advise.js

(function(factory){
	if(typeof define != "undefined"){
		define([], factory);
	}else if(typeof module != "undefined"){
		module.exports = factory();
	}else{
		advise = factory();
	}
})(function(){
	"use strict";

	function Node(instance, name){
		this.nb = this.pb = this.na = this.pa = this.nf = this.pf = this;
		this.i = instance;
		this.n = name;
	}
	var p = Node.prototype = {
		a: function(b, a, f, o){
			var t = new Node(this.i, this.n);
			t.p = this;
			t.b = b;
			this._a("b", t);
			t.a = a;
			this._a("a", t);
			t.f = f;
			this._a("f", t, o);
			t.o = o;
			if(o){ t.f = advise._f(o, t.pf.f, this); }
			return t;
		},
		_a: function(topic, node, flag){
			if(node[topic] || flag){
				var n = "n" + topic, p = "p" + topic;
				(node[p] = this[p])[n] = (node[n] = this)[p] = node;
			}
		},
		r: function(node){
			this._r("b", node);
			this._r("a", node);
			this._r("f", node);
		},
		_r: function(topic, node){
			var n = "n" + topic, p = "p" + topic;
			node[n][p] = node[p];
			node[p][n] = node[n];
		},
		destroy: function(){
			var f = this.pf.f, t = this.nf, p = this.p;
			this.r(this);
			if(t !== this){
				for(; t !== p; f = t.f, t = t.nf){
					if(t.o){
						t.f = advise._f(t.o, f, this);
					}
				}
			}
			this.i = 0;
		}
	};
	p.unadvise = p.destroy;   // alias

	function makeAOPStub(x){
		var f = function(){
			var p, r, t = this, a = arguments;
			// running the before chain
			for(p = x.pb; p !== x; p = p.pb){
				p.b.apply(t, a);
			}
			// running the around chain
			try{
				if(x.pf !== x){ r = x.pf.f.apply(t, a); }
			}catch(e){
				r = e;
			}
			// running the after chain
			for(p = x.na; p !== x; p = p.na){
				p.a.call(t, a, r);
			}
			if(r instanceof Error){
				throw r;
			}
			return r;
		};
		f.adviceNode = x;
		return f;
	}

	function advise(instance, name, advice){
		var f = instance[name], a;
		if(f && f.adviceNode && f.adviceNode instanceof Node){
			a = f.adviceNode;
		}else{
			a = new Node(instance, name);
			if(f && f.advices){
				f = f.advices;
				a.a(f.b, f.a, f.f);
			}else{
				a.a(0, 0, f);
			}
			instance[name] = makeAOPStub(a);
		}
		if(typeof advice == "function"){ advice = advice(name, instance); }
		return a.a(advice.before, advice.after, 0, advice.around);
	}

	advise.before = function(instance, name, f){ return advise(instance, name, {before: f}); };
	advise.after  = function(instance, name, f){ return advise(instance, name, {after: f}); };
	advise.around = function(instance, name, f){ return advise(instance, name, {around: f}); };
	advise.Node = Node;

	advise._f = function(f, a, node){ return f(a); };

	return advise;
});