text: 'use strict';
  
  /*eslint-disable max-len,no-use-before-define*/
  
  var common              = require('./common');
  var YAMLException       = require('./exception');
  var Mark                = require('./mark');
  var DEFAULT_SAFE_SCHEMA = require('./schema/default_safe');
  var DEFAULT_FULL_SCHEMA = require('./schema/default_full');
  
  
  var _hasOwnProperty = Object.prototype.hasOwnProperty;
  
  
  var CONTEXT_FLOW_IN   = 1;
  var CONTEXT_FLOW_OUT  = 2;
  var CONTEXT_BLOCK_IN  = 3;
  var CONTEXT_BLOCK_OUT = 4;
  
  
  var CHOMPING_CLIP  = 1;
  var CHOMPING_STRIP = 2;
  var CHOMPING_KEEP  = 3;
  
  
  var PATTERN_NON_PRINTABLE         = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\x84\x86-\x9F\uFFFE\uFFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF]/;
  var PATTERN_NON_ASCII_LINE_BREAKS = /[\x85\u2028\u2029]/;
  var PATTERN_FLOW_INDICATORS       = /[,\[\]\{\}]/;
  var PATTERN_TAG_HANDLE            = /^(?:!|!!|![a-z\-]+!)$/i;
  var PATTERN_TAG_URI               = /^(?:!|[^,\[\]\{\}])(?:%[0-9a-f]{2}|[0-9a-z\-#;\/\?:@&=\+\$,_\.!~\*'\(\)\[\]])*$/i;
  
  
  function _class(obj) { return Object.prototype.toString.call(obj); }
  
  function is_EOL(c) {
    return (c === 0x0A/* LF */) || (c === 0x0D/* CR */);
  }
  
  function is_WHITE_SPACE(c) {
    return (c === 0x09/* Tab */) || (c === 0x20/* Space */);
  }
  
  function is_WS_OR_EOL(c) {
    return (c === 0x09/* Tab */) ||
           (c === 0x20/* Space */) ||
           (c === 0x0A/* LF */) ||
           (c === 0x0D/* CR */);
  }
  
  function is_FLOW_INDICATOR(c) {
    return c === 0x2C/* , */ ||
           c === 0x5B/* [ */ ||
           c === 0x5D/* ] */ ||
           c === 0x7B/* { */ ||
           c === 0x7D/* } */;
  }
  
  function fromHexCode(c) {
    var lc;
  
    if ((0x30/* 0 */ <= c) && (c <= 0x39/* 9 */)) {
      return c - 0x30;
    }
  
    /*eslint-disable no-bitwise*/
    lc = c | 0x20;
  
    if ((0x61/* a */ <= lc) && (lc <= 0x66/* f */)) {
      return lc - 0x61 + 10;
    }
  
    return -1;
  }
  
  function escapedHexLen(c) {
    if (c === 0x78/* x */) { return 2; }
    if (c === 0x75/* u */) { return 4; }
    if (c === 0x55/* U */) { return 8; }
    return 0;
  }
  
  function fromDecimalCode(c) {
    if ((0x30/* 0 */ <= c) && (c <= 0x39/* 9 */)) {
      return c - 0x30;
    }
  
    return -1;
  }
  
  function simpleEscapeSequence(c) {
    /* eslint-disable indent */
    return (c === 0x30/* 0 */) ? '\x00' :
          (c === 0x61/* a */) ? '\x07' :
          (c === 0x62/* b */) ? '\x08' :
          (c === 0x74/* t */) ? '\x09' :
          (c === 0x09/* Tab */) ? '\x09' :
          (c === 0x6E/* n */) ? '\x0A' :
          (c === 0x76/* v */) ? '\x0B' :
          (c === 0x66/* f */) ? '\x0C' :
          (c === 0x72/* r */) ? '\x0D' :
          (c === 0x65/* e */) ? '\x1B' :
          (c === 0x20/* Space */) ? ' ' :
          (c === 0x22/* " */) ? '\x22' :
          (c === 0x2F/* / */) ? '/' :
          (c === 0x5C/* \ */) ? '\x5C' :
          (c === 0x4E/* N */) ? '\x85' :
          (c === 0x5F/* _ */) ? '\xA0' :
          (c === 0x4C/* L */) ? '\u2028' :
          (c === 0x50/* P */) ? '\u2029' : '';
  }
  
  function charFromCodepoint(c) {
    if (c <= 0xFFFF) {
      return String.fromCharCode(c);
    }
    // Encode UTF-16 surrogate pair
    // https://en.wikipedia.org/wiki/UTF-16#Code_points_U.2B010000_to_U.2B10FFFF
    return String.fromCharCode(
      ((c - 0x010000) >> 10) + 0xD800,
      ((c - 0x010000) & 0x03FF) + 0xDC00
    );
  }
  
  var simpleEscapeCheck = new Array(256); // integer, for fast access
  var simpleEscapeMap = new Array(256);
  for (var i = 0; i < 256; i++) {
    simpleEscapeCheck[i] = simpleEscapeSequence(i) ? 1 : 0;
    simpleEscapeMap[i] = simpleEscapeSequence(i);
  }
  
  
  function State(input, options) {
    this.input = input;
  
    this.filename  = options['filename']  || null;
    this.schema    = options['schema']    || DEFAULT_FULL_SCHEMA;
    this.onWarning = options['onWarning'] || null;
    this.legacy    = options['legacy']    || false;
    this.json      = options['json']      || false;
    this.listener  = options['listener']  || null;
  
    this.implicitTypes = this.schema.compiledImplicit;
    this.typeMap       = this.schema.compiledTypeMap;
  
    this.length     = input.length;
    this.position   = 0;
    this.line       = 0;
    this.lineStart  = 0;
    this.lineIndent = 0;
  
    this.documents = [];
  
    /*
    this.version;
    this.checkLineBreaks;
    this.tagMap;
    this.anchorMap;
    this.tag;
    this.anchor;
    this.kind;
    this.result;*/
  
