDocs(doc, function(doc) {
    if (widget) options.widgetNode = widget.cloneNode(true);
    markers.push(markText(doc, clipPos(doc, from), clipPos(doc, to), options, type));
    for (var i = 0; i < doc.linked.length; ++i)
      if (doc.linked[i].isParent) return;
    primary = lst(markers);
  });
  return new SharedTextMarker(markers, primary);
}

function findSharedMarkers(doc) {
  return doc.findMarks(Pos(doc.first, 0), doc.clipPos(Pos(doc.lastLine())),
                       function(m) { return m.parent; });
}

function copySharedMarkers(doc, markers) {
  for (var i = 0; i < markers.length; i++) {
    var marker = markers[i], pos = marker.find();
    var mFrom = doc.clipPos(pos.from), mTo = doc.clipPos(pos.to);
    if (cmp(mFrom, mTo)) {
      var subMark = markText(doc, mFrom, mTo, marker.primary, marker.primary.type);
      marker.markers.push(subMark);
      subMark.parent = marker;
    }
  }
}

function detachSharedMarkers(markers) {
  for (var i = 0; i < markers.length; i++) {
    var marker = markers[i], linked = [marker.primary.doc];;
    linkedDocs(marker.primary.doc, function(d) { linked.push(d); });
    for (var j = 0; j < marker.markers.length; j++) {
      var subMarker = marker.markers[j];
      if (indexOf(linked, subMarker.doc) == -1) {
        subMarker.parent = null;
        marker.markers.splice(j--, 1);
      }
    }
  }
}

// TEXTMARKER SPANS

function MarkedSpan(marker, from, to) {
  this.marker = marker;
  this.from = from; this.to = to;
}

// Search an array of spans for a span matching the given marker.
function getMarkedSpanFor(spans, marker) {
  if (spans) for (var i = 0; i < spans.length; ++i) {
    var span = spans[i];
    if (span.marker == marker) return span;
  }
}
// Remove a span from an array, returning undefined if no spans are
// left (we don't store arrays for lines without spans).
function removeMarkedSpan(spans, span) {
  for (var r, i = 0; i < spans.length; ++i)
    if (spans[i] != span) (r || (r = [])).push(spans[i]);
  return r;
}
// Add a span to a line.
function addMarkedSpan(line, span) {
  line.markedSpans = line.markedSpans ? line.markedSpans.concat([span]) : [span];
  span.marker.attachLine(line);
}

// Used for the algorithm that adjusts markers for a change in the
// document. These functions cut an array of spans at a given
// character position, returning an array of remaining chunks (or
// undefined if nothing remains).
function markedSpansBefore(old, startCh, isInsert) {
  if (old) for (var i = 0, nw; i < old.length; ++i) {
    var span = old[i], marker = span.marker;
    var startsBefore = span.from == null || (marker.inclusiveLeft ? span.from <= startCh : span.from < startCh);
    if (startsBefore || span.from == startCh && marker.type == "bookmark" && (!isInsert || !span.marker.insertLeft)) {
      var endsAfter = span.to == null || (marker.inclusiveRight ? span.to >= startCh : span.to > startCh);
      (nw || (nw = [])).push(new MarkedSpan(marker, span.from, endsAfter ? null : span.to));
    }
  }
  return nw;
}
function markedSpansAfter(old, endCh, isInsert) {
  if (old) for (var i = 0, nw; i < old.length; ++i) {
    var span = old[i], marker = span.marker;
    var endsAfter = span.to == null || (marker.inclusiveRight ? span.to >= endCh : span.to > endCh);
    if (endsAfter || span.from == endCh && marker.type == "bookmark" && (!isInsert || span.marker.insertLeft)) {
      var startsBefore = span.from == null || (marker.inclusiveLeft ? span.from <= endCh : span.from < endCh);
      (nw || (nw = [])).push(new MarkedSpan(marker, startsBefore ? null : span.from - endCh,
                                            span.to == null ? null : span.to - endCh));
    }
  }
  return nw;
}

// Given a change object, compute the new set of marker spans that
// cover the line in which the change took place. Removes spans
// entirely within the change, reconnects spans belonging to the
// same marker that appear on both sides of the change, and cuts off
// spans partially within the change. Returns an array of span
// arrays with one element for each line in (after) the change.
function stretchSpansOverChange(doc, change) {
  var oldFirst = isLine(doc, change.from.line) && getLine(doc, change.from.line).markedSpans;
  var oldLast = isLine(doc, change.to.line) && getLine(doc, change.to.line).markedSpans;
  if (!oldFirst && !oldLast) return null;

  var startCh = change.from.ch, endCh = change.to.ch, isInsert = cmp(change.from, change.to) == 0;
  // Get the spans that 'stick out' on both sides
  var first = markedSpansBefore(oldFirst, startCh, isInsert);
  var last = markedSpansAfter(oldLast, endCh, isInsert);

  // Next, merge those two ends
  var sameLine = change.text.length == 1, offset = lst(change.text).length + (sameLine ? startCh : 0);
  if (first) {
    // Fix up .to properties of first
    for (var i = 0; i < first.length; ++i) {
      var span = first[i];
      if (span.to == null) {
        var found = getMarkedSpanFor(last, span.marker);
        if (!found) span.to = startCh;
        else if (sameLine) span.to = found.to == null ? null : found.to + offset;
      }
    }
  }
  if (last) {
    // Fix up .from in last (or move them into first in case of sameLine)
    for (var i = 0; i < last.length; ++i) {
      var span = last[i];
      if (span.to != null) span.to += offset;
      if (span.from == null) {
        var found = getMarkedSpanFor(first, span.marker);
        if (!found) {
          span.from = offset;
          if (sameLine) (first || (first = [])).push(span);
        }
      } else {
        span.from += offset;
        if (sameLine) (first || (first = [])).push(span);
      }
    }
  }
  // Make sure we didn't create any zero-length spans
  if (first) first = clearEmptySpans(first);
  if (last && last != first) last = clearEmptySpans(last);

  var newMarkers = [first];
  if (!sameLine) {
    // Fill gap with whole-line-spans
    var gap = change.text.length - 2, gapMarkers;
    if (gap > 0 && first)
      for (var i = 0; i < first.length; ++i)
        if (first[i].to == null)
          (gapMarkers || (gapMarkers = [])).push(new MarkedSpan(first[i].marker, null, null));
    for (var i = 0; i < gap; ++i)
      newMarkers.push(gapMarkers);
    newMarkers.push(last);
  }
  return newMarkers;
}

// Remove spans that are empty and don't have a clearWhenEmpty
// option of false.
function clearEmptySpans(spans) {
  for (var i = 0; i < spans.length; ++i) {
    var span = spans[i];
    if (span.from != null && span.from == span.to && span.marker.clearWhenEmpty !== false)
      spans.splice(i--, 1);
  }
  if (!spans.length) return null;
  return spans;
}

// Used for un/re-doing changes from the history. Combines the
// result of computing the existing spans with the set of spans that
// existed in the history (so that deleting around a span and then
// undoing brings back the span).
function mergeOldSpans(doc, change) {
  var old = getOldSpans(doc, change);
  var stretched = stretchSpansOverChange(doc, change);
  if (!old) return stretched;
  if (!stretched) return old;

  for (var i = 0; i < old.length; ++i) {
    var oldCur = old[i], stretchCur = stretched[i];
    if (oldCur && stretchCur) {
      spans: for (var j = 0; j < stretchCur.length; ++j) {
        var span = stretchCur[j];
        for (var k = 0; k < oldCur.length; ++k)
          if (oldCur[k].marker == span.marker) continue spans;
        oldCur.push(span);
      }
    } else if (stretchCur) {
      old[i] = stretchCur;
    }
  }
  return old;
}

// Used to 'clip' out readOnly ranges when making a change.
function removeReadOnlyRanges(doc, from, to) {
  var markers = null;
  doc.iter(from.line, to.line + 1, function(line) {
    if (line.markedSpans) for (var i = 0; i < line.markedSpans.length; ++i) {
      var mark = line.markedSpans[i].marker;
      if (mark.readOnly && (!markers || indexOf(markers, mark) == -1))
        (markers || (markers = [])).push(mark);
    }
  });
  if (!markers) return null;
  var parts = [{from: from, to: to}];
  for (var i = 0; i < markers.length; ++i) {
    var mk = markers[i], m = mk.find(0);
    for (var j = 0; j < parts.length; ++j) {
      var p = parts[j];
      if (cmp(p.to, m.from) < 0 || cmp(p.from, m.to) > 0) continue;
      var newParts = [j, 1], dfrom = cmp(p.from, m.from), dto = cmp(p.to, m.to);
      if (dfrom < 0 || !mk.inclusiveLeft && !dfrom)
        newParts.push({from: p.from, to: m.from});
      if (dto > 0 || !mk.inclusiveRight && !dto)
        newParts.push({from: m.to, to: p.to});
      parts.splice.apply(parts, newParts);
      j += newParts.length - 1;
    }
  }
  return parts;
}

// Connect or disconnect spans from a line.
function detachMarkedSpans(line) {
  var spans = line.markedSpans;
  if (!spans) return;
  for (var i = 0; i < spans.length; ++i)
    spans[i].marker.detachLine(line);
  line.markedSpans = null;
}
function attachMarkedSpans(line, spans) {
  if (!spans) return;
  for (var i = 0; i < spans.length; ++i)
    spans[i].marker.attachLine(line);
  line.markedSpans = spans;
}

// Helpers used when computing which overlapping collapsed span
// counts as the larger one.
function extraLeft(marker) { return marker.inclusiveLeft ? -1 : 0; }
function extraRight(marker) { return marker.inclusiveRight ? 1 : 0; }

// Returns a number indicating which of two overlapping collapsed
// spans is larger (and thus includes the other). Falls back to
// comparing ids when the spans cover exactly the same range.
function compareCollapsedMarkers(a, b) {
  var lenDiff = a.lines.length - b.lines.length;
  if (lenDiff != 0) return lenDiff;
  var aPos = a.find(), bPos = b.find();
  var fromCmp = cmp(aPos.from, bPos.from) || extraLeft(a) - extraLeft(b);
  if (fromCmp) return -fromCmp;
  var toCmp = cmp(aPos.to, bPos.to) || extraRight(a) - extraRight(b);
  if (toCmp) return toCmp;
  return b.id - a.id;
}

// Find out whether a line ends or starts in a collapsed span. If
// so, return the marker for that span.
function collapsedSpanAtSide(line, start) {
  var sps = sawCollapsedSpans && line.markedSpans, found;
  if (sps) for (var sp, i = 0; i < sps.length; ++i) {
    sp = sps[i];
    if (sp.marker.collapsed && (start ? sp.from : sp.to) == null &&
        (!found || compareCollapsedMarkers(found, sp.marker) < 0))
      found = sp.marker;
  }
  return found;
}
function collapsedSpanAtStart(line) { return collapsedSpanAtSide(line, true); }
function collapsedSpanAtEnd(line) { return collapsedSpanAtSide(line, false); }

// Test whether there exists a collapsed span that partially
// overlaps (covers the start or end, but not both) of a new span.
// Such overlap is not allowed.
function conflictingCollapsedRange(doc, lineNo, from, to, marker) {
  var line = getLine(doc, lineNo);
  var sps = sawCollapsedSpans && line.markedSpans;
  if (sps) for (var i = 0; i < sps.length; ++i) {
    var sp = sps[i];
    if (!sp.marker.collapsed) continue;
    var found = sp.marker.find(0);
    var fromCmp = cmp(found.from, from) || extraLeft(sp.marker) - extraLeft(marker);
    var toCmp = cmp(found.to, to) || extraRight(sp.marker) - extraRight(marker);
    if (fromCmp >= 0 && toCmp <= 0 || fromCmp <= 0 && toCmp >= 0) continue;
    if (fromCmp <= 0 && (cmp(found.to, from) > 0 || (sp.marker.inclusiveRight && marker.inclusiveLeft)) ||
        fromCmp >= 0 && (cmp(found.from, to) < 0 || (sp.marker.inclusiveLeft && marker.inclusiveRight)))
      return true;
  }
}

// A visual line is a line as drawn on the screen. Folding, for
// example, can cause multiple logical lines to appear on the same
// visual line. This finds the start of the visual line that the
// given line is part of (usually that is the line itself).
function visualLine(line) {
  var merged;
  while (merged = collapsedSpanAtStart(line))
    line = merged.find(-1, true).line;
  return line;
}

