source: imaps-frontend/node_modules/js-yaml/dist/js-yaml.mjs

/*! js-yaml 4.1.0 https://github.com/nodeca/js-yaml @license MIT */
function isNothing(subject) {
  return (typeof subject === 'undefined') || (subject === null);
}


function isObject(subject) {
  return (typeof subject === 'object') && (subject !== null);
}


function toArray(sequence) {
  if (Array.isArray(sequence)) return sequence;
  else if (isNothing(sequence)) return [];

  return [ sequence ];
}


function extend(target, source) {
  var index, length, key, sourceKeys;

  if (source) {
    sourceKeys = Object.keys(source);

    for (index = 0, length = sourceKeys.length; index < length; index += 1) {
      key = sourceKeys[index];
      target[key] = source[key];
    }
  }

  return target;
}


function repeat(string, count) {
  var result = '', cycle;

  for (cycle = 0; cycle < count; cycle += 1) {
    result += string;
  }

  return result;
}


function isNegativeZero(number) {
  return (number === 0) && (Number.NEGATIVE_INFINITY === 1 / number);
}


var isNothing_1      = isNothing;
var isObject_1       = isObject;
var toArray_1        = toArray;
var repeat_1         = repeat;
var isNegativeZero_1 = isNegativeZero;
var extend_1         = extend;

var common = {
        isNothing: isNothing_1,
        isObject: isObject_1,
        toArray: toArray_1,
        repeat: repeat_1,
        isNegativeZero: isNegativeZero_1,
        extend: extend_1
};

// YAML error class. http://stackoverflow.com/questions/8458984


function formatError(exception, compact) {
  var where = '', message = exception.reason || '(unknown reason)';

  if (!exception.mark) return message;

  if (exception.mark.name) {
    where += 'in "' + exception.mark.name + '" ';
  }

  where += '(' + (exception.mark.line + 1) + ':' + (exception.mark.column + 1) + ')';

  if (!compact && exception.mark.snippet) {
    where += '\n\n' + exception.mark.snippet;
  }

  return message + ' ' + where;
}


function YAMLException$1(reason, mark) {
  // Super constructor
  Error.call(this);

  this.name = 'YAMLException';
  this.reason = reason;
  this.mark = mark;
  this.message = formatError(this, false);

  // Include stack trace in error object
  if (Error.captureStackTrace) {
    // Chrome and NodeJS
    Error.captureStackTrace(this, this.constructor);
  } else {
    // FF, IE 10+ and Safari 6+. Fallback for others
    this.stack = (new Error()).stack || '';
  }
}


// Inherit from Error
YAMLException$1.prototype = Object.create(Error.prototype);
YAMLException$1.prototype.constructor = YAMLException$1;


YAMLException$1.prototype.toString = function toString(compact) {
  return this.name + ': ' + formatError(this, compact);
};


var exception = YAMLException$1;

// get snippet for a single line, respecting maxLength
function getLine(buffer, lineStart, lineEnd, position, maxLineLength) {
  var head = '';
  var tail = '';
  var maxHalfLength = Math.floor(maxLineLength / 2) - 1;

  if (position - lineStart > maxHalfLength) {
    head = ' ... ';
    lineStart = position - maxHalfLength + head.length;
  }

  if (lineEnd - position > maxHalfLength) {
    tail = ' ...';
    lineEnd = position + maxHalfLength - tail.length;
  }

  return {
    str: head + buffer.slice(lineStart, lineEnd).replace(/\t/g, '→') + tail,
    pos: position - lineStart + head.length // relative position
  };
}


function padStart(string, max) {
  return common.repeat(' ', max - string.length) + string;
}


function makeSnippet(mark, options) {
  options = Object.create(options || null);

  if (!mark.buffer) return null;

  if (!options.maxLength) options.maxLength = 79;
  if (typeof options.indent      !== 'number') options.indent      = 1;
  if (typeof options.linesBefore !== 'number') options.linesBefore = 3;
  if (typeof options.linesAfter  !== 'number') options.linesAfter  = 2;

  var re = /\r?\n|\r|\0/g;
  var lineStarts = [ 0 ];
  var lineEnds = [];
  var match;
  var foundLineNo = -1;

  while ((match = re.exec(mark.buffer))) {
    lineEnds.push(match.index);
    lineStarts.push(match.index + match[0].length);

    if (mark.position <= match.index && foundLineNo < 0) {
      foundLineNo = lineStarts.length - 2;
    }
  }

  if (foundLineNo < 0) foundLineNo = lineStarts.length - 1;

  var result = '', i, line;
  var lineNoLength = Math.min(mark.line + options.linesAfter, lineEnds.length).toString().length;
  var maxLineLength = options.maxLength - (options.indent + lineNoLength + 3);

  for (i = 1; i <= options.linesBefore; i++) {
    if (foundLineNo - i < 0) break;
    line = getLine(
      mark.buffer,
      lineStarts[foundLineNo - i],
      lineEnds[foundLineNo - i],
      mark.position - (lineStarts[foundLineNo] - lineStarts[foundLineNo - i]),
      maxLineLength
    );
    result = common.repeat(' ', options.indent) + padStart((mark.line - i + 1).toString(), lineNoLength) +
      ' | ' + line.str + '\n' + result;
  }

  line = getLine(mark.buffer, lineStarts[foundLineNo], lineEnds[foundLineNo], mark.position, maxLineLength);
  result += common.repeat(' ', options.indent) + padStart((mark.line + 1).toString(), lineNoLength) +
    ' | ' + line.str + '\n';
  result += common.repeat('-', options.indent + lineNoLength + 3 + line.pos) + '^' + '\n';

  for (i = 1; i <= options.linesAfter; i++) {
    if (foundLineNo + i >= lineEnds.length) break;
    line = getLine(
      mark.buffer,
      lineStarts[foundLineNo + i],
      lineEnds[foundLineNo + i],
      mark.position - (lineStarts[foundLineNo] - lineStarts[foundLineNo + i]),
      maxLineLength
    );
    result += common.repeat(' ', options.indent) + padStart((mark.line + i + 1).toString(), lineNoLength) +
      ' | ' + line.str + '\n';
  }

  return result.replace(/\n$/, '');
}


var snippet = makeSnippet;

var TYPE_CONSTRUCTOR_OPTIONS = [
  'kind',
  'multi',
  'resolve',
  'construct',
  'instanceOf',
  'predicate',
  'represent',
  'representName',
  'defaultStyle',
  'styleAliases'
];

var YAML_NODE_KINDS = [
  'scalar',
  'sequence',
  'mapping'
];

function compileStyleAliases(map) {
  var result = {};

  if (map !== null) {
    Object.keys(map).forEach(function (style) {
      map[style].forEach(function (alias) {
        result[String(alias)] = style;
      });
    });
  }

  return result;
}

function Type$1(tag, options) {
  options = options || {};