  }
  
  
  function generateError(state, message) {
    return new YAMLException(
      message,
      new Mark(state.filename, state.input, state.position, state.line, (state.position - state.lineStart)));
  }
  
  function throwError(state, message) {
    throw generateError(state, message);
  }
  
  function throwWarning(state, message) {
    if (state.onWarning) {
      state.onWarning.call(null, generateError(state, message));
    }
  }
  
  
  var directiveHandlers = {
  
    YAML: function handleYamlDirective(state, name, args) {
  
      var match, major, minor;
  
      if (state.version !== null) {
        throwError(state, 'duplication of %YAML directive');
      }
  
      if (args.length !== 1) {
        throwError(state, 'YAML directive accepts exactly one argument');
      }
  
      match = /^([0-9]+)\.([0-9]+)$/.exec(args[0]);
  
      if (match === null) {
        throwError(state, 'ill-formed argument of the YAML directive');
      }
  
      major = parseInt(match[1], 10);
      minor = parseInt(match[2], 10);
  
      if (major !== 1) {
        throwError(state, 'unacceptable YAML version of the document');
      }
  
      state.version = args[0];
      state.checkLineBreaks = (minor < 2);
  
      if (minor !== 1 && minor !== 2) {
        throwWarning(state, 'unsupported YAML version of the document');
      }
    },
  
    TAG: function handleTagDirective(state, name, args) {
  
      var handle, prefix;
  
      if (args.length !== 2) {
        throwError(state, 'TAG directive accepts exactly two arguments');
      }
  
      handle = args[0];
      prefix = args[1];
  
      if (!PATTERN_TAG_HANDLE.test(handle)) {
        throwError(state, 'ill-formed tag handle (first argument) of the TAG directive');
      }
  
      if (_hasOwnProperty.call(state.tagMap, handle)) {
        throwError(state, 'there is a previously declared suffix for "' + handle + '" tag handle');
      }
  
      if (!PATTERN_TAG_URI.test(prefix)) {
        throwError(state, 'ill-formed tag prefix (second argument) of the TAG directive');
      }
  
      state.tagMap[handle] = prefix;
    }
  };
  
  
  function captureSegment(state, start, end, checkJson) {
    var _position, _length, _character, _result;
  
    if (start < end) {
      _result = state.input.slice(start, end);
  
      if (checkJson) {
        for (_position = 0, _length = _result.length; _position < _length; _position += 1) {
          _character = _result.charCodeAt(_position);
          if (!(_character === 0x09 ||
                (0x20 <= _character && _character <= 0x10FFFF))) {
            throwError(state, 'expected valid JSON character');
          }
        }
      } else if (PATTERN_NON_PRINTABLE.test(_result)) {
        throwError(state, 'the stream contains non-printable characters');
      }
  
      state.result += _result;
    }
  }
  
  function mergeMappings(state, destination, source, overridableKeys) {
    var sourceKeys, key, index, quantity;
  
    if (!common.isObject(source)) {
      throwError(state, 'cannot merge mappings; the provided source object is unacceptable');
    }
  
    sourceKeys = Object.keys(source);
  
    for (index = 0, quantity = sourceKeys.length; index < quantity; index += 1) {
      key = sourceKeys[index];
  
      if (!_hasOwnProperty.call(destination, key)) {
        destination[key] = source[key];
        overridableKeys[key] = true;
      }
    }
  }
  
  function storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode, startLine, startPos) {
    var index, quantity;
  
    // The output is a plain object here, so keys can only be strings.
    // We need to convert keyNode to a string, but doing so can hang the process
    // (deeply nested arrays that explode exponentially using aliases).
    if (Array.isArray(keyNode)) {
      keyNode = Array.prototype.slice.call(keyNode);
  
      for (index = 0, quantity = keyNode.length; index < quantity; index += 1) {
        if (Array.isArray(keyNode[index])) {
          throwError(state, 'nested arrays are not supported inside keys');
        }
  
        if (typeof keyNode === 'object' && _class(keyNode[index]) === '[object Object]') {
          keyNode[index] = '[object Object]';
        }
      }
    }
  
    // Avoid code execution in load() via toString property
    // (still use its own toString for arrays, timestamps,
    // and whatever user schema extensions happen to have @@toStringTag)
    if (typeof keyNode === 'object' && _class(keyNode) === '[object Object]') {
      keyNode = '[object Object]';
    }
  
  
    keyNode = String(keyNode);
  
    if (_result === null) {
      _result = {};
    }
  
    if (keyTag === 'tag:yaml.org,2002:merge') {
      if (Array.isArray(valueNode)) {
        for (index = 0, quantity = valueNode.length; index < quantity; index += 1) {
          mergeMappings(state, _result, valueNode[index], overridableKeys);
        }
      } else {
        mergeMappings(state, _result, valueNode, overridableKeys);
      }
    } else {
      if (!state.json &&
          !_hasOwnProperty.call(overridableKeys, keyNode) &&
          _hasOwnProperty.call(_result, keyNode)) {
        state.line = startLine || state.line;
        state.position = startPos || state.position;
        throwError(state, 'duplicated mapping key');
      }
      _result[keyNode] = valueNode;
      delete overridableKeys[keyNode];
    }
  
    return _result;
  }
  
  function readLineBreak(state) {
    var ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch === 0x0A/* LF */) {
      state.position++;
    } else if (ch === 0x0D/* CR */) {
      state.position++;
      if (state.input.charCodeAt(state.position) === 0x0A/* LF */) {
        state.position++;
      }
    } else {
      throwError(state, 'a line break is expected');
    }
  
    state.line += 1;
    state.lineStart = state.position;
  }
  
  function skipSeparationSpace(state, allowComments, checkIndent) {
    var lineBreaks = 0,
        ch = state.input.charCodeAt(state.position);
  
    while (ch !== 0) {
      while (is_WHITE_SPACE(ch)) {
        ch = state.input.charCodeAt(++state.position);
      }
  