// Returns an array of logical lines that continue the visual line
// started by the argument, or undefined if there are no such lines.
function visualLineContinued(line) {
  var merged, lines;
  while (merged = collapsedSpanAtEnd(line)) {
    line = merged.find(1, true).line;
    (lines || (lines = [])).push(line);
  }
  return lines;
}

// Get the line number of the start of the visual line that the
// given line number is part of.
function visualLineNo(doc, lineN) {
  var line = getLine(doc, lineN), vis = visualLine(line);
  if (line == vis) return lineN;
  return lineNo(vis);
}
// Get the line number of the start of the next visual line after
// the given line.
function visualLineEndNo(doc, lineN) {
  if (lineN > doc.lastLine()) return lineN;
  var line = getLine(doc, lineN), merged;
  if (!lineIsHidden(doc, line)) return lineN;
  while (merged = collapsedSpanAtEnd(line))
    line = merged.find(1, true).line;
  return lineNo(line) + 1;
}

// Compute whether a line is hidden. Lines count as hidden when they
// are part of a visual line that starts with another line, or when
// they are entirely covered by collapsed, non-widget span.
function lineIsHidden(doc, line) {
  var sps = sawCollapsedSpans && line.markedSpans;
  if (sps) for (var sp, i = 0; i < sps.length; ++i) {
    sp = sps[i];
    if (!sp.marker.collapsed) continue;
    if (sp.from == null) return true;
    if (sp.marker.widgetNode) continue;
    if (sp.from == 0 && sp.marker.inclusiveLeft && lineIsHiddenInner(doc, line, sp))
      return true;
  }
}
function lineIsHiddenInner(doc, line, span) {
  if (span.to == null) {
    var end = span.marker.find(1, true);
    return lineIsHiddenInner(doc, end.line, getMarkedSpanFor(end.line.markedSpans, span.marker));
  }
  if (span.marker.inclusiveRight && span.to == line.text.length)
    return true;
  for (var sp, i = 0; i < line.markedSpans.length; ++i) {
    sp = line.markedSpans[i];
    if (sp.marker.collapsed && !sp.marker.widgetNode && sp.from == span.to &&
        (sp.to == null || sp.to != span.from) &&
        (sp.marker.inclusiveLeft || span.marker.inclusiveRight) &&
        lineIsHiddenInner(doc, line, sp)) return true;
  }
}

// LINE WIDGETS

// Line widgets are block elements displayed above or below a line.

var LineWidget = CodeMirror.LineWidget = function(cm, node, options) {
  if (options) for (var opt in options) if (options.hasOwnProperty(opt))
    this[opt] = options[opt];
  this.cm = cm;
  this.node = node;
};
eventMixin(LineWidget);

function adjustScrollWhenAboveVisible(cm, line, diff) {
  if (heightAtLine(line) < ((cm.curOp && cm.curOp.scrollTop) || cm.doc.scrollTop))
    addToScrollPos(cm, null, diff);
}

LineWidget.prototype.clear = function() {
  var cm = this.cm, ws = this.line.widgets, line = this.line, no = lineNo(line);
  if (no == null || !ws) return;
  for (var i = 0; i < ws.length; ++i) if (ws[i] == this) ws.splice(i--, 1);
  if (!ws.length) line.widgets = null;
  var height = widgetHeight(this);
  runInOp(cm, function() {
    adjustScrollWhenAboveVisible(cm, line, -height);
    regLineChange(cm, no, "widget");
    updateLineHeight(line, Math.max(0, line.height - height));
  });
};
LineWidget.prototype.changed = function() {
  var oldH = this.height, cm = this.cm, line = this.line;
  this.height = null;
  var diff = widgetHeight(this) - oldH;
  if (!diff) return;
  runInOp(cm, function() {
    cm.curOp.forceUpdate = true;
    adjustScrollWhenAboveVisible(cm, line, diff);
    updateLineHeight(line, line.height + diff);
  });
};

function widgetHeight(widget) {
  if (widget.height != null) return widget.height;
  if (!contains(document.body, widget.node)) {
    var parentStyle = "position: relative;";
    if (widget.coverGutter)
      parentStyle += "margin-left: -" + widget.cm.getGutterElement().offsetWidth + "px;";
    removeChildrenAndAdd(widget.cm.display.measure, elt("div", [widget.node], null, parentStyle));
  }
  return widget.height = widget.node.offsetHeight;
}

function addLineWidget(cm, handle, node, options) {
  var widget = new LineWidget(cm, node, options);
  if (widget.noHScroll) cm.display.alignWidgets = true;
  changeLine(cm.doc, handle, "widget", function(line) {
    var widgets = line.widgets || (line.widgets = []);
    if (widget.insertAt == null) widgets.push(widget);
    else widgets.splice(Math.min(widgets.length - 1, Math.max(0, widget.insertAt)), 0, widget);
    widget.line = line;
    if (!lineIsHidden(cm.doc, line)) {
      var aboveVisible = heightAtLine(line) < cm.doc.scrollTop;
      updateLineHeight(line, line.height + widgetHeight(widget));
      if (aboveVisible) addToScrollPos(cm, null, widget.height);
      cm.curOp.forceUpdate = true;
    }
    return true;
  });
  return widget;
}

// LINE DATA STRUCTURE

// Line objects. These hold state related to a line, including
// highlighting info (the styles array).
var Line = CodeMirror.Line = function(text, markedSpans, estimateHeight) {
  this.text = text;
  attachMarkedSpans(this, markedSpans);
  this.height = estimateHeight ? estimateHeight(this) : 1;
};
eventMixin(Line);
Line.prototype.lineNo = function() { return lineNo(this); };

// Change the content (text, markers) of a line. Automatically
// invalidates cached information and tries to re-estimate the
// line's height.
function updateLine(line, text, markedSpans, estimateHeight) {
  line.text = text;
  if (line.stateAfter) line.stateAfter = null;
  if (line.styles) line.styles = null;
  if (line.order != null) line.order = null;
  detachMarkedSpans(line);
  attachMarkedSpans(line, markedSpans);
  var estHeight = estimateHeight ? estimateHeight(line) : 1;
  if (estHeight != line.height) updateLineHeight(line, estHeight);
}

// Detach a line from the document tree and its markers.
function cleanUpLine(line) {
  line.parent = null;
  detachMarkedSpans(line);
}

function extractLineClasses(type, output) {
  if (type) for (;;) {
    var lineClass = type.match(/(?:^|\s+)line-(background-)?(\S+)/);
    if (!lineClass) break;
    type = type.slice(0, lineClass.index) + type.slice(lineClass.index + lineClass[0].length);
    var prop = lineClass[1] ? "bgClass" : "textClass";
    if (output[prop] == null)
      output[prop] = lineClass[2];
    else if (!(new RegExp("(?:^|\s)" + lineClass[2] + "(?:$|\s)")).test(output[prop]))
      output[prop] += " " + lineClass[2];
  }
  return type;
}

function callBlankLine(mode, state) {
  if (mode.blankLine) return mode.blankLine(state);
  if (!mode.innerMode) return;
  var inner = CodeMirror.innerMode(mode, state);
  if (inner.mode.blankLine) return inner.mode.blankLine(inner.state);
}

function readToken(mode, stream, state) {
  for (var i = 0; i < 10; i++) {
    var style = mode.token(stream, state);
    if (stream.pos > stream.start) return style;
  }
  throw new Error("Mode " + mode.name + " failed to advance stream.");
}

// Run the given mode's parser over a line, calling f for each token.
function runMode(cm, text, mode, state, f, lineClasses, forceToEnd) {
  var flattenSpans = mode.flattenSpans;
  if (flattenSpans == null) flattenSpans = cm.options.flattenSpans;
  var curStart = 0, curStyle = null;
  var stream = new StringStream(text, cm.options.tabSize), style;
  if (text == "") extractLineClasses(callBlankLine(mode, state), lineClasses);
  while (!stream.eol()) {
    if (stream.pos > cm.options.maxHighlightLength) {
      flattenSpans = false;
      if (forceToEnd) processLine(cm, text, state, stream.pos);
      stream.pos = text.length;
      style = null;
    } else {
      style = extractLineClasses(readToken(mode, stream, state), lineClasses);
    }
    if (cm.options.addModeClass) {
      var mName = CodeMirror.innerMode(mode, state).mode.name;
      if (mName) style = "m-" + (style ? mName + " " + style : mName);
    }
    if (!flattenSpans || curStyle != style) {
      if (curStart < stream.start) f(stream.start, curStyle);
      curStart = stream.start; curStyle = style;
    }
    stream.start = stream.pos;
  }
  while (curStart < stream.pos) {
    // Webkit seems to refuse to render text nodes longer than 57444 characters
    var pos = Math.min(stream.pos, curStart + 50000);
    f(pos, curStyle);
    curStart = pos;
  }
}

// Compute a style array (an array starting with a mode generation
// -- for invalidation -- followed by pairs of end positions and
// style strings), which is used to highlight the tokens on the
// line.
function highlightLine(cm, line, state, forceToEnd) {
  // A styles array always starts with a number identifying the
  // mode/overlays that it is based on (for easy invalidation).
  var st = [cm.state.modeGen], lineClasses = {};
  // Compute the base array of styles
  runMode(cm, line.text, cm.doc.mode, state, function(end, style) {
    st.push(end, style);
  }, lineClasses, forceToEnd);

  // Run overlays, adjust style array.
  for (var o = 0; o < cm.state.overlays.length; ++o) {
    var overlay = cm.state.overlays[o], i = 1, at = 0;
    runMode(cm, line.text, overlay.mode, true, function(end, style) {
      var start = i;
      // Ensure there's a token end at the current position, and that i points at it
      while (at < end) {
        var i_end = st[i];
        if (i_end > end)
          st.splice(i, 1, end, st[i+1], i_end);
        i += 2;
        at = Math.min(end, i_end);
      }
      if (!style) return;
      if (overlay.opaque) {
        st.splice(start, i - start, end, "cm-overlay " + style);
        i = start + 2;
      } else {
        for (; start < i; start += 2) {
          var cur = st[start+1];
          st[start+1] = (cur ? cur + " " : "") + "cm-overlay " + style;
        }
      }
    }, lineClasses);
  }

  return {styles: st, classes: lineClasses.bgClass || lineClasses.textClass ? lineClasses : null};
}

function getLineStyles(cm, line) {
  if (!line.styles || line.styles[0] != cm.state.modeGen) {
    var result = highlightLine(cm, line, line.stateAfter = getStateBefore(cm, lineNo(line)));
    line.styles = result.styles;
    if (result.classes) line.styleClasses = result.classes;
    else if (line.styleClasses) line.styleClasses = null;
  }
  return line.styles;
}

// Lightweight form of highlight -- proceed over this line and
// update state, but don't save a style array. Used for lines that
// aren't currently visible.
function processLine(cm, text, state, startAt) {
  var mode = cm.doc.mode;
  var stream = new StringStream(text, cm.options.tabSize);
  stream.start = stream.pos = startAt || 0;
  if (text == "") callBlankLine(mode, state);
  while (!stream.eol() && stream.pos <= cm.options.maxHighlightLength) {
    readToken(mode, stream, state);
    stream.start = stream.pos;
  }
}

// Convert a style as returned by a mode (either null, or a string
// containing one or more styles) to a CSS style. This is cached,
// and also looks for line-wide styles.
var styleToClassCache = {}, styleToClassCacheWithMode = {};
function interpretTokenStyle(style, options) {
  if (!style || /^\s*$/.test(style)) return null;
  var cache = options.addModeClass ? styleToClassCacheWithMode : styleToClassCache;
  return cache[style] ||
    (cache[style] = style.replace(/\S+/g, "cm-$&"));
}

// Render the DOM representation of the text of a line. Also builds
// up a 'line map', which points at the DOM nodes that represent
// specific stretches of text, and is used by the measuring code.
// The returned object contains the DOM node, this map, and
// information about line-wide styles that were set by the mode.
function buildLineContent(cm, lineView) {
  // The padding-right forces the element to have a 'border', which
  // is needed on Webkit to be able to get line-level bounding
  // rectangles for it (in measureChar).
  var content = elt("span", null, null, webkit ? "padding-right: .1px" : null);
  var builder = {pre: elt("pre", [content]), content: content, col: 0, pos: 0, cm: cm};
  lineView.measure = {};

