delegation with tests as string, function, or array

/*
Script: Element.Delegate.js
	Extends the Element native object to include the delegate method for more efficient event management.

License:
	http://www.clientcide.com/wiki/cnet-libraries#license
*/
(function(){
	
	var getType = function(type) {
		if ($type(type) != "string") return type;
		var custom = Element.Events.get(type);
		return custom ? custom.base : type;
	};

	var checkOverOut = function(el, e){
		if (el == e.target || el.hasChild(e.target)) {
			var related = e.relatedTarget;
			if (related == undefined) return true;
			if (related === false) return false;
			return ($type(el) != 'document' && related != el && related.prefix != 'xul' && !el.hasChild(related));
		}
	};
	
	function check(e, test) {
		var target = e.target;
		var isOverOut = /^(mouseover|mouseout)$/.test(e.type);
		var els;
		if ($type(test) == 'string') els = this.getElements(test);
		else if ($type(test) == 'array') els = test;
		var match = els.indexOf(target);
		if (match >= 0) return els[match];
		for (var i = els.length; i--; ) {
			var el = els[i];
			if (el == target || el.hasChild(target)) {
				return (!isOverOut || checkOverOut(el, e)) ? el : false;
			}
		}
	}

	
	Element.implement({

		delegate: function(test, type, fn) {
			if ($type(type) == 'object') {
				$each(type, function(f, t) {
					this.delegate(test, t, f);
				}, this)
				return this;
			}
			type = getType(type);
			var isOverOut = /^(mouseover|mouseout)$/.test(type);
			
			var fns = this.retrieve('delegates', []);
			fns.push(fn);
			var wraps = this.retrieve('delegations', []);
			var tester;
			switch($type(test)) {
				case 'string':
					tester = function(e) {
						return check.call(this, e, test);
					}.bind(this); break;
				case 'function':
					tester = test; break;
				case 'array':
					tester = function(e) {
						return check.call(this, e, test);
					}.bind(this); break;
			}
			var wrapper = function(e) { var el = tester(e); if (el) fn.call(el, e, el);	};
			wraps.push(wrapper);
			return this.addEvent(type, wrapper);
		},
		unDelegate: function(type, fn) {
			var fns = this.retrieve('delegates', []);
			var index = fns.indexOf(fn);
			if (index == -1) return this;
			var wraps = this.retrieve('delegations', []);
			var fn = wraps[index];
			if (!fn) return this;
			wraps.splice(index, 1);
			fns.splice(index, 1);
			this.store('delegations', wraps).store('delegates', fns);
			return this.removeEvent(getType(type), fn);
		}
	});
})();