      if (allowComments && ch === 0x23/* # */) {
        do {
          ch = state.input.charCodeAt(++state.position);
        } while (ch !== 0x0A/* LF */ && ch !== 0x0D/* CR */ && ch !== 0);
      }
  
      if (is_EOL(ch)) {
        readLineBreak(state);
  
        ch = state.input.charCodeAt(state.position);
        lineBreaks++;
        state.lineIndent = 0;
  
        while (ch === 0x20/* Space */) {
          state.lineIndent++;
          ch = state.input.charCodeAt(++state.position);
        }
      } else {
        break;
      }
    }
  
    if (checkIndent !== -1 && lineBreaks !== 0 && state.lineIndent < checkIndent) {
      throwWarning(state, 'deficient indentation');
    }
  
    return lineBreaks;
  }
  
  function testDocumentSeparator(state) {
    var _position = state.position,
        ch;
  
    ch = state.input.charCodeAt(_position);
  
    // Condition state.position === state.lineStart is tested
    // in parent on each call, for efficiency. No needs to test here again.
    if ((ch === 0x2D/* - */ || ch === 0x2E/* . */) &&
        ch === state.input.charCodeAt(_position + 1) &&
        ch === state.input.charCodeAt(_position + 2)) {
  
      _position += 3;
  
      ch = state.input.charCodeAt(_position);
  
      if (ch === 0 || is_WS_OR_EOL(ch)) {
        return true;
      }
    }
  
    return false;
  }
  
  function writeFoldedLines(state, count) {
    if (count === 1) {
      state.result += ' ';
    } else if (count > 1) {
      state.result += common.repeat('\n', count - 1);
    }
  }
  
  
  function readPlainScalar(state, nodeIndent, withinFlowCollection) {
    var preceding,
        following,
        captureStart,
        captureEnd,
        hasPendingContent,
        _line,
        _lineStart,
        _lineIndent,
        _kind = state.kind,
        _result = state.result,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (is_WS_OR_EOL(ch)      ||
        is_FLOW_INDICATOR(ch) ||
        ch === 0x23/* # */    ||
        ch === 0x26/* & */    ||
        ch === 0x2A/* * */    ||
        ch === 0x21/* ! */    ||
        ch === 0x7C/* | */    ||
        ch === 0x3E/* > */    ||
        ch === 0x27/* ' */    ||
        ch === 0x22/* " */    ||
        ch === 0x25/* % */    ||
        ch === 0x40/* @ */    ||
        ch === 0x60/* ` */) {
      return false;
    }
  
    if (ch === 0x3F/* ? */ || ch === 0x2D/* - */) {
      following = state.input.charCodeAt(state.position + 1);
  
      if (is_WS_OR_EOL(following) ||
          withinFlowCollection && is_FLOW_INDICATOR(following)) {
        return false;
      }
    }
  
    state.kind = 'scalar';
    state.result = '';
    captureStart = captureEnd = state.position;
    hasPendingContent = false;
  
    while (ch !== 0) {
      if (ch === 0x3A/* : */) {
        following = state.input.charCodeAt(state.position + 1);
  
        if (is_WS_OR_EOL(following) ||
            withinFlowCollection && is_FLOW_INDICATOR(following)) {
          break;
        }
  
      } else if (ch === 0x23/* # */) {
        preceding = state.input.charCodeAt(state.position - 1);
  
        if (is_WS_OR_EOL(preceding)) {
          break;
        }
  
      } else if ((state.position === state.lineStart && testDocumentSeparator(state)) ||
                 withinFlowCollection && is_FLOW_INDICATOR(ch)) {
        break;
  
      } else if (is_EOL(ch)) {
        _line = state.line;
        _lineStart = state.lineStart;
        _lineIndent = state.lineIndent;
        skipSeparationSpace(state, false, -1);
  
        if (state.lineIndent >= nodeIndent) {
          hasPendingContent = true;
          ch = state.input.charCodeAt(state.position);
          continue;
        } else {
          state.position = captureEnd;
          state.line = _line;
          state.lineStart = _lineStart;
          state.lineIndent = _lineIndent;
          break;
        }
      }
  
      if (hasPendingContent) {
        captureSegment(state, captureStart, captureEnd, false);
        writeFoldedLines(state, state.line - _line);
        captureStart = captureEnd = state.position;
        hasPendingContent = false;
      }
  
      if (!is_WHITE_SPACE(ch)) {
        captureEnd = state.position + 1;
      }
  
      ch = state.input.charCodeAt(++state.position);
    }
  
    captureSegment(state, captureStart, captureEnd, false);
  
    if (state.result) {
      return true;
    }
  
    state.kind = _kind;
    state.result = _result;
    return false;
  }
  
  function readSingleQuotedScalar(state, nodeIndent) {
    var ch,
        captureStart, captureEnd;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch !== 0x27/* ' */) {
      return false;
    }
  
    state.kind = 'scalar';
    state.result = '';
    state.position++;
    captureStart = captureEnd = state.position;
  
    while ((ch = state.input.charCodeAt(state.position)) !== 0) {
      if (ch === 0x27/* ' */) {
        captureSegment(state, captureStart, state.position, true);
        ch = state.input.charCodeAt(++state.position);
  
        if (ch === 0x27/* ' */) {
          captureStart = state.position;
          state.position++;
          captureEnd = state.position;
        } else {
          return true;
        }
  
      } else if (is_EOL(ch)) {
        captureSegment(state, captureStart, captureEnd, true);
        writeFoldedLines(state, skipSeparationSpace(state, false, nodeIndent));
        captureStart = captureEnd = state.position;
  
      } else if (state.position === state.lineStart && testDocumentSeparator(state)) {
        throwError(state, 'unexpected end of the document within a single quoted scalar');
  