  Object.keys(options).forEach(function (name) {
    if (TYPE_CONSTRUCTOR_OPTIONS.indexOf(name) === -1) {
      throw new exception('Unknown option "' + name + '" is met in definition of "' + tag + '" YAML type.');
    }
  });

  // TODO: Add tag format check.
  this.options       = options; // keep original options in case user wants to extend this type later
  this.tag           = tag;
  this.kind          = options['kind']          || null;
  this.resolve       = options['resolve']       || function () { return true; };
  this.construct     = options['construct']     || function (data) { return data; };
  this.instanceOf    = options['instanceOf']    || null;
  this.predicate     = options['predicate']     || null;
  this.represent     = options['represent']     || null;
  this.representName = options['representName'] || null;
  this.defaultStyle  = options['defaultStyle']  || null;
  this.multi         = options['multi']         || false;
  this.styleAliases  = compileStyleAliases(options['styleAliases'] || null);

  if (YAML_NODE_KINDS.indexOf(this.kind) === -1) {
    throw new exception('Unknown kind "' + this.kind + '" is specified for "' + tag + '" YAML type.');
  }
}

var type = Type$1;

/*eslint-disable max-len*/





function compileList(schema, name) {
  var result = [];

  schema[name].forEach(function (currentType) {
    var newIndex = result.length;

    result.forEach(function (previousType, previousIndex) {
      if (previousType.tag === currentType.tag &&
          previousType.kind === currentType.kind &&
          previousType.multi === currentType.multi) {

        newIndex = previousIndex;
      }
    });

    result[newIndex] = currentType;
  });

  return result;
}


function compileMap(/* lists... */) {
  var result = {
        scalar: {},
        sequence: {},
        mapping: {},
        fallback: {},
        multi: {
          scalar: [],
          sequence: [],
          mapping: [],
          fallback: []
        }
      }, index, length;

  function collectType(type) {
    if (type.multi) {
      result.multi[type.kind].push(type);
      result.multi['fallback'].push(type);
    } else {
      result[type.kind][type.tag] = result['fallback'][type.tag] = type;
    }
  }

  for (index = 0, length = arguments.length; index < length; index += 1) {
    arguments[index].forEach(collectType);
  }
  return result;
}


function Schema$1(definition) {
  return this.extend(definition);
}


Schema$1.prototype.extend = function extend(definition) {
  var implicit = [];
  var explicit = [];

  if (definition instanceof type) {
    // Schema.extend(type)
    explicit.push(definition);

  } else if (Array.isArray(definition)) {
    // Schema.extend([ type1, type2, ... ])
    explicit = explicit.concat(definition);

  } else if (definition && (Array.isArray(definition.implicit) || Array.isArray(definition.explicit))) {
    // Schema.extend({ explicit: [ type1, type2, ... ], implicit: [ type1, type2, ... ] })
    if (definition.implicit) implicit = implicit.concat(definition.implicit);
    if (definition.explicit) explicit = explicit.concat(definition.explicit);

  } else {
    throw new exception('Schema.extend argument should be a Type, [ Type ], ' +
      'or a schema definition ({ implicit: [...], explicit: [...] })');
  }

  implicit.forEach(function (type$1) {
    if (!(type$1 instanceof type)) {
      throw new exception('Specified list of YAML types (or a single Type object) contains a non-Type object.');
    }

    if (type$1.loadKind && type$1.loadKind !== 'scalar') {
      throw new exception('There is a non-scalar type in the implicit list of a schema. Implicit resolving of such types is not supported.');
    }

    if (type$1.multi) {
      throw new exception('There is a multi type in the implicit list of a schema. Multi tags can only be listed as explicit.');
    }
  });

  explicit.forEach(function (type$1) {
    if (!(type$1 instanceof type)) {
      throw new exception('Specified list of YAML types (or a single Type object) contains a non-Type object.');
    }
  });

  var result = Object.create(Schema$1.prototype);

  result.implicit = (this.implicit || []).concat(implicit);
  result.explicit = (this.explicit || []).concat(explicit);

  result.compiledImplicit = compileList(result, 'implicit');
  result.compiledExplicit = compileList(result, 'explicit');
  result.compiledTypeMap  = compileMap(result.compiledImplicit, result.compiledExplicit);

  return result;
};


var schema = Schema$1;

var str = new type('tag:yaml.org,2002:str', {
  kind: 'scalar',
  construct: function (data) { return data !== null ? data : ''; }
});

var seq = new type('tag:yaml.org,2002:seq', {
  kind: 'sequence',
  construct: function (data) { return data !== null ? data : []; }
});

var map = new type('tag:yaml.org,2002:map', {
  kind: 'mapping',
  construct: function (data) { return data !== null ? data : {}; }
});

var failsafe = new schema({
  explicit: [
    str,
    seq,
    map
  ]
});

function resolveYamlNull(data) {
  if (data === null) return true;

  var max = data.length;

  return (max === 1 && data === '~') ||
         (max === 4 && (data === 'null' || data === 'Null' || data === 'NULL'));
}

function constructYamlNull() {
  return null;
}

function isNull(object) {
  return object === null;
}

var _null = new type('tag:yaml.org,2002:null', {
  kind: 'scalar',
  resolve: resolveYamlNull,
  construct: constructYamlNull,
  predicate: isNull,
  represent: {
    canonical: function () { return '~';    },
    lowercase: function () { return 'null'; },
    uppercase: function () { return 'NULL'; },
    camelcase: function () { return 'Null'; },
    empty:     function () { return '';     }
  },
  defaultStyle: 'lowercase'
});

