'use strict';

/*eslint-disable no-use-before-define*/

var common = require('./common'); var YAMLException = require('./exception'); var DEFAULT_FULL_SCHEMA = require('./schema/default_full'); var DEFAULT_SAFE_SCHEMA = require('./schema/default_safe');

var _toString = Object.prototype.toString; var _hasOwnProperty = Object.prototype.hasOwnProperty;

var CHAR_TAB = 0x09; /* Tab */ var CHAR_LINE_FEED = 0x0A; /* LF */ var CHAR_SPACE = 0x20; /* Space */ var CHAR_EXCLAMATION = 0x21; /* ! */ var CHAR_DOUBLE_QUOTE = 0x22; /* “ */ var CHAR_SHARP = 0x23; /* # */ var CHAR_PERCENT = 0x25; /* % */ var CHAR_AMPERSAND = 0x26; /* & */ var CHAR_SINGLE_QUOTE = 0x27; /* ' */ var CHAR_ASTERISK = 0x2A; /* * */ var CHAR_COMMA = 0x2C; /* , */ var CHAR_MINUS = 0x2D; /* - */ var CHAR_COLON = 0x3A; /* : */ var CHAR_GREATER_THAN = 0x3E; /* > */ var CHAR_QUESTION = 0x3F; /* ? */ var CHAR_COMMERCIAL_AT = 0x40; /* @ */ var CHAR_LEFT_SQUARE_BRACKET = 0x5B; /* [ */ var CHAR_RIGHT_SQUARE_BRACKET = 0x5D; /* ] */ var CHAR_GRAVE_ACCENT = 0x60; /* ` */ var CHAR_LEFT_CURLY_BRACKET = 0x7B; /* { */ var CHAR_VERTICAL_LINE = 0x7C; /* | */ var CHAR_RIGHT_CURLY_BRACKET = 0x7D; /* } */

var ESCAPE_SEQUENCES = {};

ESCAPE_SEQUENCES = '\0'; ESCAPE_SEQUENCES = '\a'; ESCAPE_SEQUENCES = '\b'; ESCAPE_SEQUENCES = '\t'; ESCAPE_SEQUENCES = '\n'; ESCAPE_SEQUENCES = '\v'; ESCAPE_SEQUENCES = '\f'; ESCAPE_SEQUENCES = '\r'; ESCAPE_SEQUENCES = '\e'; ESCAPE_SEQUENCES = '\“'; ESCAPE_SEQUENCES = '\\'; ESCAPE_SEQUENCES = '\N'; ESCAPE_SEQUENCES = '_'; ESCAPE_SEQUENCES = '\L'; ESCAPE_SEQUENCES = '\P';

var DEPRECATED_BOOLEANS_SYNTAX = [

'y', 'Y', 'yes', 'Yes', 'YES', 'on', 'On', 'ON',
'n', 'N', 'no', 'No', 'NO', 'off', 'Off', 'OFF'

];

function compileStyleMap(schema, map) {

var result, keys, index, length, tag, style, type;

if (map === null) return {};

result = {};
keys = Object.keys(map);

for (index = 0, length = keys.length; index < length; index += 1) {
  tag = keys[index];
  style = String(map[tag]);

  if (tag.slice(0, 2) === '!!') {
    tag = 'tag:yaml.org,2002:' + tag.slice(2);
  }
  type = schema.compiledTypeMap['fallback'][tag];

  if (type && _hasOwnProperty.call(type.styleAliases, style)) {
    style = type.styleAliases[style];
  }

  result[tag] = style;
}

return result;

}

function encodeHex(character) {

var string, handle, length;

string = character.toString(16).toUpperCase();

if (character <= 0xFF) {
  handle = 'x';
  length = 2;
} else if (character <= 0xFFFF) {
  handle = 'u';
  length = 4;
} else if (character <= 0xFFFFFFFF) {
  handle = 'U';
  length = 8;
} else {
  throw new YAMLException('code point within a string may not be greater than 0xFFFFFFFF');
}

return '\\' + handle + common.repeat('0', length - string.length) + string;