      } else {
        state.position++;
        captureEnd = state.position;
      }
    }
  
    throwError(state, 'unexpected end of the stream within a single quoted scalar');
  }
  
  function readDoubleQuotedScalar(state, nodeIndent) {
    var captureStart,
        captureEnd,
        hexLength,
        hexResult,
        tmp,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch !== 0x22/* " */) {
      return false;
    }
  
    state.kind = 'scalar';
    state.result = '';
    state.position++;
    captureStart = captureEnd = state.position;
  
    while ((ch = state.input.charCodeAt(state.position)) !== 0) {
      if (ch === 0x22/* " */) {
        captureSegment(state, captureStart, state.position, true);
        state.position++;
        return true;
  
      } else if (ch === 0x5C/* \ */) {
        captureSegment(state, captureStart, state.position, true);
        ch = state.input.charCodeAt(++state.position);
  
        if (is_EOL(ch)) {
          skipSeparationSpace(state, false, nodeIndent);
  
          // TODO: rework to inline fn with no type cast?
        } else if (ch < 256 && simpleEscapeCheck[ch]) {
          state.result += simpleEscapeMap[ch];
          state.position++;
  
        } else if ((tmp = escapedHexLen(ch)) > 0) {
          hexLength = tmp;
          hexResult = 0;
  
          for (; hexLength > 0; hexLength--) {
            ch = state.input.charCodeAt(++state.position);
  
            if ((tmp = fromHexCode(ch)) >= 0) {
              hexResult = (hexResult << 4) + tmp;
  
            } else {
              throwError(state, 'expected hexadecimal character');
            }
          }
  
          state.result += charFromCodepoint(hexResult);
  
          state.position++;
  
        } else {
          throwError(state, 'unknown escape sequence');
        }
  
        captureStart = captureEnd = state.position;
  
      } else if (is_EOL(ch)) {
        captureSegment(state, captureStart, captureEnd, true);
        writeFoldedLines(state, skipSeparationSpace(state, false, nodeIndent));
        captureStart = captureEnd = state.position;
  
      } else if (state.position === state.lineStart && testDocumentSeparator(state)) {
        throwError(state, 'unexpected end of the document within a double quoted scalar');
  
      } else {
        state.position++;
        captureEnd = state.position;
      }
    }
  
    throwError(state, 'unexpected end of the stream within a double quoted scalar');
  }
  
  function readFlowCollection(state, nodeIndent) {
    var readNext = true,
        _line,
        _tag     = state.tag,
        _result,
        _anchor  = state.anchor,
        following,
        terminator,
        isPair,
        isExplicitPair,
        isMapping,
        overridableKeys = {},
        keyNode,
        keyTag,
        valueNode,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch === 0x5B/* [ */) {
      terminator = 0x5D;/* ] */
      isMapping = false;
      _result = [];
    } else if (ch === 0x7B/* { */) {
      terminator = 0x7D;/* } */
      isMapping = true;
      _result = {};
    } else {
      return false;
    }
  
    if (state.anchor !== null) {
      state.anchorMap[state.anchor] = _result;
    }
  
    ch = state.input.charCodeAt(++state.position);
  
    while (ch !== 0) {
      skipSeparationSpace(state, true, nodeIndent);
  
      ch = state.input.charCodeAt(state.position);
  
      if (ch === terminator) {
        state.position++;
        state.tag = _tag;
        state.anchor = _anchor;
        state.kind = isMapping ? 'mapping' : 'sequence';
        state.result = _result;
        return true;
      } else if (!readNext) {
        throwError(state, 'missed comma between flow collection entries');
      }
  
      keyTag = keyNode = valueNode = null;
      isPair = isExplicitPair = false;
  
      if (ch === 0x3F/* ? */) {
        following = state.input.charCodeAt(state.position + 1);
  
        if (is_WS_OR_EOL(following)) {
          isPair = isExplicitPair = true;
          state.position++;
          skipSeparationSpace(state, true, nodeIndent);
        }
      }
  
      _line = state.line;
      composeNode(state, nodeIndent, CONTEXT_FLOW_IN, false, true);
      keyTag = state.tag;
      keyNode = state.result;
      skipSeparationSpace(state, true, nodeIndent);
  
      ch = state.input.charCodeAt(state.position);
  
      if ((isExplicitPair || state.line === _line) && ch === 0x3A/* : */) {
        isPair = true;
        ch = state.input.charCodeAt(++state.position);
        skipSeparationSpace(state, true, nodeIndent);
        composeNode(state, nodeIndent, CONTEXT_FLOW_IN, false, true);
        valueNode = state.result;
      }
  
      if (isMapping) {
        storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode);
      } else if (isPair) {
        _result.push(storeMappingPair(state, null, overridableKeys, keyTag, keyNode, valueNode));
      } else {
        _result.push(keyNode);
      }
  
      skipSeparationSpace(state, true, nodeIndent);
  
      ch = state.input.charCodeAt(state.position);
  
      if (ch === 0x2C/* , */) {
        readNext = true;
        ch = state.input.charCodeAt(++state.position);
      } else {
        readNext = false;
      }
    }
  
    throwError(state, 'unexpected end of the stream within a flow collection');
  }
  
  function readBlockScalar(state, nodeIndent) {
    var captureStart,
        folding,
        chomping       = CHOMPING_CLIP,
        didReadContent = false,
        detectedIndent = false,
        textIndent     = nodeIndent,
        emptyLines     = 0,
        atMoreIndented = false,
        tmp,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch === 0x7C/* | */) {
      folding = false;
    } else if (ch === 0x3E/* > */) {
      folding = true;
    } else {
      return false;
    }
  
    state.kind = 'scalar';
    state.result = '';
  
    while (ch !== 0) {
      ch = state.input.charCodeAt(++state.position);
  
      if (ch === 0x2B/* + */ || ch === 0x2D/* - */) {
        if (CHOMPING_CLIP === chomping) {
          chomping = (ch === 0x2B/* + */) ? CHOMPING_KEEP : CHOMPING_STRIP;
        } else {
          throwError(state, 'repeat of a chomping mode identifier');
        }
  
