betajs/betajs-shims

(function() {
    if (this.Map !== undefined)
        return;

    this.Map = function() {
        this.clear();
    };

    this.Map.prototype.set = function(key, value) {
        if (key in this.__data)
            this.__data[key].value = value;
        else {
            var obj = {
                key : key,
                value : value,
                prev : this.__last,
                next : null
            };
            this.__data[key] = obj;
            if (this.__last)
                this.__last.next = obj;
            else
                this.__first = obj;
            this.__last = obj;
            this.size++;
        }
        return this;
    };

    this.Map.prototype.get = function(key) {
        return key in this.__data ? this.__data[key].value : undefined;
    };

    this.Map.prototype.has = function(key) {
        return key in this.__data;
    };

    this.Map.prototype['delete'] = function(key) {
        var obj = this.__data[key];
        if (obj) {
            delete this.__data[key];
            this.size--;
            if (obj.prev)
                obj.prev.next = obj.next;
            else
                this.__first = obj.next;
            if (obj.next)
                obj.next.prev = obj.prev;
            else
                this.__last = obj.prev;
        }
        return this;
    };

    this.Map.prototype.clear = function() {
        this.__data = {};
        this.__first = null;
        this.__last = null;
        this.size = 0;
        return this;
    };

    this.Map.prototype.keys = function() {
        return {
            current : this.__first,
            next : function() {
                var current = this.current;
                if (!current)
                    return {
                        done : true
                    };
                this.current = current.next;
                return {
                    done : false,
                    value : current.key
                };
            }
        };
    };

    this.Map.prototype.values = function() {
        return {
            current : this.__first,
            next : function() {
                var current = this.current;
                if (!current)
                    return {
                        done : true
                    };
                this.current = current.next;
                return {
                    done : false,
                    value : current.value
                };
            }
        };
    };

    this.Map.prototype.entries = function() {
        return {
            current : this.__first,
            next : function() {
                var current = this.current;
                if (!current)
                    return {
                        done : true
                    };
                this.current = current.next;
                return {
                    done : false,
                    value : [ current.key, current.value ]
                };
            }
        };
    };

    this.Map.prototype.forEach = function(callback, context) {
        var current = this.__first;
        while (current) {
            callback.call(context, current.value, current.key, this);
            current = current.next;
        }
        return this;
    };

}).call((function () {
    try {
        return window;
    } catch (e) {
        try {
            return global;
        } catch (e) {
            return self;
        }
    }
}).call(this));