  // Iterate over the logical lines that make up this visual line.
  for (var i = 0; i <= (lineView.rest ? lineView.rest.length : 0); i++) {
    var line = i ? lineView.rest[i - 1] : lineView.line, order;
    builder.pos = 0;
    builder.addToken = buildToken;
    // Optionally wire in some hacks into the token-rendering
    // algorithm, to deal with browser quirks.
    if ((ie || webkit) && cm.getOption("lineWrapping"))
      builder.addToken = buildTokenSplitSpaces(builder.addToken);
    if (hasBadBidiRects(cm.display.measure) && (order = getOrder(line)))
      builder.addToken = buildTokenBadBidi(builder.addToken, order);
    builder.map = [];
    insertLineContent(line, builder, getLineStyles(cm, line));
    if (line.styleClasses) {
      if (line.styleClasses.bgClass)
        builder.bgClass = joinClasses(line.styleClasses.bgClass, builder.bgClass || "");
      if (line.styleClasses.textClass)
        builder.textClass = joinClasses(line.styleClasses.textClass, builder.textClass || "");
    }

    // Ensure at least a single node is present, for measuring.
    if (builder.map.length == 0)
      builder.map.push(0, 0, builder.content.appendChild(zeroWidthElement(cm.display.measure)));

    // Store the map and a cache object for the current logical line
    if (i == 0) {
      lineView.measure.map = builder.map;
      lineView.measure.cache = {};
    } else {
      (lineView.measure.maps || (lineView.measure.maps = [])).push(builder.map);
      (lineView.measure.caches || (lineView.measure.caches = [])).push({});
    }
  }

  signal(cm, "renderLine", cm, lineView.line, builder.pre);
  if (builder.pre.className)
    builder.textClass = joinClasses(builder.pre.className, builder.textClass || "");
  return builder;
}

function defaultSpecialCharPlaceholder(ch) {
  var token = elt("span", "\u2022", "cm-invalidchar");
  token.title = "\\u" + ch.charCodeAt(0).toString(16);
  return token;
}

// Build up the DOM representation for a single token, and add it to
// the line map. Takes care to render special characters separately.
function buildToken(builder, text, style, startStyle, endStyle, title) {
  if (!text) return;
  var special = builder.cm.options.specialChars, mustWrap = false;
  if (!special.test(text)) {
    builder.col += text.length;
    var content = document.createTextNode(text);
    builder.map.push(builder.pos, builder.pos + text.length, content);
    if (ie && ie_version < 9) mustWrap = true;
    builder.pos += text.length;
  } else {
    var content = document.createDocumentFragment(), pos = 0;
    while (true) {
      special.lastIndex = pos;
      var m = special.exec(text);
      var skipped = m ? m.index - pos : text.length - pos;
      if (skipped) {
        var txt = document.createTextNode(text.slice(pos, pos + skipped));
        if (ie && ie_version < 9) content.appendChild(elt("span", [txt]));
        else content.appendChild(txt);
        builder.map.push(builder.pos, builder.pos + skipped, txt);
        builder.col += skipped;
        builder.pos += skipped;
      }
      if (!m) break;
      pos += skipped + 1;
      if (m[0] == "\t") {
        var tabSize = builder.cm.options.tabSize, tabWidth = tabSize - builder.col % tabSize;
        var txt = content.appendChild(elt("span", spaceStr(tabWidth), "cm-tab"));
        builder.col += tabWidth;
      } else {
        var txt = builder.cm.options.specialCharPlaceholder(m[0]);
        if (ie && ie_version < 9) content.appendChild(elt("span", [txt]));
        else content.appendChild(txt);
        builder.col += 1;
      }
      builder.map.push(builder.pos, builder.pos + 1, txt);
      builder.pos++;
    }
  }
  if (style || startStyle || endStyle || mustWrap) {
    var fullStyle = style || "";
    if (startStyle) fullStyle += startStyle;
    if (endStyle) fullStyle += endStyle;
    var token = elt("span", [content], fullStyle);
    if (title) token.title = title;
    return builder.content.appendChild(token);
  }
  builder.content.appendChild(content);
}

function buildTokenSplitSpaces(inner) {
  function split(old) {
    var out = " ";
    for (var i = 0; i < old.length - 2; ++i) out += i % 2 ? " " : "\u00a0";
    out += " ";
    return out;
  }
  return function(builder, text, style, startStyle, endStyle, title) {
    inner(builder, text.replace(/ {3,}/g, split), style, startStyle, endStyle, title);
  };
}

// Work around nonsense dimensions being reported for stretches of
// right-to-left text.
function buildTokenBadBidi(inner, order) {
  return function(builder, text, style, startStyle, endStyle, title) {
    style = style ? style + " cm-force-border" : "cm-force-border";
    var start = builder.pos, end = start + text.length;
    for (;;) {
      // Find the part that overlaps with the start of this text
      for (var i = 0; i < order.length; i++) {
        var part = order[i];
        if (part.to > start && part.from <= start) break;
      }
      if (part.to >= end) return inner(builder, text, style, startStyle, endStyle, title);
      inner(builder, text.slice(0, part.to - start), style, startStyle, null, title);
      startStyle = null;
      text = text.slice(part.to - start);
      start = part.to;
    }
  };
}

function buildCollapsedSpan(builder, size, marker, ignoreWidget) {
  var widget = !ignoreWidget && marker.widgetNode;
  if (widget) {
    builder.map.push(builder.pos, builder.pos + size, widget);
    builder.content.appendChild(widget);
  }
  builder.pos += size;
}

// Outputs a number of spans to make up a line, taking highlighting
// and marked text into account.
function insertLineContent(line, builder, styles) {
  var spans = line.markedSpans, allText = line.text, at = 0;
  if (!spans) {
    for (var i = 1; i < styles.length; i+=2)
      builder.addToken(builder, allText.slice(at, at = styles[i]), interpretTokenStyle(styles[i+1], builder.cm.options));
    return;
  }

  var len = allText.length, pos = 0, i = 1, text = "", style;
  var nextChange = 0, spanStyle, spanEndStyle, spanStartStyle, title, collapsed;
  for (;;) {
    if (nextChange == pos) { // Update current marker set
      spanStyle = spanEndStyle = spanStartStyle = title = "";
      collapsed = null; nextChange = Infinity;
      var foundBookmarks = [];
      for (var j = 0; j < spans.length; ++j) {
        var sp = spans[j], m = sp.marker;
        if (sp.from <= pos && (sp.to == null || sp.to > pos)) {
          if (sp.to != null && nextChange > sp.to) { nextChange = sp.to; spanEndStyle = ""; }
          if (m.className) spanStyle += " " + m.className;
          if (m.startStyle && sp.from == pos) spanStartStyle += " " + m.startStyle;
          if (m.endStyle && sp.to == nextChange) spanEndStyle += " " + m.endStyle;
          if (m.title && !title) title = m.title;
          if (m.collapsed && (!collapsed || compareCollapsedMarkers(collapsed.marker, m) < 0))
            collapsed = sp;
        } else if (sp.from > pos && nextChange > sp.from) {
          nextChange = sp.from;
        }
        if (m.type == "bookmark" && sp.from == pos && m.widgetNode) foundBookmarks.push(m);
      }
      if (collapsed && (collapsed.from || 0) == pos) {
        buildCollapsedSpan(builder, (collapsed.to == null ? len + 1 : collapsed.to) - pos,
                           collapsed.marker, collapsed.from == null);
        if (collapsed.to == null) return;
      }
      if (!collapsed && foundBookmarks.length) for (var j = 0; j < foundBookmarks.length; ++j)
        buildCollapsedSpan(builder, 0, foundBookmarks[j]);
    }
    if (pos >= len) break;

    var upto = Math.min(len, nextChange);
    while (true) {
      if (text) {
        var end = pos + text.length;
        if (!collapsed) {
          var tokenText = end > upto ? text.slice(0, upto - pos) : text;
          builder.addToken(builder, tokenText, style ? style + spanStyle : spanStyle,
                           spanStartStyle, pos + tokenText.length == nextChange ? spanEndStyle : "", title);
        }
        if (end >= upto) {text = text.slice(upto - pos); pos = upto; break;}
        pos = end;
        spanStartStyle = "";
      }
      text = allText.slice(at, at = styles[i++]);
      style = interpretTokenStyle(styles[i++], builder.cm.options);
    }
  }
}

// DOCUMENT DATA STRUCTURE

// By default, updates that start and end at the beginning of a line
// are treated specially, in order to make the association of line
// widgets and marker elements with the text behave more intuitive.
function isWholeLineUpdate(doc, change) {
  return change.from.ch == 0 && change.to.ch == 0 && lst(change.text) == "" &&
    (!doc.cm || doc.cm.options.wholeLineUpdateBefore);
}

// Perform a change on the document data structure.
function updateDoc(doc, change, markedSpans, estimateHeight) {
  function spansFor(n) {return markedSpans ? markedSpans[n] : null;}
  function update(line, text, spans) {
    updateLine(line, text, spans, estimateHeight);
    signalLater(line, "change", line, change);
  }

  var from = change.from, to = change.to, text = change.text;
  var firstLine = getLine(doc, from.line), lastLine = getLine(doc, to.line);
  var lastText = lst(text), lastSpans = spansFor(text.length - 1), nlines = to.line - from.line;

  // Adjust the line structure
  if (isWholeLineUpdate(doc, change)) {
    // This is a whole-line replace. Treated specially to make
    // sure line objects move the way they are supposed to.
    for (var i = 0, added = []; i < text.length - 1; ++i)
      added.push(new Line(text[i], spansFor(i), estimateHeight));
    update(lastLine, lastLine.text, lastSpans);
    if (nlines) doc.remove(from.line, nlines);
    if (added.length) doc.insert(from.line, added);
  } else if (firstLine == lastLine) {
    if (text.length == 1) {
      update(firstLine, firstLine.text.slice(0, from.ch) + lastText + firstLine.text.slice(to.ch), lastSpans);
    } else {
      for (var added = [], i = 1; i < text.length - 1; ++i)
        added.push(new Line(text[i], spansFor(i), estimateHeight));
      added.push(new Line(lastText + firstLine.text.slice(to.ch), lastSpans, estimateHeight));
      update(firstLine, firstLine.text.slice(0, from.ch) + text[0], spansFor(0));
      doc.insert(from.line + 1, added);
    }
  } else if (text.length == 1) {
    update(firstLine, firstLine.text.slice(0, from.ch) + text[0] + lastLine.text.slice(to.ch), spansFor(0));
    doc.remove(from.line + 1, nlines);
  } else {
    update(firstLine, firstLine.text.slice(0, from.ch) + text[0], spansFor(0));
    update(lastLine, lastText + lastLine.text.slice(to.ch), lastSpans);
    for (var i = 1, added = []; i < text.length - 1; ++i)
      added.push(new Line(text[i], spansFor(i), estimateHeight));
    if (nlines > 1) doc.remove(from.line + 1, nlines - 1);
    doc.insert(from.line + 1, added);
  }

  signalLater(doc, "change", doc, change);
}

// The document is represented as a BTree consisting of leaves, with
// chunk of lines in them, and branches, with up to ten leaves or
// other branch nodes below them. The top node is always a branch
// node, and is the document object itself (meaning it has
// additional methods and properties).
//
// All nodes have parent links. The tree is used both to go from
// line numbers to line objects, and to go from objects to numbers.
// It also indexes by height, and is used to convert between height
// and line object, and to find the total height of the document.
//
// See also http://marijnhaverbeke.nl/blog/codemirror-line-tree.html

function LeafChunk(lines) {
  this.lines = lines;
  this.parent = null;
  for (var i = 0, height = 0; i < lines.length; ++i) {
    lines[i].parent = this;
    height += lines[i].height;
  }
  this.height = height;
}

LeafChunk.prototype = {
  chunkSize: function() { return this.lines.length; },
  // Remove the n lines at offset 'at'.
  removeInner: function(at, n) {
    for (var i = at, e = at + n; i < e; ++i) {
      var line = this.lines[i];
      this.height -= line.height;
      cleanUpLine(line);
      signalLater(line, "delete");
    }
    this.lines.splice(at, n);
  },
  // Helper used to collapse a small branch into a single leaf.
  collapse: function(lines) {
    lines.push.apply(lines, this.lines);
  },
  // Insert the given array of lines at offset 'at', count them as
  // having the given height.
  insertInner: function(at, lines, height) {
    this.height += height;
    this.lines = this.lines.slice(0, at).concat(lines).concat(this.lines.slice(at));
    for (var i = 0; i < lines.length; ++i) lines[i].parent = this;
  },
  // Used to iterate over a part of the tree.
  iterN: function(at, n, op) {
    for (var e = at + n; at < e; ++at)
      if (op(this.lines[at])) return true;
  }
};

function BranchChunk(children) {
  this.children = children;
  var size = 0, height = 0;
  for (var i = 0; i < children.length; ++i) {
    var ch = children[i];
    size += ch.chunkSize(); height += ch.height;
    ch.parent = this;
  }
  this.size = size;
  this.height = height;
  this.parent = null;
}