}

function State(options) {

this.schema        = options['schema'] || DEFAULT_FULL_SCHEMA;
this.indent        = Math.max(1, (options['indent'] || 2));
this.noArrayIndent = options['noArrayIndent'] || false;
this.skipInvalid   = options['skipInvalid'] || false;
this.flowLevel     = (common.isNothing(options['flowLevel']) ? -1 : options['flowLevel']);
this.styleMap      = compileStyleMap(this.schema, options['styles'] || null);
this.sortKeys      = options['sortKeys'] || false;
this.lineWidth     = options['lineWidth'] || 80;
this.noRefs        = options['noRefs'] || false;
this.noCompatMode  = options['noCompatMode'] || false;
this.condenseFlow  = options['condenseFlow'] || false;

this.implicitTypes = this.schema.compiledImplicit;
this.explicitTypes = this.schema.compiledExplicit;

this.tag = null;
this.result = '';

this.duplicates = [];
this.usedDuplicates = null;

}

// Indents every line in a string. Empty lines (n only) are not indented. function indentString(string, spaces) {

var ind = common.repeat(' ', spaces),
    position = 0,
    next = -1,
    result = '',
    line,
    length = string.length;

while (position < length) {
  next = string.indexOf('\n', position);
  if (next === -1) {
    line = string.slice(position);
    position = length;
  } else {
    line = string.slice(position, next + 1);
    position = next + 1;
  }

  if (line.length && line !== '\n') result += ind;

  result += line;
}

return result;

}

function generateNextLine(state, level) {

return '\n' + common.repeat(' ', state.indent * level);

}

function testImplicitResolving(state, str) {

var index, length, type;

for (index = 0, length = state.implicitTypes.length; index < length; index += 1) {
  type = state.implicitTypes[index];

  if (type.resolve(str)) {
    return true;
  }
}

return false;

}

// [33] s-white ::= s-space | s-tab function isWhitespace© {

return c === CHAR_SPACE || c === CHAR_TAB;

}

// Returns true if the character can be printed without escaping. // From YAML 1.2: “any allowed characters known to be non-printable // should also be escaped. [However,] This isn’t mandatory” // Derived from nb-char - t - x85 - xA0 - x2028 - x2029. function isPrintable© {

return  (0x00020 <= c && c <= 0x00007E)
    || ((0x000A1 <= c && c <= 0x00D7FF) && c !== 0x2028 && c !== 0x2029)
    || ((0x0E000 <= c && c <= 0x00FFFD) && c !== 0xFEFF /* BOM */)
    ||  (0x10000 <= c && c <= 0x10FFFF);

}

// Simplified test for values allowed after the first character in plain style. function isPlainSafe© {

// Uses a subset of nb-char - c-flow-indicator - ":" - "#"
// where nb-char ::= c-printable - b-char - c-byte-order-mark.
return isPrintable(c) && c !== 0xFEFF
  // - c-flow-indicator
  && c !== CHAR_COMMA
  && c !== CHAR_LEFT_SQUARE_BRACKET
  && c !== CHAR_RIGHT_SQUARE_BRACKET
  && c !== CHAR_LEFT_CURLY_BRACKET
  && c !== CHAR_RIGHT_CURLY_BRACKET
  // - ":" - "#"
  && c !== CHAR_COLON
  && c !== CHAR_SHARP;

}

// Simplified test for values allowed as the first character in plain style. function isPlainSafeFirst© {

