es6.symbol.js

'use strict';
// ECMAScript 6 symbols shim
var global = require('./_global');
var has = require('./_has');
var DESCRIPTORS = require('./_descriptors');
var $export = require('./_export');
var redefine = require('./_redefine');
var META = require('./_meta').KEY;
var $fails = require('./_fails');
var shared = require('./_shared');
var setToStringTag = require('./_set-to-string-tag');
var uid = require('./_uid');
var wks = require('./_wks');
var wksExt = require('./_wks-ext');
var wksDefine = require('./_wks-define');
var enumKeys = require('./_enum-keys');
var isArray = require('./_is-array');
var anObject = require('./_an-object');
var toIObject = require('./_to-iobject');
var toPrimitive = require('./_to-primitive');
var createDesc = require('./_property-desc');
var _create = require('./_object-create');
var gOPNExt = require('./_object-gopn-ext');
var $GOPD = require('./_object-gopd');
var $DP = require('./_object-dp');
var $keys = require('./_object-keys');
var gOPD = $GOPD.f;
var dP = $DP.f;
var gOPN = gOPNExt.f;
var $Symbol = global.Symbol;
var $JSON = global.JSON;
var _stringify = $JSON && $JSON.stringify;
var PROTOTYPE = 'prototype';
var HIDDEN = wks('_hidden');
var TO_PRIMITIVE = wks('toPrimitive');
var isEnum = {}.propertyIsEnumerable;
var SymbolRegistry = shared('symbol-registry');
var AllSymbols = shared('symbols');
var OPSymbols = shared('op-symbols');
var ObjectProto = Object[PROTOTYPE];
var USE_NATIVE = typeof $Symbol == 'function';
var QObject = global.QObject;
// Don't use setters in Qt Script, https://github.com/zloirock/core-js/issues/173
var setter = !QObject || !QObject[PROTOTYPE] || !QObject[PROTOTYPE].findChild;

// fallback for old Android, https://code.google.com/p/v8/issues/detail?id=687
var setSymbolDesc = DESCRIPTORS && $fails(function () {
  return _create(dP({}, 'a', {
    get: function () { return dP(this, 'a', { value: 7 }).a; }
  })).a != 7;
}) ? function (it, key, D) {
  var protoDesc = gOPD(ObjectProto, key);
  if (protoDesc) delete ObjectProto[key];
  dP(it, key, D);
  if (protoDesc && it !== ObjectProto) dP(ObjectProto, key, protoDesc);
} : dP;

var wrap = function (tag) {
  var sym = AllSymbols[tag] = _create($Symbol[PROTOTYPE]);
  sym._k = tag;
  return sym;
};

var isSymbol = USE_NATIVE && typeof $Symbol.iterator == 'symbol' ? function (it) {
  return typeof it == 'symbol';
} : function (it) {
  return it instanceof $Symbol;
};

var $defineProperty = function defineProperty(it, key, D) {
  if (it === ObjectProto) $defineProperty(OPSymbols, key, D);
  anObject(it);
  key = toPrimitive(key, true);
  anObject(D);
  if (has(AllSymbols, key)) {
    if (!D.enumerable) {
      if (!has(it, HIDDEN)) dP(it, HIDDEN, createDesc(1, {}));
      it[HIDDEN][key] = true;
    } else {
      if (has(it, HIDDEN) && it[HIDDEN][key]) it[HIDDEN][key] = false;
      D = _create(D, { enumerable: createDesc(0, false) });
    } return setSymbolDesc(it, key, D);
  } return dP(it, key, D);
};
var $defineProperties = function defineProperties(it, P) {
  anObject(it);
  var keys = enumKeys(P = toIObject(P));
  var i = 0;
  var l = keys.length;
  var key;
  while (l > i) $defineProperty(it, key = keys[i++], P[key]);
  return it;
};
var $create = function create(it, P) {
  return P === undefined ? _create(it) : $defineProperties(_create(it), P);
};
var $propertyIsEnumerable = function propertyIsEnumerable(key) {
  var E = isEnum.call(this, key = toPrimitive(key, true));
  if (this === ObjectProto && has(AllSymbols, key) && !has(OPSymbols, key)) return false;
  return E || !has(this, key) || !has(AllSymbols, key) || has(this, HIDDEN) && this[HIDDEN][key] ? E : true;
};
var $getOwnPropertyDescriptor = function getOwnPropertyDescriptor(it, key) {
  it = toIObject(it);
  key = toPrimitive(key, true);
  if (it === ObjectProto && has(AllSymbols, key) && !has(OPSymbols, key)) return;
  var D = gOPD(it, key);
  if (D && has(AllSymbols, key) && !(has(it, HIDDEN) && it[HIDDEN][key])) D.enumerable = true;
  return D;
};
var $getOwnPropertyNames = function getOwnPropertyNames(it) {
  var names = gOPN(toIObject(it));
  var result = [];
  var i = 0;
  var key;
  while (names.length > i) {
    if (!has(AllSymbols, key = names[i++]) && key != HIDDEN && key != META) result.push(key);
  } return result;
};
var $getOwnPropertySymbols = function getOwnPropertySymbols(it) {
  var IS_OP = it === ObjectProto;
  var names = gOPN(IS_OP ? OPSymbols : toIObject(it));
  var result = [];
  var i = 0;
  var key;
  while (names.length > i) {
    if (has(AllSymbols, key = names[i++]) && (IS_OP ? has(ObjectProto, key) : true)) result.push(AllSymbols[key]);
  } return result;
};