BranchChunk.prototype = {
  chunkSize: function() { return this.size; },
  removeInner: function(at, n) {
    this.size -= n;
    for (var i = 0; i < this.children.length; ++i) {
      var child = this.children[i], sz = child.chunkSize();
      if (at < sz) {
        var rm = Math.min(n, sz - at), oldHeight = child.height;
        child.removeInner(at, rm);
        this.height -= oldHeight - child.height;
        if (sz == rm) { this.children.splice(i--, 1); child.parent = null; }
        if ((n -= rm) == 0) break;
        at = 0;
      } else at -= sz;
    }
    // If the result is smaller than 25 lines, ensure that it is a
    // single leaf node.
    if (this.size - n < 25 &&
        (this.children.length > 1 || !(this.children[0] instanceof LeafChunk))) {
      var lines = [];
      this.collapse(lines);
      this.children = [new LeafChunk(lines)];
      this.children[0].parent = this;
    }
  },
  collapse: function(lines) {
    for (var i = 0; i < this.children.length; ++i) this.children[i].collapse(lines);
  },
  insertInner: function(at, lines, height) {
    this.size += lines.length;
    this.height += height;
    for (var i = 0; i < this.children.length; ++i) {
      var child = this.children[i], sz = child.chunkSize();
      if (at <= sz) {
        child.insertInner(at, lines, height);
        if (child.lines && child.lines.length > 50) {
          while (child.lines.length > 50) {
            var spilled = child.lines.splice(child.lines.length - 25, 25);
            var newleaf = new LeafChunk(spilled);
            child.height -= newleaf.height;
            this.children.splice(i + 1, 0, newleaf);
            newleaf.parent = this;
          }
          this.maybeSpill();
        }
        break;
      }
      at -= sz;
    }
  },
  // When a node has grown, check whether it should be split.
  maybeSpill: function() {
    if (this.children.length <= 10) return;
    var me = this;
    do {
      var spilled = me.children.splice(me.children.length - 5, 5);
      var sibling = new BranchChunk(spilled);
      if (!me.parent) { // Become the parent node
        var copy = new BranchChunk(me.children);
        copy.parent = me;
        me.children = [copy, sibling];
        me = copy;
      } else {
        me.size -= sibling.size;
        me.height -= sibling.height;
        var myIndex = indexOf(me.parent.children, me);
        me.parent.children.splice(myIndex + 1, 0, sibling);
      }
      sibling.parent = me.parent;
    } while (me.children.length > 10);
    me.parent.maybeSpill();
  },
  iterN: function(at, n, op) {
    for (var i = 0; i < this.children.length; ++i) {
      var child = this.children[i], sz = child.chunkSize();
      if (at < sz) {
        var used = Math.min(n, sz - at);
        if (child.iterN(at, used, op)) return true;
        if ((n -= used) == 0) break;
        at = 0;
      } else at -= sz;
    }
  }
};

var nextDocId = 0;
var Doc = CodeMirror.Doc = function(text, mode, firstLine) {
  if (!(this instanceof Doc)) return new Doc(text, mode, firstLine);
  if (firstLine == null) firstLine = 0;

  BranchChunk.call(this, [new LeafChunk([new Line("", null)])]);
  this.first = firstLine;
  this.scrollTop = this.scrollLeft = 0;
  this.cantEdit = false;
  this.cleanGeneration = 1;
  this.frontier = firstLine;
  var start = Pos(firstLine, 0);
  this.sel = simpleSelection(start);
  this.history = new History(null);
  this.id = ++nextDocId;
  this.modeOption = mode;

  if (typeof text == "string") text = splitLines(text);
  updateDoc(this, {from: start, to: start, text: text});
  setSelection(this, simpleSelection(start), sel_dontScroll);
};

Doc.prototype = createObj(BranchChunk.prototype, {
  constructor: Doc,
  // Iterate over the document. Supports two forms -- with only one
  // argument, it calls that for each line in the document. With
  // three, it iterates over the range given by the first two (with
  // the second being non-inclusive).
  iter: function(from, to, op) {
    if (op) this.iterN(from - this.first, to - from, op);
    else this.iterN(this.first, this.first + this.size, from);
  },

  // Non-public interface for adding and removing lines.
  insert: function(at, lines) {
    var height = 0;
    for (var i = 0; i < lines.length; ++i) height += lines[i].height;
    this.insertInner(at - this.first, lines, height);
  },
  remove: function(at, n) { this.removeInner(at - this.first, n); },

  // From here, the methods are part of the public interface. Most
  // are also available from CodeMirror (editor) instances.

  getValue: function(lineSep) {
    var lines = getLines(this, this.first, this.first + this.size);
    if (lineSep === false) return lines;
    return lines.join(lineSep || "\n");
  },
  setValue: docMethodOp(function(code) {
    var top = Pos(this.first, 0), last = this.first + this.size - 1;
    makeChange(this, {from: top, to: Pos(last, getLine(this, last).text.length),
                      text: splitLines(code), origin: "setValue"}, true);
    setSelection(this, simpleSelection(top));
  }),
  replaceRange: function(code, from, to, origin) {
    from = clipPos(this, from);
    to = to ? clipPos(this, to) : from;
    replaceRange(this, code, from, to, origin);
  },
  getRange: function(from, to, lineSep) {
    var lines = getBetween(this, clipPos(this, from), clipPos(this, to));
    if (lineSep === false) return lines;
    return lines.join(lineSep || "\n");
  },

  getLine: function(line) {var l = this.getLineHandle(line); return l && l.text;},

  getLineHandle: function(line) {if (isLine(this, line)) return getLine(this, line);},
  getLineNumber: function(line) {return lineNo(line);},

  getLineHandleVisualStart: function(line) {
    if (typeof line == "number") line = getLine(this, line);
    return visualLine(line);
  },

  lineCount: function() {return this.size;},
  firstLine: function() {return this.first;},
  lastLine: function() {return this.first + this.size - 1;},

  clipPos: function(pos) {return clipPos(this, pos);},

  getCursor: function(start) {
    var range = this.sel.primary(), pos;
    if (start == null || start == "head") pos = range.head;
    else if (start == "anchor") pos = range.anchor;
    else if (start == "end" || start == "to" || start === false) pos = range.to();
    else pos = range.from();
    return pos;
  },
  listSelections: function() { return this.sel.ranges; },
  somethingSelected: function() {return this.sel.somethingSelected();},

  setCursor: docMethodOp(function(line, ch, options) {
    setSimpleSelection(this, clipPos(this, typeof line == "number" ? Pos(line, ch || 0) : line), null, options);
  }),
  setSelection: docMethodOp(function(anchor, head, options) {
    setSimpleSelection(this, clipPos(this, anchor), clipPos(this, head || anchor), options);
  }),
  extendSelection: docMethodOp(function(head, other, options) {
    extendSelection(this, clipPos(this, head), other && clipPos(this, other), options);
  }),
  extendSelections: docMethodOp(function(heads, options) {
    extendSelections(this, clipPosArray(this, heads, options));
  }),
  extendSelectionsBy: docMethodOp(function(f, options) {
    extendSelections(this, map(this.sel.ranges, f), options);
  }),
  setSelections: docMethodOp(function(ranges, primary, options) {
    if (!ranges.length) return;
    for (var i = 0, out = []; i < ranges.length; i++)
      out[i] = new Range(clipPos(this, ranges[i].anchor),
                         clipPos(this, ranges[i].head));
    if (primary == null) primary = Math.min(ranges.length - 1, this.sel.primIndex);
    setSelection(this, normalizeSelection(out, primary), options);
  }),
  addSelection: docMethodOp(function(anchor, head, options) {
    var ranges = this.sel.ranges.slice(0);
    ranges.push(new Range(clipPos(this, anchor), clipPos(this, head || anchor)));
    setSelection(this, normalizeSelection(ranges, ranges.length - 1), options);
  }),

  getSelection: function(lineSep) {
    var ranges = this.sel.ranges, lines;
    for (var i = 0; i < ranges.length; i++) {
      var sel = getBetween(this, ranges[i].from(), ranges[i].to());
      lines = lines ? lines.concat(sel) : sel;
    }
    if (lineSep === false) return lines;
    else return lines.join(lineSep || "\n");
  },
  getSelections: function(lineSep) {
    var parts = [], ranges = this.sel.ranges;
    for (var i = 0; i < ranges.length; i++) {
      var sel = getBetween(this, ranges[i].from(), ranges[i].to());
      if (lineSep !== false) sel = sel.join(lineSep || "\n");
      parts[i] = sel;
    }
    return parts;
  },
  replaceSelection: function(code, collapse, origin) {
    var dup = [];
    for (var i = 0; i < this.sel.ranges.length; i++)
      dup[i] = code;
    this.replaceSelections(dup, collapse, origin || "+input");
  },
  replaceSelections: docMethodOp(function(code, collapse, origin) {
    var changes = [], sel = this.sel;
    for (var i = 0; i < sel.ranges.length; i++) {
      var range = sel.ranges[i];
      changes[i] = {from: range.from(), to: range.to(), text: splitLines(code[i]), origin: origin};
    }
    var newSel = collapse && collapse != "end" && computeReplacedSel(this, changes, collapse);
    for (var i = changes.length - 1; i >= 0; i--)
      makeChange(this, changes[i]);
    if (newSel) setSelectionReplaceHistory(this, newSel);
    else if (this.cm) ensureCursorVisible(this.cm);
  }),
  undo: docMethodOp(function() {makeChangeFromHistory(this, "undo");}),
  redo: docMethodOp(function() {makeChangeFromHistory(this, "redo");}),
  undoSelection: docMethodOp(function() {makeChangeFromHistory(this, "undo", true);}),
  redoSelection: docMethodOp(function() {makeChangeFromHistory(this, "redo", true);}),

  setExtending: function(val) {this.extend = val;},
  getExtending: function() {return this.extend;},

  historySize: function() {
    var hist = this.history, done = 0, undone = 0;
    for (var i = 0; i < hist.done.length; i++) if (!hist.done[i].ranges) ++done;
    for (var i = 0; i < hist.undone.length; i++) if (!hist.undone[i].ranges) ++undone;
    return {undo: done, redo: undone};
  },
  clearHistory: function() {this.history = new History(this.history.maxGeneration);},

  markClean: function() {
    this.cleanGeneration = this.changeGeneration(true);
  },
  changeGeneration: function(forceSplit) {
    if (forceSplit)
      this.history.lastOp = this.history.lastSelOp = this.history.lastOrigin = null;
    return this.history.generation;
  },
  isClean: function (gen) {
    return this.history.generation == (gen || this.cleanGeneration);
  },

  getHistory: function() {
    return {done: copyHistoryArray(this.history.done),
            undone: copyHistoryArray(this.history.undone)};
  },
  setHistory: function(histData) {
    var hist = this.history = new History(this.history.maxGeneration);
    hist.done = copyHistoryArray(histData.done.slice(0), null, true);
    hist.undone = copyHistoryArray(histData.undone.slice(0), null, true);
  },

  addLineClass: docMethodOp(function(handle, where, cls) {
    return changeLine(this, handle, "class", function(line) {
      var prop = where == "text" ? "textClass" : where == "background" ? "bgClass" : "wrapClass";
      if (!line[prop]) line[prop] = cls;
      else if (new RegExp("(?:^|\\s)" + cls + "(?:$|\\s)").test(line[prop])) return false;
      else line[prop] += " " + cls;
      return true;
    });
  }),
  removeLineClass: docMethodOp(function(handle, where, cls) {
    return changeLine(this, handle, "class", function(line) {
      var prop = where == "text" ? "textClass" : where == "background" ? "bgClass" : "wrapClass";
      var cur = line[prop];
      if (!cur) return false;
      else if (cls == null) line[prop] = null;
      else {
        var found = cur.match(new RegExp("(?:^|\\s+)" + cls + "(?:$|\\s+)"));
        if (!found) return false;
        var end = found.index + found[0].length;
        line[prop] = cur.slice(0, found.index) + (!found.index || end == cur.length ? "" : " ") + cur.slice(end) || null;
      }
      return true;
    });
  }),