function resolveYamlBoolean(data) {
  if (data === null) return false;

  var max = data.length;

  return (max === 4 && (data === 'true' || data === 'True' || data === 'TRUE')) ||
         (max === 5 && (data === 'false' || data === 'False' || data === 'FALSE'));
}

function constructYamlBoolean(data) {
  return data === 'true' ||
         data === 'True' ||
         data === 'TRUE';
}

function isBoolean(object) {
  return Object.prototype.toString.call(object) === '[object Boolean]';
}

var bool = new type('tag:yaml.org,2002:bool', {
  kind: 'scalar',
  resolve: resolveYamlBoolean,
  construct: constructYamlBoolean,
  predicate: isBoolean,
  represent: {
    lowercase: function (object) { return object ? 'true' : 'false'; },
    uppercase: function (object) { return object ? 'TRUE' : 'FALSE'; },
    camelcase: function (object) { return object ? 'True' : 'False'; }
  },
  defaultStyle: 'lowercase'
});

function isHexCode(c) {
  return ((0x30/* 0 */ <= c) && (c <= 0x39/* 9 */)) ||
         ((0x41/* A */ <= c) && (c <= 0x46/* F */)) ||
         ((0x61/* a */ <= c) && (c <= 0x66/* f */));
}

function isOctCode(c) {
  return ((0x30/* 0 */ <= c) && (c <= 0x37/* 7 */));
}

function isDecCode(c) {
  return ((0x30/* 0 */ <= c) && (c <= 0x39/* 9 */));
}

function resolveYamlInteger(data) {
  if (data === null) return false;

  var max = data.length,
      index = 0,
      hasDigits = false,
      ch;

  if (!max) return false;

  ch = data[index];

  // sign
  if (ch === '-' || ch === '+') {
    ch = data[++index];
  }

  if (ch === '0') {
    // 0
    if (index + 1 === max) return true;
    ch = data[++index];

    // base 2, base 8, base 16

    if (ch === 'b') {
      // base 2
      index++;

      for (; index < max; index++) {
        ch = data[index];
        if (ch === '_') continue;
        if (ch !== '0' && ch !== '1') return false;
        hasDigits = true;
      }
      return hasDigits && ch !== '_';
    }


    if (ch === 'x') {
      // base 16
      index++;

      for (; index < max; index++) {
        ch = data[index];
        if (ch === '_') continue;
        if (!isHexCode(data.charCodeAt(index))) return false;
        hasDigits = true;
      }
      return hasDigits && ch !== '_';
    }


    if (ch === 'o') {
      // base 8
      index++;

      for (; index < max; index++) {
        ch = data[index];
        if (ch === '_') continue;
        if (!isOctCode(data.charCodeAt(index))) return false;
        hasDigits = true;
      }
      return hasDigits && ch !== '_';
    }
  }

  // base 10 (except 0)

  // value should not start with `_`;
  if (ch === '_') return false;

  for (; index < max; index++) {
    ch = data[index];
    if (ch === '_') continue;
    if (!isDecCode(data.charCodeAt(index))) {
      return false;
    }
    hasDigits = true;
  }

  // Should have digits and should not end with `_`
  if (!hasDigits || ch === '_') return false;

  return true;
}

function constructYamlInteger(data) {
  var value = data, sign = 1, ch;

  if (value.indexOf('_') !== -1) {
    value = value.replace(/_/g, '');
  }

  ch = value[0];

  if (ch === '-' || ch === '+') {
    if (ch === '-') sign = -1;
    value = value.slice(1);
    ch = value[0];
  }

  if (value === '0') return 0;

  if (ch === '0') {
    if (value[1] === 'b') return sign * parseInt(value.slice(2), 2);
    if (value[1] === 'x') return sign * parseInt(value.slice(2), 16);
    if (value[1] === 'o') return sign * parseInt(value.slice(2), 8);
  }

  return sign * parseInt(value, 10);
}

function isInteger(object) {
  return (Object.prototype.toString.call(object)) === '[object Number]' &&
         (object % 1 === 0 && !common.isNegativeZero(object));
}

var int = new type('tag:yaml.org,2002:int', {
  kind: 'scalar',
  resolve: resolveYamlInteger,
  construct: constructYamlInteger,
  predicate: isInteger,
  represent: {
    binary:      function (obj) { return obj >= 0 ? '0b' + obj.toString(2) : '-0b' + obj.toString(2).slice(1); },
    octal:       function (obj) { return obj >= 0 ? '0o'  + obj.toString(8) : '-0o'  + obj.toString(8).slice(1); },
    decimal:     function (obj) { return obj.toString(10); },
    /* eslint-disable max-len */
    hexadecimal: function (obj) { return obj >= 0 ? '0x' + obj.toString(16).toUpperCase() :  '-0x' + obj.toString(16).toUpperCase().slice(1); }
  },
  defaultStyle: 'decimal',
  styleAliases: {
    binary:      [ 2,  'bin' ],
    octal:       [ 8,  'oct' ],
    decimal:     [ 10, 'dec' ],
    hexadecimal: [ 16, 'hex' ]
  }
});

var YAML_FLOAT_PATTERN = new RegExp(
  // 2.5e4, 2.5 and integers
  '^(?:[-+]?(?:[0-9][0-9_]*)(?:\\.[0-9_]*)?(?:[eE][-+]?[0-9]+)?' +
  // .2e4, .2
  // special case, seems not from spec
  '|\\.[0-9_]+(?:[eE][-+]?[0-9]+)?' +
  // .inf
  '|[-+]?\\.(?:inf|Inf|INF)' +
  // .nan
  '|\\.(?:nan|NaN|NAN))$');

function resolveYamlFloat(data) {
  if (data === null) return false;

  if (!YAML_FLOAT_PATTERN.test(data) ||
      // Quick hack to not allow integers end with `_`
      // Probably should update regexp & check speed
      data[data.length - 1] === '_') {
    return false;
  }

  return true;
}

function constructYamlFloat(data) {
  var value, sign;

  value  = data.replace(/_/g, '').toLowerCase();
  sign   = value[0] === '-' ? -1 : 1;

  if ('+-'.indexOf(value[0]) >= 0) {
    value = value.slice(1);
  }

  if (value === '.inf') {
    return (sign === 1) ? Number.POSITIVE_INFINITY : Number.NEGATIVE_INFINITY;