// Uses a subset of ns-char - c-indicator
// where ns-char = nb-char - s-white.
return isPrintable(c) && c !== 0xFEFF
  && !isWhitespace(c) // - s-white
  // - (c-indicator ::=
  // “-” | “?” | “:” | “,” | “[” | “]” | “{” | “}”
  && c !== CHAR_MINUS
  && c !== CHAR_QUESTION
  && c !== CHAR_COLON
  && c !== CHAR_COMMA
  && c !== CHAR_LEFT_SQUARE_BRACKET
  && c !== CHAR_RIGHT_SQUARE_BRACKET
  && c !== CHAR_LEFT_CURLY_BRACKET
  && c !== CHAR_RIGHT_CURLY_BRACKET
  // | “#” | “&” | “*” | “!” | “|” | “>” | “'” | “"”
  && c !== CHAR_SHARP
  && c !== CHAR_AMPERSAND
  && c !== CHAR_ASTERISK
  && c !== CHAR_EXCLAMATION
  && c !== CHAR_VERTICAL_LINE
  && c !== CHAR_GREATER_THAN
  && c !== CHAR_SINGLE_QUOTE
  && c !== CHAR_DOUBLE_QUOTE
  // | “%” | “@” | “`”)
  && c !== CHAR_PERCENT
  && c !== CHAR_COMMERCIAL_AT
  && c !== CHAR_GRAVE_ACCENT;

}

// Determines whether block indentation indicator is required. function needIndentIndicator(string) {

var leadingSpaceRe = /^\n* /;
return leadingSpaceRe.test(string);

}

var STYLE_PLAIN = 1,

STYLE_SINGLE  = 2,
STYLE_LITERAL = 3,
STYLE_FOLDED  = 4,
STYLE_DOUBLE  = 5;

// Determines which scalar styles are possible and returns the preferred style. // lineWidth = -1 => no limit. // Pre-conditions: str.length > 0. // Post-conditions: // STYLE_PLAIN or STYLE_SINGLE => no n are in the string. // STYLE_LITERAL => no lines are suitable for folding (or lineWidth is -1). // STYLE_FOLDED => a line > lineWidth and can be folded (and lineWidth != -1). function chooseScalarStyle(string, singleLineOnly, indentPerLevel, lineWidth, testAmbiguousType) {

var i;
var char;
var hasLineBreak = false;
var hasFoldableLine = false; // only checked if shouldTrackWidth
var shouldTrackWidth = lineWidth !== -1;
var previousLineBreak = -1; // count the first line correctly
var plain = isPlainSafeFirst(string.charCodeAt(0))
        && !isWhitespace(string.charCodeAt(string.length - 1));

if (singleLineOnly) {
  // Case: no block styles.
  // Check for disallowed characters to rule out plain and single.
  for (i = 0; i < string.length; i++) {
    char = string.charCodeAt(i);
    if (!isPrintable(char)) {
      return STYLE_DOUBLE;
    }
    plain = plain && isPlainSafe(char);
  }
} else {
  // Case: block styles permitted.
  for (i = 0; i < string.length; i++) {
    char = string.charCodeAt(i);
    if (char === CHAR_LINE_FEED) {
      hasLineBreak = true;
      // Check if any line can be folded.
      if (shouldTrackWidth) {
        hasFoldableLine = hasFoldableLine ||
          // Foldable line = too long, and not more-indented.
          (i - previousLineBreak - 1 > lineWidth &&
           string[previousLineBreak + 1] !== ' ');
        previousLineBreak = i;
      }
    } else if (!isPrintable(char)) {
      return STYLE_DOUBLE;
    }
    plain = plain && isPlainSafe(char);
  }
  // in case the end is missing a \n
  hasFoldableLine = hasFoldableLine || (shouldTrackWidth &&
    (i - previousLineBreak - 1 > lineWidth &&
     string[previousLineBreak + 1] !== ' '));
}
// Although every style can represent \n without escaping, prefer block styles
// for multiline, since they're more readable and they don't add empty lines.
// Also prefer folding a super-long line.
if (!hasLineBreak && !hasFoldableLine) {
  // Strings interpretable as another type have to be quoted;
  // e.g. the string 'true' vs. the boolean true.
  return plain && !testAmbiguousType(string)
    ? STYLE_PLAIN : STYLE_SINGLE;
}
// Edge case: block indentation indicator can only have one digit.
if (indentPerLevel > 9 && needIndentIndicator(string)) {
  return STYLE_DOUBLE;
}
// At this point we know block styles are valid.
// Prefer literal style unless we want to fold.
return hasFoldableLine ? STYLE_FOLDED : STYLE_LITERAL;

