es6.weak-map.js

'use strict';
var each         = require('./_array-methods')(0)
  , redefine     = require('./_redefine')
  , meta         = require('./_meta')
  , assign       = require('./_object-assign')
  , weak         = require('./_collection-weak')
  , isObject     = require('./_is-object')
  , has          = require('./_has')
  , getWeak      = meta.getWeak
  , isExtensible = Object.isExtensible
  , uncaughtFrozenStore = weak.ufstore
  , tmp          = {}
  , InternalMap;

var wrapper = function(get){
  return function WeakMap(){
    return get(this, arguments.length > 0 ? arguments[0] : undefined);
  };
};

var methods = {
  // 23.3.3.3 WeakMap.prototype.get(key)
  get: function get(key){
    if(isObject(key)){
      var data = getWeak(key);
      if(data === true)return uncaughtFrozenStore(this).get(key);
      return data ? data[this._i] : undefined;
    }
  },
  // 23.3.3.5 WeakMap.prototype.set(key, value)
  set: function set(key, value){
    return weak.def(this, key, value);
  }
};

// 23.3 WeakMap Objects
var $WeakMap = module.exports = require('./_collection')('WeakMap', wrapper, methods, weak, true, true);

// IE11 WeakMap frozen keys fix
if(new $WeakMap().set((Object.freeze || Object)(tmp), 7).get(tmp) != 7){
  InternalMap = weak.getConstructor(wrapper);
  assign(InternalMap.prototype, methods);
  meta.NEED = true;
  each(['delete', 'has', 'get', 'set'], function(key){
    var proto  = $WeakMap.prototype
      , method = proto[key];
    redefine(proto, key, function(a, b){
      // store frozen objects on internal weakmap shim
      if(isObject(a) && !isExtensible(a)){
        if(!this._f)this._f = new InternalMap;
        var result = this._f[key](a, b);
        return key == 'set' ? this : result;
      // store all the rest on native weakmap
      } return method.call(this, a, b);
    });
  });
}