  } else if (value === '.nan') {
    return NaN;
  }
  return sign * parseFloat(value, 10);
}


var SCIENTIFIC_WITHOUT_DOT = /^[-+]?[0-9]+e/;

function representYamlFloat(object, style) {
  var res;

  if (isNaN(object)) {
    switch (style) {
      case 'lowercase': return '.nan';
      case 'uppercase': return '.NAN';
      case 'camelcase': return '.NaN';
    }
  } else if (Number.POSITIVE_INFINITY === object) {
    switch (style) {
      case 'lowercase': return '.inf';
      case 'uppercase': return '.INF';
      case 'camelcase': return '.Inf';
    }
  } else if (Number.NEGATIVE_INFINITY === object) {
    switch (style) {
      case 'lowercase': return '-.inf';
      case 'uppercase': return '-.INF';
      case 'camelcase': return '-.Inf';
    }
  } else if (common.isNegativeZero(object)) {
    return '-0.0';
  }

  res = object.toString(10);

  // JS stringifier can build scientific format without dots: 5e-100,
  // while YAML requres dot: 5.e-100. Fix it with simple hack

  return SCIENTIFIC_WITHOUT_DOT.test(res) ? res.replace('e', '.e') : res;
}

function isFloat(object) {
  return (Object.prototype.toString.call(object) === '[object Number]') &&
         (object % 1 !== 0 || common.isNegativeZero(object));
}

var float = new type('tag:yaml.org,2002:float', {
  kind: 'scalar',
  resolve: resolveYamlFloat,
  construct: constructYamlFloat,
  predicate: isFloat,
  represent: representYamlFloat,
  defaultStyle: 'lowercase'
});

var json = failsafe.extend({
  implicit: [
    _null,
    bool,
    int,
    float
  ]
});

var core = json;

var YAML_DATE_REGEXP = new RegExp(
  '^([0-9][0-9][0-9][0-9])'          + // [1] year
  '-([0-9][0-9])'                    + // [2] month
  '-([0-9][0-9])$');                   // [3] day

var YAML_TIMESTAMP_REGEXP = new RegExp(
  '^([0-9][0-9][0-9][0-9])'          + // [1] year
  '-([0-9][0-9]?)'                   + // [2] month
  '-([0-9][0-9]?)'                   + // [3] day
  '(?:[Tt]|[ \\t]+)'                 + // ...
  '([0-9][0-9]?)'                    + // [4] hour
  ':([0-9][0-9])'                    + // [5] minute
  ':([0-9][0-9])'                    + // [6] second
  '(?:\\.([0-9]*))?'                 + // [7] fraction
  '(?:[ \\t]*(Z|([-+])([0-9][0-9]?)' + // [8] tz [9] tz_sign [10] tz_hour
  '(?::([0-9][0-9]))?))?$');           // [11] tz_minute

function resolveYamlTimestamp(data) {
  if (data === null) return false;
  if (YAML_DATE_REGEXP.exec(data) !== null) return true;
  if (YAML_TIMESTAMP_REGEXP.exec(data) !== null) return true;
  return false;
}

function constructYamlTimestamp(data) {
  var match, year, month, day, hour, minute, second, fraction = 0,
      delta = null, tz_hour, tz_minute, date;

  match = YAML_DATE_REGEXP.exec(data);
  if (match === null) match = YAML_TIMESTAMP_REGEXP.exec(data);

  if (match === null) throw new Error('Date resolve error');

  // match: [1] year [2] month [3] day

  year = +(match[1]);
  month = +(match[2]) - 1; // JS month starts with 0
  day = +(match[3]);

  if (!match[4]) { // no hour
    return new Date(Date.UTC(year, month, day));
  }

  // match: [4] hour [5] minute [6] second [7] fraction

  hour = +(match[4]);
  minute = +(match[5]);
  second = +(match[6]);

  if (match[7]) {
    fraction = match[7].slice(0, 3);
    while (fraction.length < 3) { // milli-seconds
      fraction += '0';
    }
    fraction = +fraction;
  }

  // match: [8] tz [9] tz_sign [10] tz_hour [11] tz_minute

  if (match[9]) {
    tz_hour = +(match[10]);
    tz_minute = +(match[11] || 0);
    delta = (tz_hour * 60 + tz_minute) * 60000; // delta in mili-seconds
    if (match[9] === '-') delta = -delta;
  }

  date = new Date(Date.UTC(year, month, day, hour, minute, second, fraction));

  if (delta) date.setTime(date.getTime() - delta);

  return date;
}

function representYamlTimestamp(object /*, style*/) {
  return object.toISOString();
}

var timestamp = new type('tag:yaml.org,2002:timestamp', {
  kind: 'scalar',
  resolve: resolveYamlTimestamp,
  construct: constructYamlTimestamp,
  instanceOf: Date,
  represent: representYamlTimestamp
});

function resolveYamlMerge(data) {
  return data === '<<' || data === null;
}

var merge = new type('tag:yaml.org,2002:merge', {
  kind: 'scalar',
  resolve: resolveYamlMerge
});

/*eslint-disable no-bitwise*/





// [ 64, 65, 66 ] -> [ padding, CR, LF ]
var BASE64_MAP = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n\r';


function resolveYamlBinary(data) {
  if (data === null) return false;

  var code, idx, bitlen = 0, max = data.length, map = BASE64_MAP;

  // Convert one by one.
  for (idx = 0; idx < max; idx++) {
    code = map.indexOf(data.charAt(idx));

    // Skip CR/LF
    if (code > 64) continue;

    // Fail on illegal characters
    if (code < 0) return false;

    bitlen += 6;
  }

  // If there are any bits left, source was corrupted
  return (bitlen % 8) === 0;
}

function constructYamlBinary(data) {
  var idx, tailbits,
      input = data.replace(/[\r\n=]/g, ''), // remove CR/LF & padding to simplify scan
      max = input.length,
      map = BASE64_MAP,
      bits = 0,
      result = [];

