set.js

function Set(hashFunction) {
	this._hashFunction = hashFunction || JSON.stringify;
	this._values = {};
	this._size = 0;
}

Set.prototype = {
	add: function add(value) {
		if (!this.contains(value)) {
			this._values[this._hashFunction(value)] = value;
			this._size++;
		}
	},
	
	remove: function remove(value) {
		if (this.contains(value)) {
			delete this._values[this._hashFunction(value)];
			this._size--;
		}
	},
	
	contains: function contains(value) {
		return typeof this._values[this._hashFunction(value)] !== "undefined";
	},
	
	size: function size() {
		return this._size;
	},
	
	each: function each(iteratorFunction, thisObj) {
		for (var value in this._values) {
			iteratorFunction.call(thisObj, this._values[value]);
		}
	}
};