}

// Note: line breaking/folding is implemented for only the folded style. // NB. We drop the last trailing newline (if any) of a returned block scalar // since the dumper adds its own newline. This always works: // • No ending newline => unaffected; already using strip “-” chomping. // • Ending newline => removed then restored. // Importantly, this keeps the “+” chomp indicator from gaining an extra line. function writeScalar(state, string, level, iskey) {

state.dump = (function () {
  if (string.length === 0) {
    return "''";
  }
  if (!state.noCompatMode &&
      DEPRECATED_BOOLEANS_SYNTAX.indexOf(string) !== -1) {
    return "'" + string + "'";
  }

  var indent = state.indent * Math.max(1, level); // no 0-indent scalars
  // As indentation gets deeper, let the width decrease monotonically
  // to the lower bound min(state.lineWidth, 40).
  // Note that this implies
  //  state.lineWidth ≤ 40 + state.indent: width is fixed at the lower bound.
  //  state.lineWidth > 40 + state.indent: width decreases until the lower bound.
  // This behaves better than a constant minimum width which disallows narrower options,
  // or an indent threshold which causes the width to suddenly increase.
  var lineWidth = state.lineWidth === -1
    ? -1 : Math.max(Math.min(state.lineWidth, 40), state.lineWidth - indent);

  // Without knowing if keys are implicit/explicit, assume implicit for safety.
  var singleLineOnly = iskey
    // No block styles in flow mode.
    || (state.flowLevel > -1 && level >= state.flowLevel);
  function testAmbiguity(string) {
    return testImplicitResolving(state, string);
  }

  switch (chooseScalarStyle(string, singleLineOnly, state.indent, lineWidth, testAmbiguity)) {
    case STYLE_PLAIN:
      return string;
    case STYLE_SINGLE:
      return "'" + string.replace(/'/g, "''") + "'";
    case STYLE_LITERAL:
      return '|' + blockHeader(string, state.indent)
        + dropEndingNewline(indentString(string, indent));
    case STYLE_FOLDED:
      return '>' + blockHeader(string, state.indent)
        + dropEndingNewline(indentString(foldString(string, lineWidth), indent));
    case STYLE_DOUBLE:
      return '"' + escapeString(string, lineWidth) + '"';
    default:
      throw new YAMLException('impossible error: invalid scalar style');
  }
}());

}

// Pre-conditions: string is valid for a block scalar, 1 <= indentPerLevel <= 9. function blockHeader(string, indentPerLevel) {

var indentIndicator = needIndentIndicator(string) ? String(indentPerLevel) : '';

// note the special case: the string '\n' counts as a "trailing" empty line.
var clip =          string[string.length - 1] === '\n';
var keep = clip && (string[string.length - 2] === '\n' || string === '\n');
var chomp = keep ? '+' : (clip ? '' : '-');

return indentIndicator + chomp + '\n';

}

// (See the note for writeScalar.) function dropEndingNewline(string) {

return string[string.length - 1] === '\n' ? string.slice(0, -1) : string;

}

// Note: a long line without a suitable break point will exceed the width limit. // Pre-conditions: every char in str isPrintable, str.length > 0, width > 0. function foldString(string, width) {

// In folded style, $k$ consecutive newlines output as $k+1$ newlines—
// unless they're before or after a more-indented line, or at the very
// beginning or end, in which case $k$ maps to $k$.
// Therefore, parse each chunk as newline(s) followed by a content line.
var lineRe = /(\n+)([^\n]*)/g;

// first line (possibly an empty line)
var result = (function () {
  var nextLF = string.indexOf('\n');
  nextLF = nextLF !== -1 ? nextLF : string.length;
  lineRe.lastIndex = nextLF;
  return foldLine(string.slice(0, nextLF), width);
}());
// If we haven't reached the first content line yet, don't add an extra \n.
var prevMoreIndented = string[0] === '\n' || string[0] === ' ';
var moreIndented;