  markText: function(from, to, options) {
    return markText(this, clipPos(this, from), clipPos(this, to), options, "range");
  },
  setBookmark: function(pos, options) {
    var realOpts = {replacedWith: options && (options.nodeType == null ? options.widget : options),
                    insertLeft: options && options.insertLeft,
                    clearWhenEmpty: false, shared: options && options.shared};
    pos = clipPos(this, pos);
    return markText(this, pos, pos, realOpts, "bookmark");
  },
  findMarksAt: function(pos) {
    pos = clipPos(this, pos);
    var markers = [], spans = getLine(this, pos.line).markedSpans;
    if (spans) for (var i = 0; i < spans.length; ++i) {
      var span = spans[i];
      if ((span.from == null || span.from <= pos.ch) &&
          (span.to == null || span.to >= pos.ch))
        markers.push(span.marker.parent || span.marker);
    }
    return markers;
  },
  findMarks: function(from, to, filter) {
    from = clipPos(this, from); to = clipPos(this, to);
    var found = [], lineNo = from.line;
    this.iter(from.line, to.line + 1, function(line) {
      var spans = line.markedSpans;
      if (spans) for (var i = 0; i < spans.length; i++) {
        var span = spans[i];
        if (!(lineNo == from.line && from.ch > span.to ||
              span.from == null && lineNo != from.line||
              lineNo == to.line && span.from > to.ch) &&
            (!filter || filter(span.marker)))
          found.push(span.marker.parent || span.marker);
      }
      ++lineNo;
    });
    return found;
  },
  getAllMarks: function() {
    var markers = [];
    this.iter(function(line) {
      var sps = line.markedSpans;
      if (sps) for (var i = 0; i < sps.length; ++i)
        if (sps[i].from != null) markers.push(sps[i].marker);
    });
    return markers;
  },

  posFromIndex: function(off) {
    var ch, lineNo = this.first;
    this.iter(function(line) {
      var sz = line.text.length + 1;
      if (sz > off) { ch = off; return true; }
      off -= sz;
      ++lineNo;
    });
    return clipPos(this, Pos(lineNo, ch));
  },
  indexFromPos: function (coords) {
    coords = clipPos(this, coords);
    var index = coords.ch;
    if (coords.line < this.first || coords.ch < 0) return 0;
    this.iter(this.first, coords.line, function (line) {
      index += line.text.length + 1;
    });
    return index;
  },

  copy: function(copyHistory) {
    var doc = new Doc(getLines(this, this.first, this.first + this.size), this.modeOption, this.first);
    doc.scrollTop = this.scrollTop; doc.scrollLeft = this.scrollLeft;
    doc.sel = this.sel;
    doc.extend = false;
    if (copyHistory) {
      doc.history.undoDepth = this.history.undoDepth;
      doc.setHistory(this.getHistory());
    }
    return doc;
  },

  linkedDoc: function(options) {
    if (!options) options = {};
    var from = this.first, to = this.first + this.size;
    if (options.from != null && options.from > from) from = options.from;
    if (options.to != null && options.to < to) to = options.to;
    var copy = new Doc(getLines(this, from, to), options.mode || this.modeOption, from);
    if (options.sharedHist) copy.history = this.history;
    (this.linked || (this.linked = [])).push({doc: copy, sharedHist: options.sharedHist});
    copy.linked = [{doc: this, isParent: true, sharedHist: options.sharedHist}];
    copySharedMarkers(copy, findSharedMarkers(this));
    return copy;
  },
  unlinkDoc: function(other) {
    if (other instanceof CodeMirror) other = other.doc;
    if (this.linked) for (var i = 0; i < this.linked.length; ++i) {
      var link = this.linked[i];
      if (link.doc != other) continue;
      this.linked.splice(i, 1);
      other.unlinkDoc(this);
      detachSharedMarkers(findSharedMarkers(this));
      break;
    }
    // If the histories were shared, split them again
    if (other.history == this.history) {
      var splitIds = [other.id];
      linkedDocs(other, function(doc) {splitIds.push(doc.id);}, true);
      other.history = new History(null);
      other.history.done = copyHistoryArray(this.history.done, splitIds);
      other.history.undone = copyHistoryArray(this.history.undone, splitIds);
    }
  },
  iterLinkedDocs: function(f) {linkedDocs(this, f);},

  getMode: function() {return this.mode;},
  getEditor: function() {return this.cm;}
});

// Public alias.
Doc.prototype.eachLine = Doc.prototype.iter;

// Set up methods on CodeMirror's prototype to redirect to the editor's document.
var dontDelegate = "iter insert remove copy getEditor".split(" ");
for (var prop in Doc.prototype) if (Doc.prototype.hasOwnProperty(prop) && indexOf(dontDelegate, prop) < 0)
  CodeMirror.prototype[prop] = (function(method) {
    return function() {return method.apply(this.doc, arguments);};
  })(Doc.prototype[prop]);

eventMixin(Doc);

// Call f for all linked documents.
function linkedDocs(doc, f, sharedHistOnly) {
  function propagate(doc, skip, sharedHist) {
    if (doc.linked) for (var i = 0; i < doc.linked.length; ++i) {
      var rel = doc.linked[i];
      if (rel.doc == skip) continue;
      var shared = sharedHist && rel.sharedHist;
      if (sharedHistOnly && !shared) continue;
      f(rel.doc, shared);
      propagate(rel.doc, doc, shared);
    }
  }
  propagate(doc, null, true);
}

// Attach a document to an editor.
function attachDoc(cm, doc) {
  if (doc.cm) throw new Error("This document is already in use.");
  cm.doc = doc;
  doc.cm = cm;
  estimateLineHeights(cm);
  loadMode(cm);
  if (!cm.options.lineWrapping) findMaxLine(cm);
  cm.options.mode = doc.modeOption;
  regChange(cm);
}

// LINE UTILITIES

// Find the line object corresponding to the given line number.
function getLine(doc, n) {
  n -= doc.first;
  if (n < 0 || n >= doc.size) throw new Error("There is no line " + (n + doc.first) + " in the document.");
  for (var chunk = doc; !chunk.lines;) {
    for (var i = 0;; ++i) {
      var child = chunk.children[i], sz = child.chunkSize();
      if (n < sz) { chunk = child; break; }
      n -= sz;
    }
  }
  return chunk.lines[n];
}

// Get the part of a document between two positions, as an array of
// strings.
function getBetween(doc, start, end) {
  var out = [], n = start.line;
  doc.iter(start.line, end.line + 1, function(line) {
    var text = line.text;
    if (n == end.line) text = text.slice(0, end.ch);
    if (n == start.line) text = text.slice(start.ch);
    out.push(text);
    ++n;
  });
  return out;
}
// Get the lines between from and to, as array of strings.
function getLines(doc, from, to) {
  var out = [];
  doc.iter(from, to, function(line) { out.push(line.text); });
  return out;
}

// Update the height of a line, propagating the height change
// upwards to parent nodes.
function updateLineHeight(line, height) {
  var diff = height - line.height;
  if (diff) for (var n = line; n; n = n.parent) n.height += diff;
}

// Given a line object, find its line number by walking up through
// its parent links.
function lineNo(line) {
  if (line.parent == null) return null;
  var cur = line.parent, no = indexOf(cur.lines, line);
  for (var chunk = cur.parent; chunk; cur = chunk, chunk = chunk.parent) {
    for (var i = 0;; ++i) {
      if (chunk.children[i] == cur) break;
      no += chunk.children[i].chunkSize();
    }
  }
  return no + cur.first;
}

// Find the line at the given vertical position, using the height
// information in the document tree.
function lineAtHeight(chunk, h) {
  var n = chunk.first;
  outer: do {
    for (var i = 0; i < chunk.children.length; ++i) {
      var child = chunk.children[i], ch = child.height;
      if (h < ch) { chunk = child; continue outer; }
      h -= ch;
      n += child.chunkSize();
    }
    return n;
  } while (!chunk.lines);
  for (var i = 0; i < chunk.lines.length; ++i) {
    var line = chunk.lines[i], lh = line.height;
    if (h < lh) break;
    h -= lh;
  }
  return n + i;
}

// Find the height above the given line.
function heightAtLine(lineObj) {
  lineObj = visualLine(lineObj);

  var h = 0, chunk = lineObj.parent;
  for (var i = 0; i < chunk.lines.length; ++i) {
    var line = chunk.lines[i];
    if (line == lineObj) break;
    else h += line.height;
  }
  for (var p = chunk.parent; p; chunk = p, p = chunk.parent) {
    for (var i = 0; i < p.children.length; ++i) {
      var cur = p.children[i];
      if (cur == chunk) break;
      else h += cur.height;
    }
  }
  return h;
}

// Get the bidi ordering for the given line (and cache it). Returns
// false for lines that are fully left-to-right, and an array of
// BidiSpan objects otherwise.
function getOrder(line) {
  var order = line.order;
  if (order == null) order = line.order = bidiOrdering(line.text);
  return order;
}

// HISTORY

function History(startGen) {
  // Arrays of change events and selections. Doing something adds an
  // event to done and clears undo. Undoing moves events from done
  // to undone, redoing moves them in the other direction.
  this.done = []; this.undone = [];
  this.undoDepth = Infinity;
  // Used to track when changes can be merged into a single undo
  // event
  this.lastModTime = this.lastSelTime = 0;
  this.lastOp = this.lastSelOp = null;
  this.lastOrigin = this.lastSelOrigin = null;
  // Used by the isClean() method
  this.generation = this.maxGeneration = startGen || 1;
}

// Create a history change event from an updateDoc-style change
// object.
function historyChangeFromChange(doc, change) {
  var histChange = {from: copyPos(change.from), to: changeEnd(change), text: getBetween(doc, change.from, change.to)};
  attachLocalSpans(doc, histChange, change.from.line, change.to.line + 1);
  linkedDocs(doc, function(doc) {attachLocalSpans(doc, histChange, change.from.line, change.to.line + 1);}, true);
  return histChange;
}

// Pop all selection events off the end of a history array. Stop at
// a change event.
function clearSelectionEvents(array) {
  while (array.length) {
    var last = lst(array);
    if (last.ranges) array.pop();
    else break;
  }
}

// Find the top change event in the history. Pop off selection
// events that are in the way.
function lastChangeEvent(hist, force) {
  if (force) {
    clearSelectionEvents(hist.done);
    return lst(hist.done);
  } else if (hist.done.length && !lst(hist.done).ranges) {
    return lst(hist.done);
  } else if (hist.done.length > 1 && !hist.done[hist.done.length - 2].ranges) {
    hist.done.pop();
    return lst(hist.done);
  }
}

// Register a change in the history. Merges changes that are within
// a single operation, ore are close together with an origin that
// allows merging (starting with "+") into a single event.
function addChangeToHistory(doc, change, selAfter, opId) {
  var hist = doc.history;
  hist.undone.length = 0;
  var time = +new Date, cur;

  if ((hist.lastOp == opId ||
       hist.lastOrigin == change.origin && change.origin &&
       ((change.origin.charAt(0) == "+" && doc.cm && hist.lastModTime > time - doc.cm.options.historyEventDelay) ||
        change.origin.charAt(0) == "*")) &&
      (cur = lastChangeEvent(hist, hist.lastOp == opId))) {
    // Merge this change into the last event
    var last = lst(cur.changes);
    if (cmp(change.from, change.to) == 0 && cmp(change.from, last.to) == 0) {
      // Optimized case for simple insertion -- don't want to add
      // new changesets for every character typed
      last.to = changeEnd(change);
    } else {
      // Add new sub-event
      cur.changes.push(historyChangeFromChange(doc, change));
    }
  } else {
    // Can not be merged, start a new event.
    var before = lst(hist.done);
    if (!before || !before.ranges)
      pushSelectionToHistory(doc.sel, hist.done);
    cur = {changes: [historyChangeFromChange(doc, change)],
           generation: hist.generation};
    hist.done.push(cur);
    while (hist.done.length > hist.undoDepth) {
      hist.done.shift();
      if (!hist.done[0].ranges) hist.done.shift();
    }
  }
  hist.done.push(selAfter);
  hist.generation = ++hist.maxGeneration;
  hist.lastModTime = hist.lastSelTime = time;
  hist.lastOp = hist.lastSelOp = opId;
  hist.lastOrigin = hist.lastSelOrigin = change.origin;

  if (!last) signal(doc, "historyAdded");
}

function selectionEventCanBeMerged(doc, origin, prev, sel) {
  var ch = origin.charAt(0);
  return ch == "*" ||
    ch == "+" &&
    prev.ranges.length == sel.ranges.length &&
    prev.somethingSelected() == sel.somethingSelected() &&
    new Date - doc.history.lastSelTime <= (doc.cm ? doc.cm.options.historyEventDelay : 500);
}