// 19.4.1.1 Symbol([description])
if (!USE_NATIVE) {
  $Symbol = function Symbol() {
    if (this instanceof $Symbol) throw TypeError('Symbol is not a constructor!');
    var tag = uid(arguments.length > 0 ? arguments[0] : undefined);
    var $set = function (value) {
      if (this === ObjectProto) $set.call(OPSymbols, value);
      if (has(this, HIDDEN) && has(this[HIDDEN], tag)) this[HIDDEN][tag] = false;
      setSymbolDesc(this, tag, createDesc(1, value));
    };
    if (DESCRIPTORS && setter) setSymbolDesc(ObjectProto, tag, { configurable: true, set: $set });
    return wrap(tag);
  };
  redefine($Symbol[PROTOTYPE], 'toString', function toString() {
    return this._k;
  });

  $GOPD.f = $getOwnPropertyDescriptor;
  $DP.f = $defineProperty;
  require('./_object-gopn').f = gOPNExt.f = $getOwnPropertyNames;
  require('./_object-pie').f = $propertyIsEnumerable;
  require('./_object-gops').f = $getOwnPropertySymbols;

  if (DESCRIPTORS && !require('./_library')) {
    redefine(ObjectProto, 'propertyIsEnumerable', $propertyIsEnumerable, true);
  }

  wksExt.f = function (name) {
    return wrap(wks(name));
  };
}

$export($export.G + $export.W + $export.F * !USE_NATIVE, { Symbol: $Symbol });

for (var es6Symbols = (
  // 19.4.2.2, 19.4.2.3, 19.4.2.4, 19.4.2.6, 19.4.2.8, 19.4.2.9, 19.4.2.10, 19.4.2.11, 19.4.2.12, 19.4.2.13, 19.4.2.14
  'hasInstance,isConcatSpreadable,iterator,match,replace,search,species,split,toPrimitive,toStringTag,unscopables'
).split(','), j = 0; es6Symbols.length > j;)wks(es6Symbols[j++]);

for (var wellKnownSymbols = $keys(wks.store), k = 0; wellKnownSymbols.length > k;) wksDefine(wellKnownSymbols[k++]);

$export($export.S + $export.F * !USE_NATIVE, 'Symbol', {
  // 19.4.2.1 Symbol.for(key)
  'for': function (key) {
    return has(SymbolRegistry, key += '')
      ? SymbolRegistry[key]
      : SymbolRegistry[key] = $Symbol(key);
  },
  // 19.4.2.5 Symbol.keyFor(sym)
  keyFor: function keyFor(sym) {
    if (!isSymbol(sym)) throw TypeError(sym + ' is not a symbol!');
    for (var key in SymbolRegistry) if (SymbolRegistry[key] === sym) return key;
  },
  useSetter: function () { setter = true; },
  useSimple: function () { setter = false; }
});

$export($export.S + $export.F * !USE_NATIVE, 'Object', {
  // 19.1.2.2 Object.create(O [, Properties])
  create: $create,
  // 19.1.2.4 Object.defineProperty(O, P, Attributes)
  defineProperty: $defineProperty,
  // 19.1.2.3 Object.defineProperties(O, Properties)
  defineProperties: $defineProperties,
  // 19.1.2.6 Object.getOwnPropertyDescriptor(O, P)
  getOwnPropertyDescriptor: $getOwnPropertyDescriptor,
  // 19.1.2.7 Object.getOwnPropertyNames(O)
  getOwnPropertyNames: $getOwnPropertyNames,
  // 19.1.2.8 Object.getOwnPropertySymbols(O)
  getOwnPropertySymbols: $getOwnPropertySymbols
});

// 24.3.2 JSON.stringify(value [, replacer [, space]])
$JSON && $export($export.S + $export.F * (!USE_NATIVE || $fails(function () {
  var S = $Symbol();
  // MS Edge converts symbol values to JSON as {}
  // WebKit converts symbol values to JSON as null
  // V8 throws on boxed symbols
  return _stringify([S]) != '[null]' || _stringify({ a: S }) != '{}' || _stringify(Object(S)) != '{}';
})), 'JSON', {
  stringify: function stringify(it) {
    if (it === undefined || isSymbol(it)) return; // IE8 returns string on undefined
    var args = [it];
    var i = 1;
    var replacer, $replacer;
    while (arguments.length > i) args.push(arguments[i++]);
    replacer = args[1];
    if (typeof replacer == 'function') $replacer = replacer;
    if ($replacer || !isArray(replacer)) replacer = function (key, value) {
      if ($replacer) value = $replacer.call(this, key, value);
      if (!isSymbol(value)) return value;
    };
    args[1] = replacer;
    return _stringify.apply($JSON, args);
  }
});

// 19.4.3.4 Symbol.prototype[@@toPrimitive](hint)
$Symbol[PROTOTYPE][TO_PRIMITIVE] || require('./_hide')($Symbol[PROTOTYPE], TO_PRIMITIVE, $Symbol[PROTOTYPE].valueOf);
// 19.4.3.5 Symbol.prototype[@@toStringTag]
setToStringTag($Symbol, 'Symbol');
// 20.2.1.9 Math[@@toStringTag]
setToStringTag(Math, 'Math', true);
// 24.3.3 JSON[@@toStringTag]
setToStringTag(global.JSON, 'JSON', true);