// rest of the lines
var match;
while ((match = lineRe.exec(string))) {
  var prefix = match[1], line = match[2];
  moreIndented = (line[0] === ' ');
  result += prefix
    + (!prevMoreIndented && !moreIndented && line !== ''
      ? '\n' : '')
    + foldLine(line, width);
  prevMoreIndented = moreIndented;
}

return result;

}

// Greedy line breaking. // Picks the longest line under the limit each time, // otherwise settles for the shortest line over the limit. // NB. More-indented lines cannot be folded, as that would add an extra n. function foldLine(line, width) {

if (line === '' || line[0] === ' ') return line;

// Since a more-indented line adds a \n, breaks can't be followed by a space.
var breakRe = / [^ ]/g; // note: the match index will always be <= length-2.
var match;
// start is an inclusive index. end, curr, and next are exclusive.
var start = 0, end, curr = 0, next = 0;
var result = '';

// Invariants: 0 <= start <= length-1.
//   0 <= curr <= next <= max(0, length-2). curr - start <= width.
// Inside the loop:
//   A match implies length >= 2, so curr and next are <= length-2.
while ((match = breakRe.exec(line))) {
  next = match.index;
  // maintain invariant: curr - start <= width
  if (next - start > width) {
    end = (curr > start) ? curr : next; // derive end <= length-2
    result += '\n' + line.slice(start, end);
    // skip the space that was output as \n
    start = end + 1;                    // derive start <= length-1
  }
  curr = next;
}

// By the invariants, start <= length-1, so there is something left over.
// It is either the whole string or a part starting from non-whitespace.
result += '\n';
// Insert a break if the remainder is too long and there is a break available.
if (line.length - start > width && curr > start) {
  result += line.slice(start, curr) + '\n' + line.slice(curr + 1);
} else {
  result += line.slice(start);
}

return result.slice(1); // drop extra \n joiner

}

// Escapes a double-quoted string. function escapeString(string) {

var result = '';
var char, nextChar;
var escapeSeq;

for (var i = 0; i < string.length; i++) {
  char = string.charCodeAt(i);
  // Check for surrogate pairs (reference Unicode 3.0 section "3.7 Surrogates").
  if (char >= 0xD800 && char <= 0xDBFF/* high surrogate */) {
    nextChar = string.charCodeAt(i + 1);
    if (nextChar >= 0xDC00 && nextChar <= 0xDFFF/* low surrogate */) {
      // Combine the surrogate pair and store it escaped.
      result += encodeHex((char - 0xD800) * 0x400 + nextChar - 0xDC00 + 0x10000);
      // Advance index one extra since we already used that char here.
      i++; continue;
    }
  }
  escapeSeq = ESCAPE_SEQUENCES[char];
  result += !escapeSeq && isPrintable(char)
    ? string[i]
    : escapeSeq || encodeHex(char);
}

return result;

}

function writeFlowSequence(state, level, object) {

var _result = '',
    _tag    = state.tag,
    index,
    length;

for (index = 0, length = object.length; index < length; index += 1) {
  // Write only valid elements.
  if (writeNode(state, level, object[index], false, false)) {
    if (index !== 0) _result += ',' + (!state.condenseFlow ? ' ' : '');
    _result += state.dump;
  }
}

state.tag = _tag;
state.dump = '[' + _result + ']';

}

function writeBlockSequence(state, level, object, compact) {

var _result = '',
    _tag    = state.tag,
    index,
    length;

for (index = 0, length = object.length; index < length; index += 1) {
  // Write only valid elements.
  if (writeNode(state, level + 1, object[index], true, true)) {
    if (!compact || index !== 0) {
      _result += generateNextLine(state, level);
    }

    if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
      _result += '-';
    } else {
      _result += '- ';
    }

    _result += state.dump;
  }
}

state.tag = _tag;
state.dump = _result || '[]'; // Empty sequence if no valid values.