// Called whenever the selection changes, sets the new selection as
// the pending selection in the history, and pushes the old pending
// selection into the 'done' array when it was significantly
// different (in number of selected ranges, emptiness, or time).
function addSelectionToHistory(doc, sel, opId, options) {
  var hist = doc.history, origin = options && options.origin;

  // A new event is started when the previous origin does not match
  // the current, or the origins don't allow matching. Origins
  // starting with * are always merged, those starting with + are
  // merged when similar and close together in time.
  if (opId == hist.lastSelOp ||
      (origin && hist.lastSelOrigin == origin &&
       (hist.lastModTime == hist.lastSelTime && hist.lastOrigin == origin ||
        selectionEventCanBeMerged(doc, origin, lst(hist.done), sel))))
    hist.done[hist.done.length - 1] = sel;
  else
    pushSelectionToHistory(sel, hist.done);

  hist.lastSelTime = +new Date;
  hist.lastSelOrigin = origin;
  hist.lastSelOp = opId;
  if (options && options.clearRedo !== false)
    clearSelectionEvents(hist.undone);
}

function pushSelectionToHistory(sel, dest) {
  var top = lst(dest);
  if (!(top && top.ranges && top.equals(sel)))
    dest.push(sel);
}

// Used to store marked span information in the history.
function attachLocalSpans(doc, change, from, to) {
  var existing = change["spans_" + doc.id], n = 0;
  doc.iter(Math.max(doc.first, from), Math.min(doc.first + doc.size, to), function(line) {
    if (line.markedSpans)
      (existing || (existing = change["spans_" + doc.id] = {}))[n] = line.markedSpans;
    ++n;
  });
}

// When un/re-doing restores text containing marked spans, those
// that have been explicitly cleared should not be restored.
function removeClearedSpans(spans) {
  if (!spans) return null;
  for (var i = 0, out; i < spans.length; ++i) {
    if (spans[i].marker.explicitlyCleared) { if (!out) out = spans.slice(0, i); }
    else if (out) out.push(spans[i]);
  }
  return !out ? spans : out.length ? out : null;
}

// Retrieve and filter the old marked spans stored in a change event.
function getOldSpans(doc, change) {
  var found = change["spans_" + doc.id];
  if (!found) return null;
  for (var i = 0, nw = []; i < change.text.length; ++i)
    nw.push(removeClearedSpans(found[i]));
  return nw;
}

// Used both to provide a JSON-safe object in .getHistory, and, when
// detaching a document, to split the history in two
function copyHistoryArray(events, newGroup, instantiateSel) {
  for (var i = 0, copy = []; i < events.length; ++i) {
    var event = events[i];
    if (event.ranges) {
      copy.push(instantiateSel ? Selection.prototype.deepCopy.call(event) : event);
      continue;
    }
    var changes = event.changes, newChanges = [];
    copy.push({changes: newChanges});
    for (var j = 0; j < changes.length; ++j) {
      var change = changes[j], m;
      newChanges.push({from: change.from, to: change.to, text: change.text});
      if (newGroup) for (var prop in change) if (m = prop.match(/^spans_(\d+)$/)) {
        if (indexOf(newGroup, Number(m[1])) > -1) {
          lst(newChanges)[prop] = change[prop];
          delete change[prop];
        }
      }
    }
  }
  return copy;
}

// Rebasing/resetting history to deal with externally-sourced changes

function rebaseHistSelSingle(pos, from, to, diff) {
  if (to < pos.line) {
    pos.line += diff;
  } else if (from < pos.line) {
    pos.line = from;
    pos.ch = 0;
  }
}

// Tries to rebase an array of history events given a change in the
// document. If the change touches the same lines as the event, the
// event, and everything 'behind' it, is discarded. If the change is
// before the event, the event's positions are updated. Uses a
// copy-on-write scheme for the positions, to avoid having to
// reallocate them all on every rebase, but also avoid problems with
// shared position objects being unsafely updated.
function rebaseHistArray(array, from, to, diff) {
  for (var i = 0; i < array.length; ++i) {
    var sub = array[i], ok = true;
    if (sub.ranges) {
      if (!sub.copied) { sub = array[i] = sub.deepCopy(); sub.copied = true; }
      for (var j = 0; j < sub.ranges.length; j++) {
        rebaseHistSelSingle(sub.ranges[j].anchor, from, to, diff);
        rebaseHistSelSingle(sub.ranges[j].head, from, to, diff);
      }
      continue;
    }
    for (var j = 0; j < sub.changes.length; ++j) {
      var cur = sub.changes[j];
      if (to < cur.from.line) {
        cur.from = Pos(cur.from.line + diff, cur.from.ch);
        cur.to = Pos(cur.to.line + diff, cur.to.ch);
      } else if (from <= cur.to.line) {
        ok = false;
        break;
      }
    }
    if (!ok) {
      array.splice(0, i + 1);
      i = 0;
    }
  }
}

function rebaseHist(hist, change) {
  var from = change.from.line, to = change.to.line, diff = change.text.length - (to - from) - 1;
  rebaseHistArray(hist.done, from, to, diff);
  rebaseHistArray(hist.undone, from, to, diff);
}

// EVENT UTILITIES

// Due to the fact that we still support jurassic IE versions, some
// compatibility wrappers are needed.

var e_preventDefault = CodeMirror.e_preventDefault = function(e) {
  if (e.preventDefault) e.preventDefault();
  else e.returnValue = false;
};
var e_stopPropagation = CodeMirror.e_stopPropagation = function(e) {
  if (e.stopPropagation) e.stopPropagation();
  else e.cancelBubble = true;
};
function e_defaultPrevented(e) {
  return e.defaultPrevented != null ? e.defaultPrevented : e.returnValue == false;
}
var e_stop = CodeMirror.e_stop = function(e) {e_preventDefault(e); e_stopPropagation(e);};

function e_target(e) {return e.target || e.srcElement;}
function e_button(e) {
  var b = e.which;
  if (b == null) {
    if (e.button & 1) b = 1;
    else if (e.button & 2) b = 3;
    else if (e.button & 4) b = 2;
  }
  if (mac && e.ctrlKey && b == 1) b = 3;
  return b;
}

// EVENT HANDLING

// Lightweight event framework. on/off also work on DOM nodes,
// registering native DOM handlers.

var on = CodeMirror.on = function(emitter, type, f) {
  if (emitter.addEventListener)
    emitter.addEventListener(type, f, false);
  else if (emitter.attachEvent)
    emitter.attachEvent("on" + type, f);
  else {
    var map = emitter._handlers || (emitter._handlers = {});
    var arr = map[type] || (map[type] = []);
    arr.push(f);
  }
};

var off = CodeMirror.off = function(emitter, type, f) {
  if (emitter.removeEventListener)
    emitter.removeEventListener(type, f, false);
  else if (emitter.detachEvent)
    emitter.detachEvent("on" + type, f);
  else {
    var arr = emitter._handlers && emitter._handlers[type];
    if (!arr) return;
    for (var i = 0; i < arr.length; ++i)
      if (arr[i] == f) { arr.splice(i, 1); break; }
  }
};

var signal = CodeMirror.signal = function(emitter, type /*, values...*/) {
  var arr = emitter._handlers && emitter._handlers[type];
  if (!arr) return;
  var args = Array.prototype.slice.call(arguments, 2);
  for (var i = 0; i < arr.length; ++i) arr[i].apply(null, args);
};

var orphanDelayedCallbacks = null;

// Often, we want to signal events at a point where we are in the
// middle of some work, but don't want the handler to start calling
// other methods on the editor, which might be in an inconsistent
// state or simply not expect any other events to happen.
// signalLater looks whether there are any handlers, and schedules
// them to be executed when the last operation ends, or, if no
// operation is active, when a timeout fires.
function signalLater(emitter, type /*, values...*/) {
  var arr = emitter._handlers && emitter._handlers[type];
  if (!arr) return;
  var args = Array.prototype.slice.call(arguments, 2), list;
  if (operationGroup) {
    list = operationGroup.delayedCallbacks;
  } else if (orphanDelayedCallbacks) {
    list = orphanDelayedCallbacks;
  } else {
    list = orphanDelayedCallbacks = [];
    setTimeout(fireOrphanDelayed, 0);
  }
  function bnd(f) {return function(){f.apply(null, args);};};
  for (var i = 0; i < arr.length; ++i)
    list.push(bnd(arr[i]));
}

function fireOrphanDelayed() {
  var delayed = orphanDelayedCallbacks;
  orphanDelayedCallbacks = null;
  for (var i = 0; i < delayed.length; ++i) delayed[i]();
}

// The DOM events that CodeMirror handles can be overridden by
// registering a (non-DOM) handler on the editor for the event name,
// and preventDefault-ing the event in that handler.
function signalDOMEvent(cm, e, override) {
  signal(cm, override || e.type, cm, e);
  return e_defaultPrevented(e) || e.codemirrorIgnore;
}

function signalCursorActivity(cm) {
  var arr = cm._handlers && cm._handlers.cursorActivity;
  if (!arr) return;
  var set = cm.curOp.cursorActivityHandlers || (cm.curOp.cursorActivityHandlers = []);
  for (var i = 0; i < arr.length; ++i) if (indexOf(set, arr[i]) == -1)
    set.push(arr[i]);
}

function hasHandler(emitter, type) {
  var arr = emitter._handlers && emitter._handlers[type];
  return arr && arr.length > 0;
}

// Add on and off methods to a constructor's prototype, to make
// registering events on such objects more convenient.
function eventMixin(ctor) {
  ctor.prototype.on = function(type, f) {on(this, type, f);};
  ctor.prototype.off = function(type, f) {off(this, type, f);};
}

// MISC UTILITIES

// Number of pixels added to scroller and sizer to hide scrollbar
var scrollerCutOff = 30;

// Returned or thrown by various protocols to signal 'I'm not
// handling this'.
var Pass = CodeMirror.Pass = {toString: function(){return "CodeMirror.Pass";}};

// Reused option objects for setSelection & friends
var sel_dontScroll = {scroll: false}, sel_mouse = {origin: "*mouse"}, sel_move = {origin: "+move"};

function Delayed() {this.id = null;}
Delayed.prototype.set = function(ms, f) {
  clearTimeout(this.id);
  this.id = setTimeout(f, ms);
};

// Counts the column offset in a string, taking tabs into account.
// Used mostly to find indentation.
var countColumn = CodeMirror.countColumn = function(string, end, tabSize, startIndex, startValue) {
  if (end == null) {
    end = string.search(/[^\s\u00a0]/);
    if (end == -1) end = string.length;
  }
  for (var i = startIndex || 0, n = startValue || 0;;) {
    var nextTab = string.indexOf("\t", i);
    if (nextTab < 0 || nextTab >= end)
      return n + (end - i);
    n += nextTab - i;
    n += tabSize - (n % tabSize);
    i = nextTab + 1;
  }
};

// The inverse of countColumn -- find the offset that corresponds to
// a particular column.
function findColumn(string, goal, tabSize) {
  for (var pos = 0, col = 0;;) {
    var nextTab = string.indexOf("\t", pos);
    if (nextTab == -1) nextTab = string.length;
    var skipped = nextTab - pos;
    if (nextTab == string.length || col + skipped >= goal)
      return pos + Math.min(skipped, goal - col);
    col += nextTab - pos;
    col += tabSize - (col % tabSize);
    pos = nextTab + 1;
    if (col >= goal) return pos;
  }
}

var spaceStrs = [""];
function spaceStr(n) {
  while (spaceStrs.length <= n)
    spaceStrs.push(lst(spaceStrs) + " ");
  return spaceStrs[n];
}

function lst(arr) { return arr[arr.length-1]; }

var selectInput = function(node) { node.select(); };
if (ios) // Mobile Safari apparently has a bug where select() is broken.
  selectInput = function(node) { node.selectionStart = 0; node.selectionEnd = node.value.length; };
else if (ie) // Suppress mysterious IE10 errors
  selectInput = function(node) { try { node.select(); } catch(_e) {} };

function indexOf(array, elt) {
  for (var i = 0; i < array.length; ++i)
    if (array[i] == elt) return i;
  return -1;
}
if ([].indexOf) indexOf = function(array, elt) { return array.indexOf(elt); };
function map(array, f) {
  var out = [];
  for (var i = 0; i < array.length; i++) out[i] = f(array[i], i);
  return out;
}
if ([].map) map = function(array, f) { return array.map(f); };

function createObj(base, props) {
  var inst;
  if (Object.create) {
    inst = Object.create(base);
  } else {
    var ctor = function() {};
    ctor.prototype = base;
    inst = new ctor();
  }
  if (props) copyObj(props, inst);
  return inst;
};

function copyObj(obj, target, overwrite) {
  if (!target) target = {};
  for (var prop in obj)
    if (obj.hasOwnProperty(prop) && (overwrite !== false || !target.hasOwnProperty(prop)))
      target[prop] = obj[prop];
  return target;
}

function bind(f) {
  var args = Array.prototype.slice.call(arguments, 1);
  return function(){return f.apply(null, args);};
}

var nonASCIISingleCaseWordChar = /[\u00df\u3040-\u309f\u30a0-\u30ff\u3400-\u4db5\u4e00-\u9fcc\uac00-\ud7af]/;
var isWordCharBasic = CodeMirror.isWordChar = function(ch) {
  return /\w/.test(ch) || ch > "\x80" &&
    (ch.toUpperCase() != ch.toLowerCase() || nonASCIISingleCaseWordChar.test(ch));
};
function isWordChar(ch, helper) {
  if (!helper) return isWordCharBasic(ch);
  if (helper.source.indexOf("\\w") > -1 && isWordCharBasic(ch)) return true;
  return helper.test(ch);
}

function isEmpty(obj) {
  for (var n in obj) if (obj.hasOwnProperty(n) && obj[n]) return false;
  return true;
}

