es6.weak-map.js

'use strict';
var $            = require('./$')
  , redefine     = require('./$.redefine')
  , weak         = require('./$.collection-weak')
  , isObject     = require('./$.is-object')
  , has          = require('./$.has')
  , frozenStore  = weak.frozenStore
  , WEAK         = weak.WEAK
  , isExtensible = Object.isExtensible || isObject
  , tmp          = {};

// 23.3 WeakMap Objects
var $WeakMap = require('./$.collection')('WeakMap', function(get){
  return function WeakMap(){ return get(this, arguments.length > 0 ? arguments[0] : undefined); };
}, {
  // 23.3.3.3 WeakMap.prototype.get(key)
  get: function get(key){
    if(isObject(key)){
      if(!isExtensible(key))return frozenStore(this).get(key);
      if(has(key, WEAK))return key[WEAK][this._i];
    }
  },
  // 23.3.3.5 WeakMap.prototype.set(key, value)
  set: function set(key, value){
    return weak.def(this, key, value);
  }
}, weak, true, true);

// IE11 WeakMap frozen keys fix
if(new $WeakMap().set((Object.freeze || Object)(tmp), 7).get(tmp) != 7){
  $.each.call(['delete', 'has', 'get', 'set'], function(key){
    var proto  = $WeakMap.prototype
      , method = proto[key];
    redefine(proto, key, function(a, b){
      // store frozen objects on leaky map
      if(isObject(a) && !isExtensible(a)){
        var result = frozenStore(this)[key](a, b);
        return key == 'set' ? this : result;
      // store all the rest on native weakmap
      } return method.call(this, a, b);
    });
  });
}