      } else if ((tmp = fromDecimalCode(ch)) >= 0) {
        if (tmp === 0) {
          throwError(state, 'bad explicit indentation width of a block scalar; it cannot be less than one');
        } else if (!detectedIndent) {
          textIndent = nodeIndent + tmp - 1;
          detectedIndent = true;
        } else {
          throwError(state, 'repeat of an indentation width identifier');
        }
  
      } else {
        break;
      }
    }
  
    if (is_WHITE_SPACE(ch)) {
      do { ch = state.input.charCodeAt(++state.position); }
      while (is_WHITE_SPACE(ch));
  
      if (ch === 0x23/* # */) {
        do { ch = state.input.charCodeAt(++state.position); }
        while (!is_EOL(ch) && (ch !== 0));
      }
    }
  
    while (ch !== 0) {
      readLineBreak(state);
      state.lineIndent = 0;
  
      ch = state.input.charCodeAt(state.position);
  
      while ((!detectedIndent || state.lineIndent < textIndent) &&
             (ch === 0x20/* Space */)) {
        state.lineIndent++;
        ch = state.input.charCodeAt(++state.position);
      }
  
      if (!detectedIndent && state.lineIndent > textIndent) {
        textIndent = state.lineIndent;
      }
  
      if (is_EOL(ch)) {
        emptyLines++;
        continue;
      }
  
      // End of the scalar.
      if (state.lineIndent < textIndent) {
  
        // Perform the chomping.
        if (chomping === CHOMPING_KEEP) {
          state.result += common.repeat('\n', didReadContent ? 1 + emptyLines : emptyLines);
        } else if (chomping === CHOMPING_CLIP) {
          if (didReadContent) { // i.e. only if the scalar is not empty.
            state.result += '\n';
          }
        }
  
        // Break this `while` cycle and go to the funciton's epilogue.
        break;
      }
  
      // Folded style: use fancy rules to handle line breaks.
      if (folding) {
  
        // Lines starting with white space characters (more-indented lines) are not folded.
        if (is_WHITE_SPACE(ch)) {
          atMoreIndented = true;
          // except for the first content line (cf. Example 8.1)
          state.result += common.repeat('\n', didReadContent ? 1 + emptyLines : emptyLines);
  
        // End of more-indented block.
        } else if (atMoreIndented) {
          atMoreIndented = false;
          state.result += common.repeat('\n', emptyLines + 1);
  
        // Just one line break - perceive as the same line.
        } else if (emptyLines === 0) {
          if (didReadContent) { // i.e. only if we have already read some scalar content.
            state.result += ' ';
          }
  
        // Several line breaks - perceive as different lines.
        } else {
          state.result += common.repeat('\n', emptyLines);
        }
  
      // Literal style: just add exact number of line breaks between content lines.
      } else {
        // Keep all line breaks except the header line break.
        state.result += common.repeat('\n', didReadContent ? 1 + emptyLines : emptyLines);
      }
  
      didReadContent = true;
      detectedIndent = true;
      emptyLines = 0;
      captureStart = state.position;
  
      while (!is_EOL(ch) && (ch !== 0)) {
        ch = state.input.charCodeAt(++state.position);
      }
  
      captureSegment(state, captureStart, state.position, false);
    }
  
    return true;
  }
  
  function readBlockSequence(state, nodeIndent) {
    var _line,
        _tag      = state.tag,
        _anchor   = state.anchor,
        _result   = [],
        following,
        detected  = false,
        ch;
  
    if (state.anchor !== null) {
      state.anchorMap[state.anchor] = _result;
    }
  
    ch = state.input.charCodeAt(state.position);
  
    while (ch !== 0) {
  
      if (ch !== 0x2D/* - */) {
        break;
      }
  
      following = state.input.charCodeAt(state.position + 1);
  
      if (!is_WS_OR_EOL(following)) {
        break;
      }
  
      detected = true;
      state.position++;
  
      if (skipSeparationSpace(state, true, -1)) {
        if (state.lineIndent <= nodeIndent) {
          _result.push(null);
          ch = state.input.charCodeAt(state.position);
          continue;
        }
      }
  
      _line = state.line;
      composeNode(state, nodeIndent, CONTEXT_BLOCK_IN, false, true);
      _result.push(state.result);
      skipSeparationSpace(state, true, -1);
  
      ch = state.input.charCodeAt(state.position);
  
      if ((state.line === _line || state.lineIndent > nodeIndent) && (ch !== 0)) {
        throwError(state, 'bad indentation of a sequence entry');
      } else if (state.lineIndent < nodeIndent) {
        break;
      }
    }
  
    if (detected) {
      state.tag = _tag;
      state.anchor = _anchor;
      state.kind = 'sequence';
      state.result = _result;
      return true;
    }
    return false;
  }
  
  function readBlockMapping(state, nodeIndent, flowIndent) {
    var following,
        allowCompact,
        _line,
        _pos,
        _tag          = state.tag,
        _anchor       = state.anchor,
        _result       = {},
        overridableKeys = {},
        keyTag        = null,
        keyNode       = null,
        valueNode     = null,
        atExplicitKey = false,
        detected      = false,
        ch;
  
    if (state.anchor !== null) {
      state.anchorMap[state.anchor] = _result;
    }
  
    ch = state.input.charCodeAt(state.position);
  
    while (ch !== 0) {
      following = state.input.charCodeAt(state.position + 1);
      _line = state.line; // Save the current line.
      _pos = state.position;
  
      //
      // Explicit notation case. There are two separate blocks:
      // first for the key (denoted by "?") and second for the value (denoted by ":")
      //
      if ((ch === 0x3F/* ? */ || ch === 0x3A/* : */) && is_WS_OR_EOL(following)) {
  
        if (ch === 0x3F/* ? */) {
          if (atExplicitKey) {
            storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, null);
            keyTag = keyNode = valueNode = null;
          }
  
          detected = true;
          atExplicitKey = true;
          allowCompact = true;
  
