initial commit

node_modules/es6-symbol/polyfill.js

@@ -0,0 +1,118 @@
+// ES2015 Symbol polyfill for environments that do not (or partially) support it
+
+'use strict';
+
+var d              = require('d')
+  , validateSymbol = require('./validate-symbol')
+
+  , create = Object.create, defineProperties = Object.defineProperties
+  , defineProperty = Object.defineProperty, objPrototype = Object.prototype
+  , NativeSymbol, SymbolPolyfill, HiddenSymbol, globalSymbols = create(null)
+  , isNativeSafe;
+
+if (typeof Symbol === 'function') {
+	NativeSymbol = Symbol;
+	try {
+		String(NativeSymbol());
+		isNativeSafe = true;
+	} catch (ignore) {}
+}
+
+var generateName = (function () {
+	var created = create(null);
+	return function (desc) {
+		var postfix = 0, name, ie11BugWorkaround;
+		while (created[desc + (postfix || '')]) ++postfix;
+		desc += (postfix || '');
+		created[desc] = true;
+		name = '@@' + desc;
+		defineProperty(objPrototype, name, d.gs(null, function (value) {
+			// For IE11 issue see:
+			// https://connect.microsoft.com/IE/feedbackdetail/view/1928508/
+			//    ie11-broken-getters-on-dom-objects
+			// https://github.com/medikoo/es6-symbol/issues/12
+			if (ie11BugWorkaround) return;
+			ie11BugWorkaround = true;
+			defineProperty(this, name, d(value));
+			ie11BugWorkaround = false;
+		}));
+		return name;
+	};
+}());
+
+// Internal constructor (not one exposed) for creating Symbol instances.
+// This one is used to ensure that `someSymbol instanceof Symbol` always return false
+HiddenSymbol = function Symbol(description) {
+	if (this instanceof HiddenSymbol) throw new TypeError('Symbol is not a constructor');
+	return SymbolPolyfill(description);
+};
+
+// Exposed `Symbol` constructor
+// (returns instances of HiddenSymbol)
+module.exports = SymbolPolyfill = function Symbol(description) {
+	var symbol;
+	if (this instanceof Symbol) throw new TypeError('Symbol is not a constructor');
+	if (isNativeSafe) return NativeSymbol(description);
+	symbol = create(HiddenSymbol.prototype);
+	description = (description === undefined ? '' : String(description));
+	return defineProperties(symbol, {
+		__description__: d('', description),
+		__name__: d('', generateName(description))
+	});
+};
+defineProperties(SymbolPolyfill, {
+	for: d(function (key) {
+		if (globalSymbols[key]) return globalSymbols[key];
+		return (globalSymbols[key] = SymbolPolyfill(String(key)));
+	}),
+	keyFor: d(function (s) {
+		var key;
+		validateSymbol(s);
+		for (key in globalSymbols) if (globalSymbols[key] === s) return key;
+	}),
+
+	// To ensure proper interoperability with other native functions (e.g. Array.from)
+	// fallback to eventual native implementation of given symbol
+	hasInstance: d('', (NativeSymbol && NativeSymbol.hasInstance) || SymbolPolyfill('hasInstance')),
+	isConcatSpreadable: d('', (NativeSymbol && NativeSymbol.isConcatSpreadable) ||
+		SymbolPolyfill('isConcatSpreadable')),
+	iterator: d('', (NativeSymbol && NativeSymbol.iterator) || SymbolPolyfill('iterator')),
+	match: d('', (NativeSymbol && NativeSymbol.match) || SymbolPolyfill('match')),
+	replace: d('', (NativeSymbol && NativeSymbol.replace) || SymbolPolyfill('replace')),
+	search: d('', (NativeSymbol && NativeSymbol.search) || SymbolPolyfill('search')),
+	species: d('', (NativeSymbol && NativeSymbol.species) || SymbolPolyfill('species')),
+	split: d('', (NativeSymbol && NativeSymbol.split) || SymbolPolyfill('split')),
+	toPrimitive: d('', (NativeSymbol && NativeSymbol.toPrimitive) || SymbolPolyfill('toPrimitive')),
+	toStringTag: d('', (NativeSymbol && NativeSymbol.toStringTag) || SymbolPolyfill('toStringTag')),
+	unscopables: d('', (NativeSymbol && NativeSymbol.unscopables) || SymbolPolyfill('unscopables'))
+});
+
+// Internal tweaks for real symbol producer
+defineProperties(HiddenSymbol.prototype, {
+	constructor: d(SymbolPolyfill),
+	toString: d('', function () { return this.__name__; })
+});
+
+// Proper implementation of methods exposed on Symbol.prototype
+// They won't be accessible on produced symbol instances as they derive from HiddenSymbol.prototype
+defineProperties(SymbolPolyfill.prototype, {
+	toString: d(function () { return 'Symbol (' + validateSymbol(this).__description__ + ')'; }),
+	valueOf: d(function () { return validateSymbol(this); })
+});
+defineProperty(SymbolPolyfill.prototype, SymbolPolyfill.toPrimitive, d('', function () {
+	var symbol = validateSymbol(this);
+	if (typeof symbol === 'symbol') return symbol;
+	return symbol.toString();
+}));
+defineProperty(SymbolPolyfill.prototype, SymbolPolyfill.toStringTag, d('c', 'Symbol'));
+
+// Proper implementaton of toPrimitive and toStringTag for returned symbol instances
+defineProperty(HiddenSymbol.prototype, SymbolPolyfill.toStringTag,
+	d('c', SymbolPolyfill.prototype[SymbolPolyfill.toStringTag]));
+
+// Note: It's important to define `toPrimitive` as last one, as some implementations
+// implement `toPrimitive` natively without implementing `toStringTag` (or other specified symbols)
+// And that may invoke error in definition flow:
+// See: https://github.com/medikoo/es6-symbol/issues/13#issuecomment-164146149
+defineProperty(HiddenSymbol.prototype, SymbolPolyfill.toPrimitive,
+	d('c', SymbolPolyfill.prototype[SymbolPolyfill.toPrimitive]));