}

function writeFlowMapping(state, level, object) {

var _result       = '',
    _tag          = state.tag,
    objectKeyList = Object.keys(object),
    index,
    length,
    objectKey,
    objectValue,
    pairBuffer;

for (index = 0, length = objectKeyList.length; index < length; index += 1) {
  pairBuffer = state.condenseFlow ? '"' : '';

  if (index !== 0) pairBuffer += ', ';

  objectKey = objectKeyList[index];
  objectValue = object[objectKey];

  if (!writeNode(state, level, objectKey, false, false)) {
    continue; // Skip this pair because of invalid key;
  }

  if (state.dump.length > 1024) pairBuffer += '? ';

  pairBuffer += state.dump + (state.condenseFlow ? '"' : '') + ':' + (state.condenseFlow ? '' : ' ');

  if (!writeNode(state, level, objectValue, false, false)) {
    continue; // Skip this pair because of invalid value.
  }

  pairBuffer += state.dump;

  // Both key and value are valid.
  _result += pairBuffer;
}

state.tag = _tag;
state.dump = '{' + _result + '}';

}

function writeBlockMapping(state, level, object, compact) {

var _result       = '',
    _tag          = state.tag,
    objectKeyList = Object.keys(object),
    index,
    length,
    objectKey,
    objectValue,
    explicitPair,
    pairBuffer;

// Allow sorting keys so that the output file is deterministic
if (state.sortKeys === true) {
  // Default sorting
  objectKeyList.sort();
} else if (typeof state.sortKeys === 'function') {
  // Custom sort function
  objectKeyList.sort(state.sortKeys);
} else if (state.sortKeys) {
  // Something is wrong
  throw new YAMLException('sortKeys must be a boolean or a function');
}

for (index = 0, length = objectKeyList.length; index < length; index += 1) {
  pairBuffer = '';

  if (!compact || index !== 0) {
    pairBuffer += generateNextLine(state, level);
  }

  objectKey = objectKeyList[index];
  objectValue = object[objectKey];

  if (!writeNode(state, level + 1, objectKey, true, true, true)) {
    continue; // Skip this pair because of invalid key.
  }

  explicitPair = (state.tag !== null && state.tag !== '?') ||
                 (state.dump && state.dump.length > 1024);

  if (explicitPair) {
    if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
      pairBuffer += '?';
    } else {
      pairBuffer += '? ';
    }
  }

  pairBuffer += state.dump;

  if (explicitPair) {
    pairBuffer += generateNextLine(state, level);
  }

  if (!writeNode(state, level + 1, objectValue, true, explicitPair)) {
    continue; // Skip this pair because of invalid value.
  }

  if (state.dump && CHAR_LINE_FEED === state.dump.charCodeAt(0)) {
    pairBuffer += ':';
  } else {
    pairBuffer += ': ';
  }

  pairBuffer += state.dump;

  // Both key and value are valid.
  _result += pairBuffer;
}

state.tag = _tag;
state.dump = _result || '{}'; // Empty mapping if no valid pairs.

}

function detectType(state, object, explicit) {

var _result, typeList, index, length, type, style;

typeList = explicit ? state.explicitTypes : state.implicitTypes;

for (index = 0, length = typeList.length; index < length; index += 1) {
  type = typeList[index];

  if ((type.instanceOf  || type.predicate) &&
      (!type.instanceOf || ((typeof object === 'object') && (object instanceof type.instanceOf))) &&
      (!type.predicate  || type.predicate(object))) {

    state.tag = explicit ? type.tag : '?';

    if (type.represent) {
      style = state.styleMap[type.tag] || type.defaultStyle;

      if (_toString.call(type.represent) === '[object Function]') {
        _result = type.represent(object, style);
      } else if (_hasOwnProperty.call(type.represent, style)) {
        _result = type.represent[style](object, style);
      } else {
        throw new YAMLException('!<' + type.tag + '> tag resolver accepts not "' + style + '" style');
      }

      state.dump = _result;
    }

    return true;
  }
}

return false;