  // Collect by 6*4 bits (3 bytes)

  for (idx = 0; idx < max; idx++) {
    if ((idx % 4 === 0) && idx) {
      result.push((bits >> 16) & 0xFF);
      result.push((bits >> 8) & 0xFF);
      result.push(bits & 0xFF);
    }

    bits = (bits << 6) | map.indexOf(input.charAt(idx));
  }

  // Dump tail

  tailbits = (max % 4) * 6;

  if (tailbits === 0) {
    result.push((bits >> 16) & 0xFF);
    result.push((bits >> 8) & 0xFF);
    result.push(bits & 0xFF);
  } else if (tailbits === 18) {
    result.push((bits >> 10) & 0xFF);
    result.push((bits >> 2) & 0xFF);
  } else if (tailbits === 12) {
    result.push((bits >> 4) & 0xFF);
  }

  return new Uint8Array(result);
}

function representYamlBinary(object /*, style*/) {
  var result = '', bits = 0, idx, tail,
      max = object.length,
      map = BASE64_MAP;

  // Convert every three bytes to 4 ASCII characters.

  for (idx = 0; idx < max; idx++) {
    if ((idx % 3 === 0) && idx) {
      result += map[(bits >> 18) & 0x3F];
      result += map[(bits >> 12) & 0x3F];
      result += map[(bits >> 6) & 0x3F];
      result += map[bits & 0x3F];
    }

    bits = (bits << 8) + object[idx];
  }

  // Dump tail

  tail = max % 3;

  if (tail === 0) {
    result += map[(bits >> 18) & 0x3F];
    result += map[(bits >> 12) & 0x3F];
    result += map[(bits >> 6) & 0x3F];
    result += map[bits & 0x3F];
  } else if (tail === 2) {
    result += map[(bits >> 10) & 0x3F];
    result += map[(bits >> 4) & 0x3F];
    result += map[(bits << 2) & 0x3F];
    result += map[64];
  } else if (tail === 1) {
    result += map[(bits >> 2) & 0x3F];
    result += map[(bits << 4) & 0x3F];
    result += map[64];
    result += map[64];
  }

  return result;
}

function isBinary(obj) {
  return Object.prototype.toString.call(obj) ===  '[object Uint8Array]';
}

var binary = new type('tag:yaml.org,2002:binary', {
  kind: 'scalar',
  resolve: resolveYamlBinary,
  construct: constructYamlBinary,
  predicate: isBinary,
  represent: representYamlBinary
});

var _hasOwnProperty$3 = Object.prototype.hasOwnProperty;
var _toString$2       = Object.prototype.toString;

function resolveYamlOmap(data) {
  if (data === null) return true;

  var objectKeys = [], index, length, pair, pairKey, pairHasKey,
      object = data;

  for (index = 0, length = object.length; index < length; index += 1) {
    pair = object[index];
    pairHasKey = false;

    if (_toString$2.call(pair) !== '[object Object]') return false;

    for (pairKey in pair) {
      if (_hasOwnProperty$3.call(pair, pairKey)) {
        if (!pairHasKey) pairHasKey = true;
        else return false;
      }
    }

    if (!pairHasKey) return false;

    if (objectKeys.indexOf(pairKey) === -1) objectKeys.push(pairKey);
    else return false;
  }

  return true;
}

function constructYamlOmap(data) {
  return data !== null ? data : [];
}

var omap = new type('tag:yaml.org,2002:omap', {
  kind: 'sequence',
  resolve: resolveYamlOmap,
  construct: constructYamlOmap
});

var _toString$1 = Object.prototype.toString;

function resolveYamlPairs(data) {
  if (data === null) return true;

  var index, length, pair, keys, result,
      object = data;

  result = new Array(object.length);

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

    if (_toString$1.call(pair) !== '[object Object]') return false;

    keys = Object.keys(pair);

    if (keys.length !== 1) return false;

    result[index] = [ keys[0], pair[keys[0]] ];
  }

  return true;
}

function constructYamlPairs(data) {
  if (data === null) return [];

  var index, length, pair, keys, result,
      object = data;

  result = new Array(object.length);

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

    keys = Object.keys(pair);

    result[index] = [ keys[0], pair[keys[0]] ];
  }

  return result;
}

var pairs = new type('tag:yaml.org,2002:pairs', {
  kind: 'sequence',
  resolve: resolveYamlPairs,
  construct: constructYamlPairs
});

var _hasOwnProperty$2 = Object.prototype.hasOwnProperty;

function resolveYamlSet(data) {
  if (data === null) return true;

  var key, object = data;

  for (key in object) {
    if (_hasOwnProperty$2.call(object, key)) {
      if (object[key] !== null) return false;
    }
  }

  return true;
}

function constructYamlSet(data) {
  return data !== null ? data : {};
}

var set = new type('tag:yaml.org,2002:set', {
  kind: 'mapping',
  resolve: resolveYamlSet,
  construct: constructYamlSet
});

var _default = core.extend({
  implicit: [
    timestamp,
    merge
  ],
  explicit: [
    binary,
    omap,
    pairs,
    set
  ]
});

/*eslint-disable max-len,no-use-before-define*/







var _hasOwnProperty$1 = 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$1(input, options) {
  this.input = input;

  this.filename  = options['filename']  || null;
  this.schema    = options['schema']    || _default;
  this.onWarning = options['onWarning'] || null;
  // (Hidden) Remove? makes the loader to expect YAML 1.1 documents
  // if such documents have no explicit %YAML directive
  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;

  // position of first leading tab in the current line,
  // used to make sure there are no tabs in the indentation
  this.firstTabInLine = -1;

  this.documents = [];

  /*
  this.version;
  this.checkLineBreaks;
  this.tagMap;
  this.anchorMap;
  this.tag;
  this.anchor;
  this.kind;
  this.result;*/

}


function generateError(state, message) {
  var mark = {
    name:     state.filename,
    buffer:   state.input.slice(0, -1), // omit trailing \0
    position: state.position,
    line:     state.line,
    column:   state.position - state.lineStart
  };

  mark.snippet = snippet(mark);

  return new exception(message, mark);
}

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$1.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');
    }

    try {
      prefix = decodeURIComponent(prefix);
    } catch (err) {
      throwError(state, 'tag prefix is malformed: ' + prefix);
    }

