/*! js-yaml 4.1.0 https://github.com/nodeca/js-yaml @license MIT */
(function(global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined'
    ? factory(exports)
    : typeof define === 'function' && define.amd
    ? define(['exports'], factory)
    : ((global =
        typeof globalThis !== 'undefined' ? globalThis : global || self),
      factory((global.jsyaml = {})));
})(this, exports => {
  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) {
    let index;
    let length;
    let key;
    let 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) {
    let result = '';
    let cycle;

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

    return result;
  }

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

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

  const 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) {
    let where = '';
    const 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)}`;
  };

  const exception = YAMLException$1;

  // get snippet for a single line, respecting maxLength
  function getLine(buffer, lineStart, lineEnd, position, maxLineLength) {
    let head = '';
    let tail = '';
    const 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;

    const re = /\r?\n|\r|\0/g;
    const lineStarts = [0];
    const lineEnds = [];
    let match;
    let 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;

    let result = '';
    let i;
    let line;
    const lineNoLength = Math.min(
      mark.line + options.linesAfter,
      lineEnds.length
    ).toString().length;
    const 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$/, '');
  }

  const snippet = makeSnippet;

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

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

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

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

    return result;
  }

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

    Object.keys(options).forEach(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.`
      );
    }
  }

  const type = Type$1;

  /* eslint-disable max-len */

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

    schema[name].forEach(currentType => {
      let newIndex = result.length;

      result.forEach((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... */) {
    const result = {
      scalar: {},
      sequence: {},
      mapping: {},
      fallback: {},
      multi: {
        scalar: [],
        sequence: [],
        mapping: [],
        fallback: [],
      },
    };
    let index;
    let 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) {
    let implicit = [];
    let 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(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(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.'
        );
      }
    });

    const 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;
  };

  const schema = Schema$1;

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

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

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

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

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

    const 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;
  }

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

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

    const 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]';
  }

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

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

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

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

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

    const max = data.length;
    let index = 0;
    let hasDigits = false;
    let 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) {
    let value = data;
    let sign = 1;
    let 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)
    );
  }

  const int = new type('tag:yaml.org,2002:int', {
    kind: 'scalar',
    resolve: resolveYamlInteger,
    construct: constructYamlInteger,
    predicate: isInteger,
    represent: {
      binary(obj) {
        return obj >= 0
          ? `0b${obj.toString(2)}`
          : `-0b${obj.toString(2).slice(1)}`;
      },
      octal(obj) {
        return obj >= 0
          ? `0o${obj.toString(8)}`
          : `-0o${obj.toString(8).slice(1)}`;
      },
      decimal(obj) {
        return obj.toString(10);
      },
      /* eslint-disable max-len */
      hexadecimal(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'],
    },
  });

  const 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) {
    let value;
    let 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);
  }

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

  function representYamlFloat(object, style) {
    let 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))
    );
  }

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

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

  const core = json;

  const 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

  const 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) {
    let match;
    let year;
    let month;
    let day;
    let hour;
    let minute;
    let second;
    let fraction = 0;
    let delta = null;
    let tz_hour;
    let tz_minute;
    let 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();
  }

  const 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;
  }

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

  /* eslint-disable no-bitwise */

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

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

    let code;
    let idx;
    let bitlen = 0;
    const max = data.length;
    const 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) {
    let idx;
    let tailbits;
    const input = data.replace(/[\r\n=]/g, ''); // remove CR/LF & padding to simplify scan
    const max = input.length;
    const map = BASE64_MAP;
    let bits = 0;
    const 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 */) {
    let result = '';
    let bits = 0;
    let idx;
    let tail;
    const max = object.length;
    const 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]';
  }

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

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

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

    const objectKeys = [];
    let index;
    let length;
    let pair;
    let pairKey;
    let pairHasKey;
    const 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 : [];
  }

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

  const _toString$1 = Object.prototype.toString;

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

    let index;
    let length;
    let pair;
    let keys;
    let result;
    const 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 [];

    let index;
    let length;
    let pair;
    let keys;
    let result;
    const 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;
  }

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

  const _hasOwnProperty$2 = Object.prototype.hasOwnProperty;

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

    let key;
    const 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 : {};
  }

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

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

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

  const _hasOwnProperty$1 = Object.prototype.hasOwnProperty;

  const CONTEXT_FLOW_IN = 1;
  const CONTEXT_FLOW_OUT = 2;
  const CONTEXT_BLOCK_IN = 3;
  const CONTEXT_BLOCK_OUT = 4;

  const CHOMPING_CLIP = 1;
  const CHOMPING_STRIP = 2;
  const CHOMPING_KEEP = 3;

  const PATTERN_NON_PRINTABLE = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\x84\x86-\x9F\uFFFE\uFFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF]/;
  const PATTERN_NON_ASCII_LINE_BREAKS = /[\x85\u2028\u2029]/;
  const PATTERN_FLOW_INDICATORS = /[,\[\]\{\}]/;
  const PATTERN_TAG_HANDLE = /^(?:!|!!|![a-z\-]+!)$/i;
  const 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) {
    let lc;