}

// Serializes `object` and writes it to global `result`. // Returns true on success, or false on invalid object. // function writeNode(state, level, object, block, compact, iskey) {

state.tag = null;
state.dump = object;

if (!detectType(state, object, false)) {
  detectType(state, object, true);
}

var type = _toString.call(state.dump);

if (block) {
  block = (state.flowLevel < 0 || state.flowLevel > level);
}

var objectOrArray = type === '[object Object]' || type === '[object Array]',
    duplicateIndex,
    duplicate;

if (objectOrArray) {
  duplicateIndex = state.duplicates.indexOf(object);
  duplicate = duplicateIndex !== -1;
}

if ((state.tag !== null && state.tag !== '?') || duplicate || (state.indent !== 2 && level > 0)) {
  compact = false;
}

if (duplicate && state.usedDuplicates[duplicateIndex]) {
  state.dump = '*ref_' + duplicateIndex;
} else {
  if (objectOrArray && duplicate && !state.usedDuplicates[duplicateIndex]) {
    state.usedDuplicates[duplicateIndex] = true;
  }
  if (type === '[object Object]') {
    if (block && (Object.keys(state.dump).length !== 0)) {
      writeBlockMapping(state, level, state.dump, compact);
      if (duplicate) {
        state.dump = '&ref_' + duplicateIndex + state.dump;
      }
    } else {
      writeFlowMapping(state, level, state.dump);
      if (duplicate) {
        state.dump = '&ref_' + duplicateIndex + ' ' + state.dump;
      }
    }
  } else if (type === '[object Array]') {
    var arrayLevel = (state.noArrayIndent && (level > 0)) ? level - 1 : level;
    if (block && (state.dump.length !== 0)) {
      writeBlockSequence(state, arrayLevel, state.dump, compact);
      if (duplicate) {
        state.dump = '&ref_' + duplicateIndex + state.dump;
      }
    } else {
      writeFlowSequence(state, arrayLevel, state.dump);
      if (duplicate) {
        state.dump = '&ref_' + duplicateIndex + ' ' + state.dump;
      }
    }
  } else if (type === '[object String]') {
    if (state.tag !== '?') {
      writeScalar(state, state.dump, level, iskey);
    }
  } else {
    if (state.skipInvalid) return false;
    throw new YAMLException('unacceptable kind of an object to dump ' + type);
  }

  if (state.tag !== null && state.tag !== '?') {
    state.dump = '!<' + state.tag + '> ' + state.dump;
  }
}

return true;

}

function getDuplicateReferences(object, state) {

var objects = [],
    duplicatesIndexes = [],
    index,
    length;

inspectNode(object, objects, duplicatesIndexes);

for (index = 0, length = duplicatesIndexes.length; index < length; index += 1) {
  state.duplicates.push(objects[duplicatesIndexes[index]]);
}
state.usedDuplicates = new Array(length);

}

function inspectNode(object, objects, duplicatesIndexes) {

var objectKeyList,
    index,
    length;

if (object !== null && typeof object === 'object') {
  index = objects.indexOf(object);
  if (index !== -1) {
    if (duplicatesIndexes.indexOf(index) === -1) {
      duplicatesIndexes.push(index);
    }
  } else {
    objects.push(object);

    if (Array.isArray(object)) {
      for (index = 0, length = object.length; index < length; index += 1) {
        inspectNode(object[index], objects, duplicatesIndexes);
      }
    } else {
      objectKeyList = Object.keys(object);

      for (index = 0, length = objectKeyList.length; index < length; index += 1) {
        inspectNode(object[objectKeyList[index]], objects, duplicatesIndexes);
      }
    }
  }
}

}

function dump(input, options) {

options = options || {};

var state = new State(options);

if (!state.noRefs) getDuplicateReferences(input, state);

if (writeNode(state, 0, input, true, true)) return state.dump + '\n';

return '';

}

function safeDump(input, options) {

return dump(input, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));

}

module.exports.dump = dump; module.exports.safeDump = safeDump;