    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$1.call(destination, key)) {
      destination[key] = source[key];
      overridableKeys[key] = true;
    }
  }
}

function storeMappingPair(state, _result, overridableKeys, keyTag, keyNode, valueNode,
  startLine, startLineStart, 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$1.call(overridableKeys, keyNode) &&
        _hasOwnProperty$1.call(_result, keyNode)) {
      state.line = startLine || state.line;
      state.lineStart = startLineStart || state.lineStart;
      state.position = startPos || state.position;
      throwError(state, 'duplicated mapping key');
    }

    // used for this specific key only because Object.defineProperty is slow
    if (keyNode === '__proto__') {
      Object.defineProperty(_result, keyNode, {
        configurable: true,
        enumerable: true,
        writable: true,
        value: valueNode
      });
    } else {
      _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;
  state.firstTabInLine = -1;
}

function skipSeparationSpace(state, allowComments, checkIndent) {
  var lineBreaks = 0,
      ch = state.input.charCodeAt(state.position);

  while (ch !== 0) {
    while (is_WHITE_SPACE(ch)) {
      if (ch === 0x09/* Tab */ && state.firstTabInLine === -1) {
        state.firstTabInLine = state.position;
      }
      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,
      _lineStart,
      _pos,
      _tag     = state.tag,
      _result,
      _anchor  = state.anchor,
      following,
      terminator,
      isPair,
      isExplicitPair,
      isMapping,
      overridableKeys = Object.create(null),
      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');
    } else if (ch === 0x2C/* , */) {
      // "flow collection entries can never be completely empty", as per YAML 1.2, section 7.4
      throwError(state, "expected the node content, but found ','");
    }

    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; // Save the current line.
    _lineStart = state.lineStart;
    _pos = state.position;
    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, _line, _lineStart, _pos);
    } else if (isPair) {
      _result.push(storeMappingPair(state, null, overridableKeys, keyTag, keyNode, valueNode, _line, _lineStart, _pos));
    } 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;

  // there is a leading tab before this token, so it can't be a block sequence/mapping;
  // it can still be flow sequence/mapping or a scalar
  if (state.firstTabInLine !== -1) return false;

  if (state.anchor !== null) {
    state.anchorMap[state.anchor] = _result;
  }

  ch = state.input.charCodeAt(state.position);

  while (ch !== 0) {
    if (state.firstTabInLine !== -1) {
      state.position = state.firstTabInLine;
      throwError(state, 'tab characters must not be used in indentation');
    }

    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,
      _keyLine,
      _keyLineStart,
      _keyPos,
      _tag          = state.tag,
      _anchor       = state.anchor,
      _result       = {},
      overridableKeys = Object.create(null),
      keyTag        = null,
      keyNode       = null,
      valueNode     = null,
      atExplicitKey = false,
      detected      = false,
      ch;

  // there is a leading tab before this token, so it can't be a block sequence/mapping;
  // it can still be flow sequence/mapping or a scalar
  if (state.firstTabInLine !== -1) return false;

  if (state.anchor !== null) {
    state.anchorMap[state.anchor] = _result;
  }

  ch = state.input.charCodeAt(state.position);

  while (ch !== 0) {
    if (!atExplicitKey && state.firstTabInLine !== -1) {
      state.position = state.firstTabInLine;
      throwError(state, 'tab characters must not be used in indentation');
    }

    following = state.input.charCodeAt(state.position + 1);
    _line = state.line; // Save the current line.

    //
    // 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, _keyLine, _keyLineStart, _keyPos);
          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 {
      _keyLine = state.line;
      _keyLineStart = state.lineStart;
      _keyPos = state.position;

      if (!composeNode(state, flowIndent, CONTEXT_FLOW_OUT, false, true)) {
        // Neither implicit nor explicit notation.
        // Reading is done. Go to the epilogue.
        break;
      }

      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, _keyLine, _keyLineStart, _keyPos);
            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`.
      }
    }

    //
    // Common reading code for both explicit and implicit notations.
    //
    if (state.line === _line || state.lineIndent > nodeIndent) {
      if (atExplicitKey) {
        _keyLine = state.line;
        _keyLineStart = state.lineStart;
        _keyPos = state.position;
      }

      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, _keyLine, _keyLineStart, _keyPos);
        keyTag = keyNode = valueNode = null;
      }

      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 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, _keyLine, _keyLineStart, _keyPos);
  }

  // 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);
  }

  try {
    tagName = decodeURIComponent(tagName);
  } catch (err) {
    throwError(state, 'tag name is malformed: ' + tagName);
  }

  if (isVerbatim) {
    state.tag = tagName;

  } else if (_hasOwnProperty$1.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 (!_hasOwnProperty$1.call(state.anchorMap, 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,
      typeList,
      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) {
    if (state.anchor !== null) {
      state.anchorMap[state.anchor] = state.result;
    }

  } else 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 (state.tag !== '!') {
    if (_hasOwnProperty$1.call(state.typeMap[state.kind || 'fallback'], state.tag)) {
      type = state.typeMap[state.kind || 'fallback'][state.tag];
    } else {
      // looking for multi type
      type = null;
      typeList = state.typeMap.multi[state.kind || 'fallback'];

      for (typeIndex = 0, typeQuantity = typeList.length; typeIndex < typeQuantity; typeIndex += 1) {
        if (state.tag.slice(0, typeList[typeIndex].tag.length) === typeList[typeIndex].tag) {
          type = typeList[typeIndex];
          break;
        }
      }
    }

    if (!type) {
      throwError(state, 'unknown tag !<' + 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.tag)) { // `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, state.tag);
      if (state.anchor !== null) {
        state.anchorMap[state.anchor] = state.result;
      }
    }
  }

  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 = Object.create(null);
  state.anchorMap = Object.create(null);

  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$1.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$1(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$1(input, iterator, options) {
  if (iterator !== null && typeof iterator === 'object' && typeof options === 'undefined') {
    options = iterator;
    iterator = null;
  }

  var documents = loadDocuments(input, options);

  if (typeof iterator !== 'function') {
    return documents;
  }

  for (var index = 0, length = documents.length; index < length; index += 1) {
    iterator(documents[index]);
  }
}


function load$1(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 exception('expected a single document in the stream, but found more');
}


var loadAll_1 = loadAll$1;
var load_1    = load$1;

var loader = {
        loadAll: loadAll_1,
        load: load_1
};