// Extending unicode characters. A series of a non-extending char +
// any number of extending chars is treated as a single unit as far
// as editing and measuring is concerned. This is not fully correct,
// since some scripts/fonts/browsers also treat other configurations
// of code points as a group.
var extendingChars = /[\u0300-\u036f\u0483-\u0489\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u064b-\u065e\u0670\u06d6-\u06dc\u06de-\u06e4\u06e7\u06e8\u06ea-\u06ed\u0711\u0730-\u074a\u07a6-\u07b0\u07eb-\u07f3\u0816-\u0819\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0900-\u0902\u093c\u0941-\u0948\u094d\u0951-\u0955\u0962\u0963\u0981\u09bc\u09be\u09c1-\u09c4\u09cd\u09d7\u09e2\u09e3\u0a01\u0a02\u0a3c\u0a41\u0a42\u0a47\u0a48\u0a4b-\u0a4d\u0a51\u0a70\u0a71\u0a75\u0a81\u0a82\u0abc\u0ac1-\u0ac5\u0ac7\u0ac8\u0acd\u0ae2\u0ae3\u0b01\u0b3c\u0b3e\u0b3f\u0b41-\u0b44\u0b4d\u0b56\u0b57\u0b62\u0b63\u0b82\u0bbe\u0bc0\u0bcd\u0bd7\u0c3e-\u0c40\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62\u0c63\u0cbc\u0cbf\u0cc2\u0cc6\u0ccc\u0ccd\u0cd5\u0cd6\u0ce2\u0ce3\u0d3e\u0d41-\u0d44\u0d4d\u0d57\u0d62\u0d63\u0dca\u0dcf\u0dd2-\u0dd4\u0dd6\u0ddf\u0e31\u0e34-\u0e3a\u0e47-\u0e4e\u0eb1\u0eb4-\u0eb9\u0ebb\u0ebc\u0ec8-\u0ecd\u0f18\u0f19\u0f35\u0f37\u0f39\u0f71-\u0f7e\u0f80-\u0f84\u0f86\u0f87\u0f90-\u0f97\u0f99-\u0fbc\u0fc6\u102d-\u1030\u1032-\u1037\u1039\u103a\u103d\u103e\u1058\u1059\u105e-\u1060\u1071-\u1074\u1082\u1085\u1086\u108d\u109d\u135f\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17b7-\u17bd\u17c6\u17c9-\u17d3\u17dd\u180b-\u180d\u18a9\u1920-\u1922\u1927\u1928\u1932\u1939-\u193b\u1a17\u1a18\u1a56\u1a58-\u1a5e\u1a60\u1a62\u1a65-\u1a6c\u1a73-\u1a7c\u1a7f\u1b00-\u1b03\u1b34\u1b36-\u1b3a\u1b3c\u1b42\u1b6b-\u1b73\u1b80\u1b81\u1ba2-\u1ba5\u1ba8\u1ba9\u1c2c-\u1c33\u1c36\u1c37\u1cd0-\u1cd2\u1cd4-\u1ce0\u1ce2-\u1ce8\u1ced\u1dc0-\u1de6\u1dfd-\u1dff\u200c\u200d\u20d0-\u20f0\u2cef-\u2cf1\u2de0-\u2dff\u302a-\u302f\u3099\u309a\ua66f-\ua672\ua67c\ua67d\ua6f0\ua6f1\ua802\ua806\ua80b\ua825\ua826\ua8c4\ua8e0-\ua8f1\ua926-\ua92d\ua947-\ua951\ua980-\ua982\ua9b3\ua9b6-\ua9b9\ua9bc\uaa29-\uaa2e\uaa31\uaa32\uaa35\uaa36\uaa43\uaa4c\uaab0\uaab2-\uaab4\uaab7\uaab8\uaabe\uaabf\uaac1\uabe5\uabe8\uabed\udc00-\udfff\ufb1e\ufe00-\ufe0f\ufe20-\ufe26\uff9e\uff9f]/;
function isExtendingChar(ch) { return ch.charCodeAt(0) >= 768 && extendingChars.test(ch); }

// DOM UTILITIES

function elt(tag, content, className, style) {
  var e = document.createElement(tag);
  if (className) e.className = className;
  if (style) e.style.cssText = style;
  if (typeof content == "string") e.appendChild(document.createTextNode(content));
  else if (content) for (var i = 0; i < content.length; ++i) e.appendChild(content[i]);
  return e;
}

var range;
if (document.createRange) range = function(node, start, end) {
  var r = document.createRange();
  r.setEnd(node, end);
  r.setStart(node, start);
  return r;
};
else range = function(node, start, end) {
  var r = document.body.createTextRange();
  r.moveToElementText(node.parentNode);
  r.collapse(true);
  r.moveEnd("character", end);
  r.moveStart("character", start);
  return r;
};

function removeChildren(e) {
  for (var count = e.childNodes.length; count > 0; --count)
    e.removeChild(e.firstChild);
  return e;
}

function removeChildrenAndAdd(parent, e) {
  return removeChildren(parent).appendChild(e);
}

function contains(parent, child) {
  if (parent.contains)
    return parent.contains(child);
  while (child = child.parentNode)
    if (child == parent) return true;
}

function activeElt() { return document.activeElement; }
// Older versions of IE throws unspecified error when touching
// document.activeElement in some cases (during loading, in iframe)
if (ie && ie_version < 11) activeElt = function() {
  try { return document.activeElement; }
  catch(e) { return document.body; }
};

function classTest(cls) { return new RegExp("\\b" + cls + "\\b\\s*"); }
function rmClass(node, cls) {
  var test = classTest(cls);
  if (test.test(node.className)) node.className = node.className.replace(test, "");
}
function addClass(node, cls) {
  if (!classTest(cls).test(node.className)) node.className += " " + cls;
}
function joinClasses(a, b) {
  var as = a.split(" ");
  for (var i = 0; i < as.length; i++)
    if (as[i] && !classTest(as[i]).test(b)) b += " " + as[i];
  return b;
}

// WINDOW-WIDE EVENTS

// These must be handled carefully, because naively registering a
// handler for each editor will cause the editors to never be
// garbage collected.

function forEachCodeMirror(f) {
  if (!document.body.getElementsByClassName) return;
  var byClass = document.body.getElementsByClassName("CodeMirror");
  for (var i = 0; i < byClass.length; i++) {
    var cm = byClass[i].CodeMirror;
    if (cm) f(cm);
  }
}

var globalsRegistered = false;
function ensureGlobalHandlers() {
  if (globalsRegistered) return;
  registerGlobalHandlers();
  globalsRegistered = true;
}
function registerGlobalHandlers() {
  // When the window resizes, we need to refresh active editors.
  var resizeTimer;
  on(window, "resize", function() {
    if (resizeTimer == null) resizeTimer = setTimeout(function() {
      resizeTimer = null;
      knownScrollbarWidth = null;
      forEachCodeMirror(onResize);
    }, 100);
  });
  // When the window loses focus, we want to show the editor as blurred
  on(window, "blur", function() {
    forEachCodeMirror(onBlur);
  });
}

// FEATURE DETECTION

// Detect drag-and-drop
var dragAndDrop = function() {
  // There is *some* kind of drag-and-drop support in IE6-8, but I
  // couldn't get it to work yet.
  if (ie && ie_version < 9) return false;
  var div = elt('div');
  return "draggable" in div || "dragDrop" in div;
}();

var knownScrollbarWidth;
function scrollbarWidth(measure) {
  if (knownScrollbarWidth != null) return knownScrollbarWidth;
  var test = elt("div", null, null, "width: 50px; height: 50px; overflow-x: scroll");
  removeChildrenAndAdd(measure, test);
  if (test.offsetWidth)
    knownScrollbarWidth = test.offsetHeight - test.clientHeight;
  return knownScrollbarWidth || 0;
}

var zwspSupported;
function zeroWidthElement(measure) {
  if (zwspSupported == null) {
    var test = elt("span", "\u200b");
    removeChildrenAndAdd(measure, elt("span", [test, document.createTextNode("x")]));
    if (measure.firstChild.offsetHeight != 0)
      zwspSupported = test.offsetWidth <= 1 && test.offsetHeight > 2 && !(ie && ie_version < 8);
  }
  if (zwspSupported) return elt("span", "\u200b");
  else return elt("span", "\u00a0", null, "display: inline-block; width: 1px; margin-right: -1px");
}

// Feature-detect IE's crummy client rect reporting for bidi text
var badBidiRects;
function hasBadBidiRects(measure) {
  if (badBidiRects != null) return badBidiRects;
  var txt = removeChildrenAndAdd(measure, document.createTextNode("A\u062eA"));
  var r0 = range(txt, 0, 1).getBoundingClientRect();
  if (r0.left == r0.right) return false;
  var r1 = range(txt, 1, 2).getBoundingClientRect();
  return badBidiRects = (r1.right - r0.right < 3);
}

// See if "".split is the broken IE version, if so, provide an
// alternative way to split lines.
var splitLines = CodeMirror.splitLines = "\n\nb".split(/\n/).length != 3 ? function(string) {
  var pos = 0, result = [], l = string.length;
  while (pos <= l) {
    var nl = string.indexOf("\n", pos);
    if (nl == -1) nl = string.length;
    var line = string.slice(pos, string.charAt(nl - 1) == "\r" ? nl - 1 : nl);
    var rt = line.indexOf("\r");
    if (rt != -1) {
      result.push(line.slice(0, rt));
      pos += rt + 1;
    } else {
      result.push(line);
      pos = nl + 1;
    }
  }
  return result;
} : function(string){return string.split(/\r\n?|\n/);};

var hasSelection = window.getSelection ? function(te) {
  try { return te.selectionStart != te.selectionEnd; }
  catch(e) { return false; }
} : function(te) {
  try {var range = te.ownerDocument.selection.createRange();}
  catch(e) {}
  if (!range || range.parentElement() != te) return false;
  return range.compareEndPoints("StartToEnd", range) != 0;
};

var hasCopyEvent = (function() {
  var e = elt("div");
  if ("oncopy" in e) return true;
  e.setAttribute("oncopy", "return;");
  return typeof e.oncopy == "function";
})();

var badZoomedRects = null;
function hasBadZoomedRects(measure) {
  if (badZoomedRects != null) return badZoomedRects;
  var node = removeChildrenAndAdd(measure, elt("span", "x"));
  var normal = node.getBoundingClientRect();
  var fromRange = range(node, 0, 1).getBoundingClientRect();
  return badZoomedRects = Math.abs(normal.left - fromRange.left) > 1;
}

// KEY NAMES

var keyNames = {3: "Enter", 8: "Backspace", 9: "Tab", 13: "Enter", 16: "Shift", 17: "Ctrl", 18: "Alt",
                19: "Pause", 20: "CapsLock", 27: "Esc", 32: "Space", 33: "PageUp", 34: "PageDown", 35: "End",
                36: "Home", 37: "Left", 38: "Up", 39: "Right", 40: "Down", 44: "PrintScrn", 45: "Insert",
                46: "Delete", 59: ";", 61: "=", 91: "Mod", 92: "Mod", 93: "Mod", 107: "=", 109: "-", 127: "Delete",
                173: "-", 186: ";", 187: "=", 188: ",", 189: "-", 190: ".", 191: "/", 192: "`", 219: "[", 220: "\\",
                221: "]", 222: "'", 63232: "Up", 63233: "Down", 63234: "Left", 63235: "Right", 63272: "Delete",
                63273: "Home", 63275: "End", 63276: "PageUp", 63277: "PageDown", 63302: "Insert"};
CodeMirror.keyNames = keyNames;
(function() {
  // Number keys
  for (var i = 0; i < 10; i++) keyNames[i + 48] = keyNames[i + 96] = String(i);
  // Alphabetic keys
  for (var i = 65; i <= 90; i++) keyNames[i] = String.fromCharCode(i);
  // Function keys
  for (var i = 1; i <= 12; i++) keyNames[i + 111] = keyNames[i + 63235] = "F" + i;
})();