        } else if (atExplicitKey) {
          // i.e. 0x3A/* : */ === character after the explicit key.
          atExplicitKey = false;
          allowCompact = true;
  
        } else {
          throwError(state, 'incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line');
        }
  
        state.position += 1;
        ch = following;
  
      //
      // Implicit notation case. Flow-style node as the key first, then ":", and the value.
      //
      } else if (composeNode(state, flowIndent, CONTEXT_FLOW_OUT, false, true)) {
  
        if (state.line === _line) {
          ch = state.input.charCodeAt(state.position);
  
          while (is_WHITE_SPACE(ch)) {
            ch = state.input.charCodeAt(++state.position);
          }
  
          if (ch === 0x3A/* : */) {
            ch = state.input.charCodeAt(++state.position);
  
            if (!is_WS_OR_EOL(ch)) {
              throwError(state, 'a whitespace character is expected after the key-value separator within a block mapping');
            }
  
            if (atExplicitKey) {
              storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, null);
              keyTag = keyNode = valueNode = null;
            }
  
            detected = true;
            atExplicitKey = false;
            allowCompact = false;
            keyTag = state.tag;
            keyNode = state.result;
  
          } else if (detected) {
            throwError(state, 'can not read an implicit mapping pair; a colon is missed');
  
          } else {
            state.tag = _tag;
            state.anchor = _anchor;
            return true; // Keep the result of `composeNode`.
          }
  
        } else if (detected) {
          throwError(state, 'can not read a block mapping entry; a multiline key may not be an implicit key');
  
        } else {
          state.tag = _tag;
          state.anchor = _anchor;
          return true; // Keep the result of `composeNode`.
        }
  
      } else {
        break; // Reading is done. Go to the epilogue.
      }
  
      //
      // Common reading code for both explicit and implicit notations.
      //
      if (state.line === _line || state.lineIndent > nodeIndent) {
        if (composeNode(state, nodeIndent, CONTEXT_BLOCK_OUT, true, allowCompact)) {
          if (atExplicitKey) {
            keyNode = state.result;
          } else {
            valueNode = state.result;
          }
        }
  
        if (!atExplicitKey) {
          storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode, _line, _pos);
          keyTag = keyNode = valueNode = null;
        }
  
        skipSeparationSpace(state, true, -1);
        ch = state.input.charCodeAt(state.position);
      }
  
      if (state.lineIndent > nodeIndent && (ch !== 0)) {
        throwError(state, 'bad indentation of a mapping entry');
      } else if (state.lineIndent < nodeIndent) {
        break;
      }
    }
  
    //
    // Epilogue.
    //
  
    // Special case: last mapping's node contains only the key in explicit notation.
    if (atExplicitKey) {
      storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, null);
    }
  
    // Expose the resulting mapping.
    if (detected) {
      state.tag = _tag;
      state.anchor = _anchor;
      state.kind = 'mapping';
      state.result = _result;
    }
  
    return detected;
  }
  
  function readTagProperty(state) {
    var _position,
        isVerbatim = false,
        isNamed    = false,
        tagHandle,
        tagName,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch !== 0x21/* ! */) return false;
  
    if (state.tag !== null) {
      throwError(state, 'duplication of a tag property');
    }
  
    ch = state.input.charCodeAt(++state.position);
  
    if (ch === 0x3C/* < */) {
      isVerbatim = true;
      ch = state.input.charCodeAt(++state.position);
  
    } else if (ch === 0x21/* ! */) {
      isNamed = true;
      tagHandle = '!!';
      ch = state.input.charCodeAt(++state.position);
  
    } else {
      tagHandle = '!';
    }
  
    _position = state.position;
  
    if (isVerbatim) {
      do { ch = state.input.charCodeAt(++state.position); }
      while (ch !== 0 && ch !== 0x3E/* > */);
  
      if (state.position < state.length) {
        tagName = state.input.slice(_position, state.position);
        ch = state.input.charCodeAt(++state.position);
      } else {
        throwError(state, 'unexpected end of the stream within a verbatim tag');
      }
    } else {
      while (ch !== 0 && !is_WS_OR_EOL(ch)) {
  
        if (ch === 0x21/* ! */) {
          if (!isNamed) {
            tagHandle = state.input.slice(_position - 1, state.position + 1);
  
            if (!PATTERN_TAG_HANDLE.test(tagHandle)) {
              throwError(state, 'named tag handle cannot contain such characters');
            }
  
            isNamed = true;
            _position = state.position + 1;
          } else {
            throwError(state, 'tag suffix cannot contain exclamation marks');
          }
        }
  
        ch = state.input.charCodeAt(++state.position);
      }
  
      tagName = state.input.slice(_position, state.position);
  
      if (PATTERN_FLOW_INDICATORS.test(tagName)) {
        throwError(state, 'tag suffix cannot contain flow indicator characters');
      }
    }
  
    if (tagName && !PATTERN_TAG_URI.test(tagName)) {
      throwError(state, 'tag name cannot contain such characters: ' + tagName);
    }
  
    if (isVerbatim) {
      state.tag = tagName;
  
    } else if (_hasOwnProperty.call(state.tagMap, tagHandle)) {
      state.tag = state.tagMap[tagHandle] + tagName;
  
    } else if (tagHandle === '!') {
      state.tag = '!' + tagName;
  
    } else if (tagHandle === '!!') {
      state.tag = 'tag:yaml.org,2002:' + tagName;
  