    if (c /* 0 */ >= 0x30 && c <= 0x39 /* 9 */) {
      return c - 0x30;
    }

    /* eslint-disable no-bitwise */
    lc = c | 0x20;

    if (lc /* a */ >= 0x61 && 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 (c /* 0 */ >= 0x30 && 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
    );
  }

  const simpleEscapeCheck = new Array(256); // integer, for fast access
  const simpleEscapeMap = new Array(256);
  for (let 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) {
    const 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));
    }
  }

  const directiveHandlers = {
    YAML: function handleYamlDirective(state, name, args) {
      let match;
      let major;
      let 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) {
      let handle;
      let 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) {
    let _position;
    let _length;
    let _character;
    let _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 ||
              (_character >= 0x20 && _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) {
    let sourceKeys;
    let key;
    let index;
    let 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
  ) {
    let index;
    let 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) {
    let 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) {
    let lineBreaks = 0;
    let 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) {
    let _position = state.position;
    let 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) {
    let preceding;
    let following;
    let captureStart;
    let captureEnd;
    let hasPendingContent;
    let _line;
    let _lineStart;
    let _lineIndent;
    const _kind = state.kind;
    const _result = state.result;
    let 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) {
    let ch;
    let captureStart;
    let 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) {
    let captureStart;
    let captureEnd;
    let hexLength;
    let hexResult;
    let tmp;
    let 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) {
    let readNext = true;
    let _line;
    let _lineStart;
    let _pos;
    const _tag = state.tag;
    let _result;
    const _anchor = state.anchor;
    let following;
    let terminator;
    let isPair;
    let isExplicitPair;
    let isMapping;
    const overridableKeys = Object.create(null);
    let keyNode;
    let keyTag;
    let valueNode;
    let 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) {
    let captureStart;
    let folding;
    let chomping = CHOMPING_CLIP;
    let didReadContent = false;
    let detectedIndent = false;
    let textIndent = nodeIndent;
    let emptyLines = 0;
    let atMoreIndented = false;
    let tmp;
    let 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) {
    let _line;
    const _tag = state.tag;
    const _anchor = state.anchor;
    const _result = [];
    let following;
    let detected = false;
    let 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) {
    let following;
    let allowCompact;
    let _line;
    let _keyLine;
    let _keyLineStart;
    let _keyPos;
    const _tag = state.tag;
    const _anchor = state.anchor;
    const _result = {};
    const overridableKeys = Object.create(null);
    let keyTag = null;
    let keyNode = null;
    let valueNode = null;
    let atExplicitKey = false;
    let detected = false;
    let 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) {
    let _position;
    let isVerbatim = false;
    let isNamed = false;
    let tagHandle;
    let tagName;
    let 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) {
    let _position;
    let 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) {
    let _position;
    let alias;
    let 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
  ) {
    let allowBlockStyles;
    let allowBlockScalars;
    let allowBlockCollections;
    let indentStatus = 1; // 1: this>parent, 0: this=parent, -1: this<parent
    let atNewLine = false;
    let hasContent = false;
    let typeIndex;
    let typeQuantity;
    let typeList;
    let type;
    let flowIndent;
    let 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) {
    const documentStart = state.position;
    let _position;
    let directiveName;
    let directiveArgs;
    let hasDirectives = false;
    let 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 {
    }
  }

  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);
      }
    }

    const state = new State$1(input, options);

    const 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;
    }

    const documents = loadDocuments(input, options);

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

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

  function load$1(input, options) {
    const 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'
    );
  }

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

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

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

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

  const CHAR_BOM = 0xfeff;
  const CHAR_TAB = 0x09; /* Tab */
  const CHAR_LINE_FEED = 0x0a; /* LF */
  const CHAR_CARRIAGE_RETURN = 0x0d; /* CR */
  const CHAR_SPACE = 0x20; /* Space */
  const CHAR_EXCLAMATION = 0x21; /* ! */
  const CHAR_DOUBLE_QUOTE = 0x22; /* " */
  const CHAR_SHARP = 0x23; /* # */
  const CHAR_PERCENT = 0x25; /* % */
  const CHAR_AMPERSAND = 0x26; /* & */
  const CHAR_SINGLE_QUOTE = 0x27; /* ' */
  const CHAR_ASTERISK = 0x2a; /* * */
  const CHAR_COMMA = 0x2c; /* , */
  const CHAR_MINUS = 0x2d; /* - */
  const CHAR_COLON = 0x3a; /* : */
  const CHAR_EQUALS = 0x3d; /* = */
  const CHAR_GREATER_THAN = 0x3e; /* > */
  const CHAR_QUESTION = 0x3f; /* ? */
  const CHAR_COMMERCIAL_AT = 0x40; /* @ */
  const CHAR_LEFT_SQUARE_BRACKET = 0x5b; /* [ */
  const CHAR_RIGHT_SQUARE_BRACKET = 0x5d; /* ] */
  const CHAR_GRAVE_ACCENT = 0x60; /* ` */
  const CHAR_LEFT_CURLY_BRACKET = 0x7b; /* { */
  const CHAR_VERTICAL_LINE = 0x7c; /* | */
  const CHAR_RIGHT_CURLY_BRACKET = 0x7d; /* } */

  const 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';

  const DEPRECATED_BOOLEANS_SYNTAX = [
    'y',
    'Y',
    'yes',
    'Yes',
    'YES',
    'on',
    'On',
    'ON',
    'n',
    'N',
    'no',
    'No',
    'NO',
    'off',
    'Off',
    'OFF',
  ];