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





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

var CHAR_BOM                  = 0xFEFF;
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'
];

var DEPRECATED_BASE60_SYNTAX = /^[-+]?[0-9_]+(?::[0-9_]+)+(?:\.[0-9_]*)?$/;

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 exception('code point within a string may not be greater than 0xFFFFFFFF');
  }

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


var QUOTING_TYPE_SINGLE = 1,
    QUOTING_TYPE_DOUBLE = 2;

function State(options) {
  this.schema        = options['schema'] || _default;
  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.quotingType   = options['quotingType'] === '"' ? QUOTING_TYPE_DOUBLE : QUOTING_TYPE_SINGLE;
  this.forceQuotes   = options['forceQuotes'] || false;
  this.replacer      = typeof options['replacer'] === 'function' ? options['replacer'] : null;

  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 !== CHAR_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
// Including s-white (for some reason, examples doesn't match specs in this aspect)
// ns-char ::= c-printable - b-line-feed - b-carriage-return - c-byte-order-mark
function isNsCharOrWhitespace(c) {
  return isPrintable(c)
    && c !== CHAR_BOM
    // - b-char
    && c !== CHAR_CARRIAGE_RETURN
    && c !== CHAR_LINE_FEED;
}

// [127]  ns-plain-safe(c) ::= c = flow-out  ⇒ ns-plain-safe-out
//                             c = flow-in   ⇒ ns-plain-safe-in
//                             c = block-key ⇒ ns-plain-safe-out
//                             c = flow-key  ⇒ ns-plain-safe-in
// [128] ns-plain-safe-out ::= ns-char
// [129]  ns-plain-safe-in ::= ns-char - c-flow-indicator
// [130]  ns-plain-char(c) ::=  ( ns-plain-safe(c) - “:” - “#” )
//                            | ( /* An ns-char preceding */ “#” )
//                            | ( “:” /* Followed by an ns-plain-safe(c) */ )
function isPlainSafe(c, prev, inblock) {
  var cIsNsCharOrWhitespace = isNsCharOrWhitespace(c);
  var cIsNsChar = cIsNsCharOrWhitespace && !isWhitespace(c);
  return (
    // ns-plain-safe
    inblock ? // c = flow-in
      cIsNsCharOrWhitespace
      : cIsNsCharOrWhitespace
        // - 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
  )
    // ns-plain-char
    && c !== CHAR_SHARP // false on '#'
    && !(prev === CHAR_COLON && !cIsNsChar) // false on ': '
    || (isNsCharOrWhitespace(prev) && !isWhitespace(prev) && c === CHAR_SHARP) // change to true on '[^ ]#'
    || (prev === CHAR_COLON && cIsNsChar); // change to true on ':[^ ]'
}

// 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.
  // No support of ( ( “?” | “:” | “-” ) /* Followed by an ns-plain-safe(c)) */ ) part
  return isPrintable(c) && c !== CHAR_BOM
    && !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;
}

// Simplified test for values allowed as the last character in plain style.
function isPlainSafeLast(c) {
  // just not whitespace or colon, it will be checked to be plain character later
  return !isWhitespace(c) && c !== CHAR_COLON;
}

// Same as 'string'.codePointAt(pos), but works in older browsers.
function codePointAt(string, pos) {
  var first = string.charCodeAt(pos), second;
  if (first >= 0xD800 && first <= 0xDBFF && pos + 1 < string.length) {
    second = string.charCodeAt(pos + 1);
    if (second >= 0xDC00 && second <= 0xDFFF) {
      // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
      return (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
    }
  }
  return first;
}

// 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, quotingType, forceQuotes, inblock) {

  var i;
  var char = 0;
  var prevChar = null;
  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(codePointAt(string, 0))
          && isPlainSafeLast(codePointAt(string, string.length - 1));

  if (singleLineOnly || forceQuotes) {
    // Case: no block styles.
    // Check for disallowed characters to rule out plain and single.
    for (i = 0; i < string.length; char >= 0x10000 ? i += 2 : i++) {
      char = codePointAt(string, i);
      if (!isPrintable(char)) {
        return STYLE_DOUBLE;
      }
      plain = plain && isPlainSafe(char, prevChar, inblock);
      prevChar = char;
    }
  } else {
    // Case: block styles permitted.
    for (i = 0; i < string.length; char >= 0x10000 ? i += 2 : i++) {
      char = codePointAt(string, 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, prevChar, inblock);
      prevChar = 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.
    if (plain && !forceQuotes && !testAmbiguousType(string)) {
      return STYLE_PLAIN;
    }
    return quotingType === QUOTING_TYPE_DOUBLE ? STYLE_DOUBLE : 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.
  if (!forceQuotes) {
    return hasFoldableLine ? STYLE_FOLDED : STYLE_LITERAL;
  }
  return quotingType === QUOTING_TYPE_DOUBLE ? STYLE_DOUBLE : STYLE_SINGLE;
}

// 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, inblock) {
  state.dump = (function () {
    if (string.length === 0) {
      return state.quotingType === QUOTING_TYPE_DOUBLE ? '""' : "''";
    }
    if (!state.noCompatMode) {
      if (DEPRECATED_BOOLEANS_SYNTAX.indexOf(string) !== -1 || DEPRECATED_BASE60_SYNTAX.test(string)) {
        return state.quotingType === QUOTING_TYPE_DOUBLE ? ('"' + string + '"') : ("'" + 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, state.quotingType, state.forceQuotes && !iskey, inblock)) {

      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) + '"';
      default:
        throw new exception('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 = 0;
  var escapeSeq;

  for (var i = 0; i < string.length; char >= 0x10000 ? i += 2 : i++) {
    char = codePointAt(string, i);
    escapeSeq = ESCAPE_SEQUENCES[char];

    if (!escapeSeq && isPrintable(char)) {
      result += string[i];
      if (char >= 0x10000) result += string[i + 1];
    } else {
      result += escapeSeq || encodeHex(char);
    }
  }

  return result;
}

function writeFlowSequence(state, level, object) {
  var _result = '',
      _tag    = state.tag,
      index,
      length,
      value;