    } else {
      throwError(state, 'undeclared tag handle "' + tagHandle + '"');
    }
  
    return true;
  }
  
  function readAnchorProperty(state) {
    var _position,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch !== 0x26/* & */) return false;
  
    if (state.anchor !== null) {
      throwError(state, 'duplication of an anchor property');
    }
  
    ch = state.input.charCodeAt(++state.position);
    _position = state.position;
  
    while (ch !== 0 && !is_WS_OR_EOL(ch) && !is_FLOW_INDICATOR(ch)) {
      ch = state.input.charCodeAt(++state.position);
    }
  
    if (state.position === _position) {
      throwError(state, 'name of an anchor node must contain at least one character');
    }
  
    state.anchor = state.input.slice(_position, state.position);
    return true;
  }
  
  function readAlias(state) {
    var _position, alias,
        ch;
  
    ch = state.input.charCodeAt(state.position);
  
    if (ch !== 0x2A/* * */) return false;
  
    ch = state.input.charCodeAt(++state.position);
    _position = state.position;
  
    while (ch !== 0 && !is_WS_OR_EOL(ch) && !is_FLOW_INDICATOR(ch)) {
      ch = state.input.charCodeAt(++state.position);
    }
  
    if (state.position === _position) {
      throwError(state, 'name of an alias node must contain at least one character');
    }
  
    alias = state.input.slice(_position, state.position);
  
    if (!state.anchorMap.hasOwnProperty(alias)) {
      throwError(state, 'unidentified alias "' + alias + '"');
    }
  
    state.result = state.anchorMap[alias];
    skipSeparationSpace(state, true, -1);
    return true;
  }
  
  function composeNode(state, parentIndent, nodeContext, allowToSeek, allowCompact) {
    var allowBlockStyles,
        allowBlockScalars,
        allowBlockCollections,
        indentStatus = 1, // 1: this>parent, 0: this=parent, -1: this<parent
        atNewLine  = false,
        hasContent = false,
        typeIndex,
        typeQuantity,
        type,
        flowIndent,
        blockIndent;
  
    if (state.listener !== null) {
      state.listener('open', state);
    }
  
    state.tag    = null;
    state.anchor = null;
    state.kind   = null;
    state.result = null;
  
    allowBlockStyles = allowBlockScalars = allowBlockCollections =
      CONTEXT_BLOCK_OUT === nodeContext ||
      CONTEXT_BLOCK_IN  === nodeContext;
  
    if (allowToSeek) {
      if (skipSeparationSpace(state, true, -1)) {
        atNewLine = true;
  
        if (state.lineIndent > parentIndent) {
          indentStatus = 1;
        } else if (state.lineIndent === parentIndent) {
          indentStatus = 0;
        } else if (state.lineIndent < parentIndent) {
          indentStatus = -1;
        }
      }
    }
  
    if (indentStatus === 1) {
      while (readTagProperty(state) || readAnchorProperty(state)) {
        if (skipSeparationSpace(state, true, -1)) {
          atNewLine = true;
          allowBlockCollections = allowBlockStyles;
  
          if (state.lineIndent > parentIndent) {
            indentStatus = 1;
          } else if (state.lineIndent === parentIndent) {
            indentStatus = 0;
          } else if (state.lineIndent < parentIndent) {
            indentStatus = -1;
          }
        } else {
          allowBlockCollections = false;
        }
      }
    }
  
    if (allowBlockCollections) {
      allowBlockCollections = atNewLine || allowCompact;
    }
  
    if (indentStatus === 1 || CONTEXT_BLOCK_OUT === nodeContext) {
      if (CONTEXT_FLOW_IN === nodeContext || CONTEXT_FLOW_OUT === nodeContext) {
        flowIndent = parentIndent;
      } else {
        flowIndent = parentIndent + 1;
      }
  
      blockIndent = state.position - state.lineStart;
  
      if (indentStatus === 1) {
        if (allowBlockCollections &&
            (readBlockSequence(state, blockIndent) ||
             readBlockMapping(state, blockIndent, flowIndent)) ||
            readFlowCollection(state, flowIndent)) {
          hasContent = true;
        } else {
          if ((allowBlockScalars && readBlockScalar(state, flowIndent)) ||
              readSingleQuotedScalar(state, flowIndent) ||
              readDoubleQuotedScalar(state, flowIndent)) {
            hasContent = true;
  
          } else if (readAlias(state)) {
            hasContent = true;
  
            if (state.tag !== null || state.anchor !== null) {
              throwError(state, 'alias node should not have any properties');
            }
  
          } else if (readPlainScalar(state, flowIndent, CONTEXT_FLOW_IN === nodeContext)) {
            hasContent = true;
  
            if (state.tag === null) {
              state.tag = '?';
            }
          }
  
          if (state.anchor !== null) {
            state.anchorMap[state.anchor] = state.result;
          }
        }
      } else if (indentStatus === 0) {
        // Special case: block sequences are allowed to have same indentation level as the parent.
        // http://www.yaml.org/spec/1.2/spec.html#id2799784
        hasContent = allowBlockCollections && readBlockSequence(state, blockIndent);
      }
    }
  
    if (state.tag !== null && state.tag !== '!') {
      if (state.tag === '?') {
        // Implicit resolving is not allowed for non-scalar types, and '?'
        // non-specific tag is only automatically assigned to plain scalars.
        //
        // We only need to check kind conformity in case user explicitly assigns '?'
        // tag, for example like this: "!<?> [0]"
        //
        if (state.result !== null && state.kind !== 'scalar') {
          throwError(state, 'unacceptable node kind for !<?> tag; it should be "scalar", not "' + state.kind + '"');
        }
  
        for (typeIndex = 0, typeQuantity = state.implicitTypes.length; typeIndex < typeQuantity; typeIndex += 1) {
          type = state.implicitTypes[typeIndex];
  
          if (type.resolve(state.result)) { // `state.result` updated in resolver if matched
            state.result = type.construct(state.result);
            state.tag = type.tag;
            if (state.anchor !== null) {
              state.anchorMap[state.anchor] = state.result;
            }
            break;
          }
        }
      } else if (_hasOwnProperty.call(state.typeMap[state.kind || 'fallback'], state.tag)) {
        type = state.typeMap[state.kind || 'fallback'][state.tag];
  
        if (state.result !== null && type.kind !== state.kind) {
          throwError(state, 'unacceptable node kind for !<' + state.tag + '> tag; it should be "' + type.kind + '", not "' + state.kind + '"');
        }
  