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

  function compileStyleMap(schema, map) {
    let result;
    let keys;
    let index;
    let length;
    let tag;
    let style;
    let 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) {
    let string;
    let handle;
    let 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}`;
  }

  const QUOTING_TYPE_SINGLE = 1;
  const 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) {
    const ind = common.repeat(' ', spaces);
    let position = 0;
    let next = -1;
    let result = '';
    let line;
    const { length } = string;

    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) {
    let index;
    let length;
    let 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 (
      (c >= 0x00020 && c <= 0x00007e) ||
      (c >= 0x000a1 && c <= 0x00d7ff && c !== 0x2028 && c !== 0x2029) ||
      (c >= 0x0e000 && c <= 0x00fffd && c !== CHAR_BOM) ||
      (c >= 0x10000 && 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) {
    const cIsNsCharOrWhitespace = isNsCharOrWhitespace(c);
    const 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) {
    const first = string.charCodeAt(pos);
    let 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) {
    const leadingSpaceRe = /^\n* /;
    return leadingSpaceRe.test(string);
  }

  const STYLE_PLAIN = 1;
  const STYLE_SINGLE = 2;
  const STYLE_LITERAL = 3;
  const STYLE_FOLDED = 4;
  const 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
  ) {
    let i;
    let char = 0;
    let prevChar = null;
    let hasLineBreak = false;
    let hasFoldableLine = false; // only checked if shouldTrackWidth
    const shouldTrackWidth = lineWidth !== -1;
    let previousLineBreak = -1; // count the first line correctly
    let 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}'`;
        }
      }

      const 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.
      const 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.
      const 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) {
    const indentIndicator = needIndentIndicator(string)
      ? String(indentPerLevel)
      : '';

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

    // first line (possibly an empty line)
    let result = (function() {
      let 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.
    let prevMoreIndented = string[0] === '\n' || string[0] === ' ';
    let moreIndented;

    // rest of the lines
    let match;
    while ((match = lineRe.exec(string))) {
      const prefix = match[1];
      const 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.
    const breakRe = / [^ ]/g; // note: the match index will always be <= length-2.
    let match;
    // start is an inclusive index. end, curr, and next are exclusive.
    let start = 0;
    let end;
    let curr = 0;
    let next = 0;
    let 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) {
    let result = '';
    let char = 0;
    let escapeSeq;

    for (let 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) {
    let _result = '';
    const _tag = state.tag;
    let index;
    let length;
    let 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) {
    let _result = '';
    const _tag = state.tag;
    let index;
    let length;
    let 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) {
    let _result = '';
    const _tag = state.tag;
    const objectKeyList = Object.keys(object);
    let index;
    let length;
    let objectKey;
    let objectValue;
    let 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) {
    let _result = '';
    const _tag = state.tag;
    const objectKeyList = Object.keys(object);
    let index;
    let length;
    let objectKey;
    let objectValue;
    let explicitPair;
    let 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) {
    let _result;
    let typeList;
    let index;
    let length;
    let type;
    let 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);
    }

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

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

    const objectOrArray =
      type === '[object Object]' || type === '[object Array]';
    let duplicateIndex;
    let 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) {
    const objects = [];
    const duplicatesIndexes = [];
    let index;
    let 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) {
    let objectKeyList;
    let index;
    let 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 || {};

    const state = new State(options);

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

    let value = input;

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

    if (writeNode(state, 0, value, true, true)) return `${state.dump}\n`;

    return '';
  }

  const dump_1 = dump$1;

  const 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.`
      );
    };
  }

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

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

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

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

  exports.CORE_SCHEMA = CORE_SCHEMA;
  exports.DEFAULT_SCHEMA = DEFAULT_SCHEMA;
  exports.FAILSAFE_SCHEMA = FAILSAFE_SCHEMA;
  exports.JSON_SCHEMA = JSON_SCHEMA;
  exports.Schema = Schema;
  exports.Type = Type;
  exports.YAMLException = YAMLException;
  exports.default = jsYaml;
  exports.dump = dump;
  exports.load = load;
  exports.loadAll = loadAll;
  exports.safeDump = safeDump;
  exports.safeLoad = safeLoad;
  exports.safeLoadAll = safeLoadAll;
  exports.types = types;

  Object.defineProperty(exports, '__esModule', { value: true });
});