// BIDI HELPERS

function iterateBidiSections(order, from, to, f) {
  if (!order) return f(from, to, "ltr");
  var found = false;
  for (var i = 0; i < order.length; ++i) {
    var part = order[i];
    if (part.from < to && part.to > from || from == to && part.to == from) {
      f(Math.max(part.from, from), Math.min(part.to, to), part.level == 1 ? "rtl" : "ltr");
      found = true;
    }
  }
  if (!found) f(from, to, "ltr");
}

function bidiLeft(part) { return part.level % 2 ? part.to : part.from; }
function bidiRight(part) { return part.level % 2 ? part.from : part.to; }

function lineLeft(line) { var order = getOrder(line); return order ? bidiLeft(order[0]) : 0; }
function lineRight(line) {
  var order = getOrder(line);
  if (!order) return line.text.length;
  return bidiRight(lst(order));
}

function lineStart(cm, lineN) {
  var line = getLine(cm.doc, lineN);
  var visual = visualLine(line);
  if (visual != line) lineN = lineNo(visual);
  var order = getOrder(visual);
  var ch = !order ? 0 : order[0].level % 2 ? lineRight(visual) : lineLeft(visual);
  return Pos(lineN, ch);
}
function lineEnd(cm, lineN) {
  var merged, line = getLine(cm.doc, lineN);
  while (merged = collapsedSpanAtEnd(line)) {
    line = merged.find(1, true).line;
    lineN = null;
  }
  var order = getOrder(line);
  var ch = !order ? line.text.length : order[0].level % 2 ? lineLeft(line) : lineRight(line);
  return Pos(lineN == null ? lineNo(line) : lineN, ch);
}
function lineStartSmart(cm, pos) {
  var start = lineStart(cm, pos.line);
  var line = getLine(cm.doc, start.line);
  var order = getOrder(line);
  if (!order || order[0].level == 0) {
    var firstNonWS = Math.max(0, line.text.search(/\S/));
    var inWS = pos.line == start.line && pos.ch <= firstNonWS && pos.ch;
    return Pos(start.line, inWS ? 0 : firstNonWS);
  }
  return start;
}

function compareBidiLevel(order, a, b) {
  var linedir = order[0].level;
  if (a == linedir) return true;
  if (b == linedir) return false;
  return a < b;
}
var bidiOther;
function getBidiPartAt(order, pos) {
  bidiOther = null;
  for (var i = 0, found; i < order.length; ++i) {
    var cur = order[i];
    if (cur.from < pos && cur.to > pos) return i;
    if ((cur.from == pos || cur.to == pos)) {
      if (found == null) {
        found = i;
      } else if (compareBidiLevel(order, cur.level, order[found].level)) {
        if (cur.from != cur.to) bidiOther = found;
        return i;
      } else {
        if (cur.from != cur.to) bidiOther = i;
        return found;
      }
    }
  }
  return found;
}

function moveInLine(line, pos, dir, byUnit) {
  if (!byUnit) return pos + dir;
  do pos += dir;
  while (pos > 0 && isExtendingChar(line.text.charAt(pos)));
  return pos;
}

// This is needed in order to move 'visually' through bi-directional
// text -- i.e., pressing left should make the cursor go left, even
// when in RTL text. The tricky part is the 'jumps', where RTL and
// LTR text touch each other. This often requires the cursor offset
// to move more than one unit, in order to visually move one unit.
function moveVisually(line, start, dir, byUnit) {
  var bidi = getOrder(line);
  if (!bidi) return moveLogically(line, start, dir, byUnit);
  var pos = getBidiPartAt(bidi, start), part = bidi[pos];
  var target = moveInLine(line, start, part.level % 2 ? -dir : dir, byUnit);

  for (;;) {
    if (target > part.from && target < part.to) return target;
    if (target == part.from || target == part.to) {
      if (getBidiPartAt(bidi, target) == pos) return target;
      part = bidi[pos += dir];
      return (dir > 0) == part.level % 2 ? part.to : part.from;
    } else {
      part = bidi[pos += dir];
      if (!part) return null;
      if ((dir > 0) == part.level % 2)
        target = moveInLine(line, part.to, -1, byUnit);
      else
        target = moveInLine(line, part.from, 1, byUnit);
    }
  }
}

function moveLogically(line, start, dir, byUnit) {
  var target = start + dir;
  if (byUnit) while (target > 0 && isExtendingChar(line.text.charAt(target))) target += dir;
  return target < 0 || target > line.text.length ? null : target;
}

// Bidirectional ordering algorithm
// See http://unicode.org/reports/tr9/tr9-13.html for the algorithm
// that this (partially) implements.

// One-char codes used for character types:
// L (L):   Left-to-Right
// R (R):   Right-to-Left
// r (AL):  Right-to-Left Arabic
// 1 (EN):  European Number
// + (ES):  European Number Separator
// % (ET):  European Number Terminator
// n (AN):  Arabic Number
// , (CS):  Common Number Separator
// m (NSM): Non-Spacing Mark
// b (BN):  Boundary Neutral
// s (B):   Paragraph Separator
// t (S):   Segment Separator
// w (WS):  Whitespace
// N (ON):  Other Neutrals

// Returns null if characters are ordered as they appear
// (left-to-right), or an array of sections ({from, to, level}
// objects) in the order in which they occur visually.
var bidiOrdering = (function() {
  // Character types for codepoints 0 to 0xff
  var lowTypes = "bbbbbbbbbtstwsbbbbbbbbbbbbbbssstwNN%%%NNNNNN,N,N1111111111NNNNNNNLLLLLLLLLLLLLLLLLLLLLLLLLLNNNNNNLLLLLLLLLLLLLLLLLLLLLLLLLLNNNNbbbbbbsbbbbbbbbbbbbbbbbbbbbbbbbbb,N%%%%NNNNLNNNNN%%11NLNNN1LNNNNNLLLLLLLLLLLLLLLLLLLLLLLNLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLN";
  // Character types for codepoints 0x600 to 0x6ff
  var arabicTypes = "rrrrrrrrrrrr,rNNmmmmmmrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrmmmmmmmmmmmmmmrrrrrrrnnnnnnnnnn%nnrrrmrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrmmmmmmmmmmmmmmmmmmmNmmmm";
  function charType(code) {
    if (code <= 0xf7) return lowTypes.charAt(code);
    else if (0x590 <= code && code <= 0x5f4) return "R";
    else if (0x600 <= code && code <= 0x6ed) return arabicTypes.charAt(code - 0x600);
    else if (0x6ee <= code && code <= 0x8ac) return "r";
    else if (0x2000 <= code && code <= 0x200b) return "w";
    else if (code == 0x200c) return "b";
    else return "L";
  }

  var bidiRE = /[\u0590-\u05f4\u0600-\u06ff\u0700-\u08ac]/;
  var isNeutral = /[stwN]/, isStrong = /[LRr]/, countsAsLeft = /[Lb1n]/, countsAsNum = /[1n]/;
  // Browsers seem to always treat the boundaries of block elements as being L.
  var outerType = "L";

  function BidiSpan(level, from, to) {
    this.level = level;
    this.from = from; this.to = to;
  }

  return function(str) {
    if (!bidiRE.test(str)) return false;
    var len = str.length, types = [];
    for (var i = 0, type; i < len; ++i)
      types.push(type = charType(str.charCodeAt(i)));

    // W1. Examine each non-spacing mark (NSM) in the level run, and
    // change the type of the NSM to the type of the previous
    // character. If the NSM is at the start of the level run, it will
    // get the type of sor.
    for (var i = 0, prev = outerType; i < len; ++i) {
      var type = types[i];
      if (type == "m") types[i] = prev;
      else prev = type;
    }

    // W2. Search backwards from each instance of a European number
    // until the first strong type (R, L, AL, or sor) is found. If an
    // AL is found, change the type of the European number to Arabic
    // number.
    // W3. Change all ALs to R.
    for (var i = 0, cur = outerType; i < len; ++i) {
      var type = types[i];
      if (type == "1" && cur == "r") types[i] = "n";
      else if (isStrong.test(type)) { cur = type; if (type == "r") types[i] = "R"; }
    }

    // W4. A single European separator between two European numbers
    // changes to a European number. A single common separator between
    // two numbers of the same type changes to that type.
    for (var i = 1, prev = types[0]; i < len - 1; ++i) {
      var type = types[i];
      if (type == "+" && prev == "1" && types[i+1] == "1") types[i] = "1";
      else if (type == "," && prev == types[i+1] &&
               (prev == "1" || prev == "n")) types[i] = prev;
      prev = type;
    }

    // W5. A sequence of European terminators adjacent to European
    // numbers changes to all European numbers.
    // W6. Otherwise, separators and terminators change to Other
    // Neutral.
    for (var i = 0; i < len; ++i) {
      var type = types[i];
      if (type == ",") types[i] = "N";
      else if (type == "%") {
        for (var end = i + 1; end < len && types[end] == "%"; ++end) {}
        var replace = (i && types[i-1] == "!") || (end < len && types[end] == "1") ? "1" : "N";
        for (var j = i; j < end; ++j) types[j] = replace;
        i = end - 1;
      }
    }

    // W7. Search backwards from each instance of a European number
    // until the first strong type (R, L, or sor) is found. If an L is
    // found, then change the type of the European number to L.
    for (var i = 0, cur = outerType; i < len; ++i) {
      var type = types[i];
      if (cur == "L" && type == "1") types[i] = "L";
      else if (isStrong.test(type)) cur = type;
    }

    // N1. A sequence of neutrals takes the direction of the
    // surrounding strong text if the text on both sides has the same
    // direction. European and Arabic numbers act as if they were R in
    // terms of their influence on neutrals. Start-of-level-run (sor)
    // and end-of-level-run (eor) are used at level run boundaries.
    // N2. Any remaining neutrals take the embedding direction.
    for (var i = 0; i < len; ++i) {
      if (isNeutral.test(types[i])) {
        for (var end = i + 1; end < len && isNeutral.test(types[end]); ++end) {}
        var before = (i ? types[i-1] : outerType) == "L";
        var after = (end < len ? types[end] : outerType) == "L";
        var replace = before || after ? "L" : "R";
        for (var j = i; j < end; ++j) types[j] = replace;
        i = end - 1;
      }
    }

    // Here we depart from the documented algorithm, in order to avoid
    // building up an actual levels array. Since there are only three
    // levels (0, 1, 2) in an implementation that doesn't take
    // explicit embedding into account, we can build up the order on
    // the fly, without following the level-based algorithm.
    var order = [], m;
    for (var i = 0; i < len;) {
      if (countsAsLeft.test(types[i])) {
        var start = i;
        for (++i; i < len && countsAsLeft.test(types[i]); ++i) {}
        order.push(new BidiSpan(0, start, i));
      } else {
        var pos = i, at = order.length;
        for (++i; i < len && types[i] != "L"; ++i) {}
        for (var j = pos; j < i;) {
          if (countsAsNum.test(types[j])) {
            if (pos < j) order.splice(at, 0, new BidiSpan(1, pos, j));
            var nstart = j;
            for (++j; j < i && countsAsNum.test(types[j]); ++j) {}
            order.splice(at, 0, new BidiSpan(2, nstart, j));
            pos = j;
          } else ++j;
        }
        if (pos < i) order.splice(at, 0, new BidiSpan(1, pos, i));
      }
    }
    if (order[0].level == 1 && (m = str.match(/^\s+/))) {
      order[0].from = m[0].length;
      order.unshift(new BidiSpan(0, 0, m[0].length));
    }
    if (lst(order).level == 1 && (m = str.match(/\s+$/))) {
      lst(order).to -= m[0].length;
      order.push(new BidiSpan(0, len - m[0].length, len));
    }
    if (order[0].level != lst(order).level)
      order.push(new BidiSpan(order[0].level, len, len));

    return order;
  };
})();

// THE END

CodeMirror.version = "4.5.0";

return CodeMirror;

});