        if (!type.resolve(state.result)) { // `state.result` updated in resolver if matched
          throwError(state, 'cannot resolve a node with !<' + state.tag + '> explicit tag');
        } else {
          state.result = type.construct(state.result);
          if (state.anchor !== null) {
            state.anchorMap[state.anchor] = state.result;
          }
        }
      } else {
        throwError(state, 'unknown tag !<' + state.tag + '>');
      }
    }
  
    if (state.listener !== null) {
      state.listener('close', state);
    }
    return state.tag !== null ||  state.anchor !== null || hasContent;
  }
  
  function readDocument(state) {
    var documentStart = state.position,
        _position,
        directiveName,
        directiveArgs,
        hasDirectives = false,
        ch;
  
    state.version = null;
    state.checkLineBreaks = state.legacy;
    state.tagMap = {};
    state.anchorMap = {};
  
    while ((ch = state.input.charCodeAt(state.position)) !== 0) {
      skipSeparationSpace(state, true, -1);
  
      ch = state.input.charCodeAt(state.position);
  
      if (state.lineIndent > 0 || ch !== 0x25/* % */) {
        break;
      }
  
      hasDirectives = true;
      ch = state.input.charCodeAt(++state.position);
      _position = state.position;
  
      while (ch !== 0 && !is_WS_OR_EOL(ch)) {
        ch = state.input.charCodeAt(++state.position);
      }
  
      directiveName = state.input.slice(_position, state.position);
      directiveArgs = [];
  
      if (directiveName.length < 1) {
        throwError(state, 'directive name must not be less than one character in length');
      }
  
      while (ch !== 0) {
        while (is_WHITE_SPACE(ch)) {
          ch = state.input.charCodeAt(++state.position);
        }
  
        if (ch === 0x23/* # */) {
          do { ch = state.input.charCodeAt(++state.position); }
          while (ch !== 0 && !is_EOL(ch));
          break;
        }
  
        if (is_EOL(ch)) break;
  
        _position = state.position;
  
        while (ch !== 0 && !is_WS_OR_EOL(ch)) {
          ch = state.input.charCodeAt(++state.position);
        }
  
        directiveArgs.push(state.input.slice(_position, state.position));
      }
  
      if (ch !== 0) readLineBreak(state);
  
      if (_hasOwnProperty.call(directiveHandlers, directiveName)) {
        directiveHandlers[directiveName](state, directiveName, directiveArgs);
      } else {
        throwWarning(state, 'unknown document directive "' + directiveName + '"');
      }
    }
  
    skipSeparationSpace(state, true, -1);
  
    if (state.lineIndent === 0 &&
        state.input.charCodeAt(state.position)     === 0x2D/* - */ &&
        state.input.charCodeAt(state.position + 1) === 0x2D/* - */ &&
        state.input.charCodeAt(state.position + 2) === 0x2D/* - */) {
      state.position += 3;
      skipSeparationSpace(state, true, -1);
  
    } else if (hasDirectives) {
      throwError(state, 'directives end mark is expected');
    }
  
    composeNode(state, state.lineIndent - 1, CONTEXT_BLOCK_OUT, false, true);
    skipSeparationSpace(state, true, -1);
  
    if (state.checkLineBreaks &&
        PATTERN_NON_ASCII_LINE_BREAKS.test(state.input.slice(documentStart, state.position))) {
      throwWarning(state, 'non-ASCII line breaks are interpreted as content');
    }
  
    state.documents.push(state.result);
  
    if (state.position === state.lineStart && testDocumentSeparator(state)) {
  
      if (state.input.charCodeAt(state.position) === 0x2E/* . */) {
        state.position += 3;
        skipSeparationSpace(state, true, -1);
      }
      return;
    }
  
    if (state.position < (state.length - 1)) {
      throwError(state, 'end of the stream or a document separator is expected');
    } else {
      return;
    }
  }
  
  
  function loadDocuments(input, options) {
    input = String(input);
    options = options || {};
  
    if (input.length !== 0) {
  
      // Add tailing `\n` if not exists
      if (input.charCodeAt(input.length - 1) !== 0x0A/* LF */ &&
          input.charCodeAt(input.length - 1) !== 0x0D/* CR */) {
        input += '\n';
      }
  
      // Strip BOM
      if (input.charCodeAt(0) === 0xFEFF) {
        input = input.slice(1);
      }
    }
  
    var state = new State(input, options);
  
    var nullpos = input.indexOf('\0');
  
    if (nullpos !== -1) {
      state.position = nullpos;
      throwError(state, 'null byte is not allowed in input');
    }
  
    // Use 0 as string terminator. That significantly simplifies bounds check.
    state.input += '\0';
  
    while (state.input.charCodeAt(state.position) === 0x20/* Space */) {
      state.lineIndent += 1;
      state.position += 1;
    }
  
    while (state.position < (state.length - 1)) {
      readDocument(state);
    }
  
    return state.documents;
  }
  
  
  function loadAll(input, iterator, options) {
    var documents = loadDocuments(input, options), index, length;
  
    if (typeof iterator !== 'function') {
      return documents;
    }
  
    for (index = 0, length = documents.length; index < length; index += 1) {
      iterator(documents[index]);
    }
  }
  
  
  function load(input, options) {
    var documents = loadDocuments(input, options);
  
    if (documents.length === 0) {
      /*eslint-disable no-undefined*/
      return undefined;
    } else if (documents.length === 1) {
      return documents[0];
    }
    throw new YAMLException('expected a single document in the stream, but found more');
  }
  
  
  function safeLoadAll(input, output, options) {
    if (typeof output === 'function') {
      loadAll(input, output, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));
    } else {
      return loadAll(input, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));
    }
  }
  
  
  function safeLoad(input, options) {
    return load(input, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));
  }
  
  
  module.exports.loadAll     = loadAll;
  module.exports.load        = load;
  module.exports.safeLoadAll = safeLoadAll;
  module.exports.safeLoad    = safeLoad;
  