l0bsterssg

dumper.js (27488B)

---

 '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_CARRIAGE_RETURN      = 0x0D; /* CR */
 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_EQUALS               = 0x3D; /* = */
 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[0x00]   = '\\0';
 ESCAPE_SEQUENCES[0x07]   = '\\a';
 ESCAPE_SEQUENCES[0x08]   = '\\b';
 ESCAPE_SEQUENCES[0x09]   = '\\t';
 ESCAPE_SEQUENCES[0x0A]   = '\\n';
 ESCAPE_SEQUENCES[0x0B]   = '\\v';
 ESCAPE_SEQUENCES[0x0C]   = '\\f';
 ESCAPE_SEQUENCES[0x0D]   = '\\r';
 ESCAPE_SEQUENCES[0x1B]   = '\\e';
 ESCAPE_SEQUENCES[0x22]   = '\\"';
 ESCAPE_SEQUENCES[0x5C]   = '\\\\';
 ESCAPE_SEQUENCES[0x85]   = '\\N';
 ESCAPE_SEQUENCES[0xA0]   = '\\_';
 ESCAPE_SEQUENCES[0x2028] = '\\L';
 ESCAPE_SEQUENCES[0x2029] = '\\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(c) {
   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(c) {
   return  (0x00020 <= c && c <= 0x00007E)
       || ((0x000A1 <= c && c <= 0x00D7FF) && c !== 0x2028 && c !== 0x2029)
       || ((0x0E000 <= c && c <= 0x00FFFD) && c !== 0xFEFF /* BOM */)
       ||  (0x10000 <= c && c <= 0x10FFFF);
 }
 
 // [34] ns-char ::= nb-char - s-white
 // [27] nb-char ::= c-printable - b-char - c-byte-order-mark
 // [26] b-char  ::= b-line-feed | b-carriage-return
 // [24] b-line-feed       ::=     #xA    /* LF */
 // [25] b-carriage-return ::=     #xD    /* CR */
 // [3]  c-byte-order-mark ::=     #xFEFF
 function isNsChar(c) {
   return isPrintable(c) && !isWhitespace(c)
     // byte-order-mark
     && c !== 0xFEFF
     // b-char
     && c !== CHAR_CARRIAGE_RETURN
     && c !== CHAR_LINE_FEED;
 }
 
 // Simplified test for values allowed after the first character in plain style.
 function isPlainSafe(c, prev) {
   // 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
     // - ":" - "#"
     // /* An ns-char preceding */ "#"
     && c !== CHAR_COLON
     && ((c !== CHAR_SHARP) || (prev && isNsChar(prev)));
 }
 
 // Simplified test for values allowed as the first character in plain style.
 function isPlainSafeFirst(c) {
   // 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_EQUALS
     && 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, prev_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;
       }
       prev_char = i > 0 ? string.charCodeAt(i - 1) : null;
       plain = plain && isPlainSafe(char, prev_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;
       }
       prev_char = i > 0 ? string.charCodeAt(i - 1) : null;
       plain = plain && isPlainSafe(char, prev_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 = '';
     if (index !== 0) pairBuffer += ', ';
 
     if (state.condenseFlow) 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;