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

    if (state.replacer) {
      value = state.replacer.call(object, String(index), value);
    }

    // Write only valid elements, put null instead of invalid elements.
    if (writeNode(state, level, value, false, false) ||
        (typeof value === 'undefined' &&
         writeNode(state, level, null, false, false))) {

      if (_result !== '') _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,
      value;

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

    if (state.replacer) {
      value = state.replacer.call(object, String(index), value);
    }

    // Write only valid elements, put null instead of invalid elements.
    if (writeNode(state, level + 1, value, true, true, false, true) ||
        (typeof value === 'undefined' &&
         writeNode(state, level + 1, null, true, true, false, true))) {

      if (!compact || _result !== '') {
        _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 (_result !== '') pairBuffer += ', ';

    if (state.condenseFlow) pairBuffer += '"';

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

    if (state.replacer) {
      objectValue = state.replacer.call(object, objectKey, objectValue);
    }

    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 exception('sortKeys must be a boolean or a function');
  }

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

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

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

    if (state.replacer) {
      objectValue = state.replacer.call(object, objectKey, objectValue);
    }

    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))) {

      if (explicit) {
        if (type.multi && type.representName) {
          state.tag = type.representName(object);
        } else {
          state.tag = type.tag;
        }
      } else {
        state.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 exception('!<' + 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, isblockseq) {
  state.tag = null;
  state.dump = object;

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

  var type = _toString.call(state.dump);
  var inblock = block;
  var tagStr;

  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]') {
      if (block && (state.dump.length !== 0)) {
        if (state.noArrayIndent && !isblockseq && level > 0) {
          writeBlockSequence(state, level - 1, state.dump, compact);
        } else {
          writeBlockSequence(state, level, state.dump, compact);
        }
        if (duplicate) {
          state.dump = '&ref_' + duplicateIndex + state.dump;
        }
      } else {
        writeFlowSequence(state, level, state.dump);
        if (duplicate) {
          state.dump = '&ref_' + duplicateIndex + ' ' + state.dump;
        }
      }
    } else if (type === '[object String]') {
      if (state.tag !== '?') {
        writeScalar(state, state.dump, level, iskey, inblock);
      }
    } else if (type === '[object Undefined]') {
      return false;
    } else {
      if (state.skipInvalid) return false;
      throw new exception('unacceptable kind of an object to dump ' + type);
    }

    if (state.tag !== null && state.tag !== '?') {
      // Need to encode all characters except those allowed by the spec:
      //
      // [35] ns-dec-digit    ::=  [#x30-#x39] /* 0-9 */
      // [36] ns-hex-digit    ::=  ns-dec-digit
      //                         | [#x41-#x46] /* A-F */ | [#x61-#x66] /* a-f */
      // [37] ns-ascii-letter ::=  [#x41-#x5A] /* A-Z */ | [#x61-#x7A] /* a-z */
      // [38] ns-word-char    ::=  ns-dec-digit | ns-ascii-letter | “-”
      // [39] ns-uri-char     ::=  “%” ns-hex-digit ns-hex-digit | ns-word-char | “#”
      //                         | “;” | “/” | “?” | “:” | “@” | “&” | “=” | “+” | “$” | “,”
      //                         | “_” | “.” | “!” | “~” | “*” | “'” | “(” | “)” | “[” | “]”
      //
      // Also need to encode '!' because it has special meaning (end of tag prefix).
      //
      tagStr = encodeURI(
        state.tag[0] === '!' ? state.tag.slice(1) : state.tag
      ).replace(/!/g, '%21');

      if (state.tag[0] === '!') {
        tagStr = '!' + tagStr;
      } else if (tagStr.slice(0, 18) === 'tag:yaml.org,2002:') {
        tagStr = '!!' + tagStr.slice(18);
      } else {
        tagStr = '!<' + tagStr + '>';
      }

      state.dump = tagStr + ' ' + 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$1(input, options) {
  options = options || {};

  var state = new State(options);

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

  var value = input;

  if (state.replacer) {
    value = state.replacer.call({ '': value }, '', value);
  }

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

  return '';
}

var dump_1 = dump$1;

var dumper = {
        dump: dump_1
};

function renamed(from, to) {
  return function () {
    throw new Error('Function yaml.' + from + ' is removed in js-yaml 4. ' +
      'Use yaml.' + to + ' instead, which is now safe by default.');
  };
}


var Type                = type;
var Schema              = schema;
var FAILSAFE_SCHEMA     = failsafe;
var JSON_SCHEMA         = json;
var CORE_SCHEMA         = core;
var DEFAULT_SCHEMA      = _default;
var load                = loader.load;
var loadAll             = loader.loadAll;
var dump                = dumper.dump;
var YAMLException       = exception;

// Re-export all types in case user wants to create custom schema
var types = {
  binary:    binary,
  float:     float,
  map:       map,
  null:      _null,
  pairs:     pairs,
  set:       set,
  timestamp: timestamp,
  bool:      bool,
  int:       int,
  merge:     merge,
  omap:      omap,
  seq:       seq,
  str:       str
};

// Removed functions from JS-YAML 3.0.x
var safeLoad            = renamed('safeLoad', 'load');
var safeLoadAll         = renamed('safeLoadAll', 'loadAll');
var safeDump            = renamed('safeDump', 'dump');

var jsYaml = {
        Type: Type,
        Schema: Schema,
        FAILSAFE_SCHEMA: FAILSAFE_SCHEMA,
        JSON_SCHEMA: JSON_SCHEMA,
        CORE_SCHEMA: CORE_SCHEMA,
        DEFAULT_SCHEMA: DEFAULT_SCHEMA,
        load: load,
        loadAll: loadAll,
        dump: dump,
        YAMLException: YAMLException,
        types: types,
        safeLoad: safeLoad,
        safeLoadAll: safeLoadAll,
        safeDump: safeDump
};

export default jsYaml;
export { CORE_SCHEMA, DEFAULT_SCHEMA, FAILSAFE_SCHEMA, JSON_SCHEMA, Schema, Type, YAMLException, dump, load, loadAll, safeDump, safeLoad, safeLoadAll, types };