(function(){

function SearchCursor(cm, query, pos, caseFold) {
  this.atOccurrence = false; this.cm = cm;
  if (caseFold == null && typeof query == "string") caseFold = false;

  pos = pos ? cm.clipPos(pos) : {line: 0, ch: 0};
  this.pos = {from: pos, to: pos};

  // The matches method is filled in based on the type of query.
  // It takes a position and a direction, and returns an object
  // describing the next occurrence of the query, or null if no
  // more matches were found.
  if (typeof query != "string") { // Regexp match
    if (!query.global) query = new RegExp(query.source, query.ignoreCase ? "ig" : "g");
    this.matches = function(reverse, pos) {
      if (reverse) {
        query.lastIndex = 0;
        var line = cm.getLine(pos.line).slice(0, pos.ch), match = query.exec(line), start = 0;
        while (match) {
          start += match.index + 1;
          line = line.slice(start);
          query.lastIndex = 0;
          var newmatch = query.exec(line);
          if (newmatch) match = newmatch;
          else break;
        }
        start--;
      } else {
        query.lastIndex = pos.ch;
        var line = cm.getLine(pos.line), match = query.exec(line),
        start = match && match.index;
      }
      if (match)
        return {from: {line: pos.line, ch: start},
                to: {line: pos.line, ch: start + match[0].length},
                match: match};
    };
  } else { // String query
    if (caseFold) query = query.toLowerCase();
    var fold = caseFold ? function(str){return str.toLowerCase();} : function(str){return str;};
    var target = query.split("\n");
    // Different methods for single-line and multi-line queries
    if (target.length == 1)
      this.matches = function(reverse, pos) {
        var line = fold(cm.getLine(pos.line)), len = query.length, match;
        if (reverse ? (pos.ch >= len && (match = line.lastIndexOf(query, pos.ch - len)) != -1)
            : (match = line.indexOf(query, pos.ch)) != -1)
          return {from: {line: pos.line, ch: match},
                  to: {line: pos.line, ch: match + len}};
      };
    else
      this.matches = function(reverse, pos) {
        var ln = pos.line, idx = (reverse ? target.length - 1 : 0), match = target[idx], line = fold(cm.getLine(ln));
        var offsetA = (reverse ? line.indexOf(match) + match.length : line.lastIndexOf(match));
        if (reverse ? offsetA >= pos.ch || offsetA != match.length
            : offsetA <= pos.ch || offsetA != line.length - match.length)
          return;
        for (;;) {
          if (reverse ? !ln : ln == cm.lineCount() - 1) return;
          line = fold(cm.getLine(ln += reverse ? -1 : 1));
          match = target[reverse ? --idx : ++idx];
          if (idx > 0 && idx < target.length - 1) {
            if (line != match) return;
            else continue;
          }
          var offsetB = (reverse ? line.lastIndexOf(match) : line.indexOf(match) + match.length);
          if (reverse ? offsetB != line.length - match.length : offsetB != match.length)
            return;
          var start = {line: pos.line, ch: offsetA}, end = {line: ln, ch: offsetB};
          return {from: reverse ? end : start, to: reverse ? start : end};
        }
      };
  }
}

SearchCursor.prototype = {
  findNext: function() {return this.find(false);},
  findPrevious: function() {return this.find(true);},

  find: function(reverse) {
    var self = this, pos = this.cm.clipPos(reverse ? this.pos.from : this.pos.to);
    function savePosAndFail(line) {
      var pos = {line: line, ch: 0};
      self.pos = {from: pos, to: pos};
      self.atOccurrence = false;
      return false;
    }

    for (;;) {
      if (this.pos = this.matches(reverse, pos)) {
        this.atOccurrence = true;
        return this.pos.match || true;
      }
      if (reverse) {
        if (!pos.line) return savePosAndFail(0);
        pos = {line: pos.line-1, ch: this.cm.getLine(pos.line-1).length};
      }
      else {
        var maxLine = this.cm.lineCount();
        if (pos.line == maxLine - 1) return savePosAndFail(maxLine);
        pos = {line: pos.line+1, ch: 0};
      }
    }
  },

  from: function() {if (this.atOccurrence) return this.pos.from;},
  to: function() {if (this.atOccurrence) return this.pos.to;},

  replace: function(newText) {
    var self = this;
    if (this.atOccurrence)
      self.pos.to = this.cm.replaceRange(newText, self.pos.from, self.pos.to);
  }
};

CodeMirror.defineExtension("getSearchCursor", function(query, pos, caseFold) {
  return new SearchCursor(this, query, pos, caseFold);
});

})();