- Author:
- David Nickerson <nickerso@users.sourceforge.net>
- Date:
- 2009-07-16 02:00:03+12:00
- Desc:
- the starting point for the HH tutorial example
- Permanent Source URI:
- https://models.fieldml.org/workspace/a1/rawfile/f6a8f90307388eb4b040ee3566b84d88b59247f7/dojo-presentation/js/dojo/dojox/lang/aspect.js
dojo.provide("dojox.lang.aspect");
(function(){
var d = dojo, aop = dojox.lang.aspect, ap = Array.prototype,
contextStack = [], context;
// this class implements a topic-based double-linked list
var Advice = function(){
this.next_before = this.prev_before =
this.next_around = this.prev_around =
this.next_afterReturning = this.prev_afterReturning =
this.next_afterThrowing = this.prev_afterThrowing =
this;
this.counter = 0;
};
d.extend(Advice, {
add: function(advice){
var dyn = d.isFunction(advice),
node = {advice: advice, dynamic: dyn};
this._add(node, "before", "", dyn, advice);
this._add(node, "around", "", dyn, advice);
this._add(node, "after", "Returning", dyn, advice);
this._add(node, "after", "Throwing", dyn, advice);
++this.counter;
return node;
},
_add: function(node, topic, subtopic, dyn, advice){
var full = topic + subtopic;
if(dyn || advice[topic] || (subtopic && advice[full])){
var next = "next_" + full, prev = "prev_" + full;
(node[prev] = this[prev])[next] = node;
(node[next] = this)[prev] = node;
}
},
remove: function(node){
this._remove(node, "before");
this._remove(node, "around");
this._remove(node, "afterReturning");
this._remove(node, "afterThrowing");
--this.counter;
},
_remove: function(node, topic){
var next = "next_" + topic, prev = "prev_" + topic;
if(node[next]){
node[next][prev] = node[prev];
node[prev][next] = node[next];
}
},
isEmpty: function(){
return !this.counter;
}
});
var getDispatcher = function(){
return function(){
var self = arguments.callee, // the join point
advices = self.advices, // list of advices for this joinpoint
ret, i, a, e, t;
// push context
if(context){ contextStack.push(context); }
context = {
instance: this, // object instance
joinPoint: self, // join point
depth: contextStack.length, // current level of depth starting from 0
around: advices.prev_around, // pointer to the current around advice
dynAdvices: [], // array of dynamic advices if any
dynIndex: 0 // index of a dynamic advice
};
try{
// process before events
for(i = advices.prev_before; i != advices; i = i.prev_before){
if(i.dynamic){
// instantiate a dynamic advice
context.dynAdvices.push(a = new i.advice(context));
if(t = a.before){
t.apply(a, arguments);
}
}else{
t = i.advice;
t.before.apply(t, arguments);
}
}
// process around and after events
try{
// call the around advice or the original method
ret = (advices.prev_around == advices ? self.target : aop.proceed).apply(this, arguments);
}catch(e){
// process after throwing and after events
context.dynIndex = context.dynAdvices.length;
for(i = advices.next_afterThrowing; i != advices; i = i.next_afterThrowing){
a = i.dynamic ? context.dynAdvices[--context.dynIndex] : i.advice;
if(t = a.afterThrowing){
t.call(a, e);
}
if(t = a.after){
t.call(a);
}
}
// continue the exception processing
throw e;
}
// process after returning and after events
context.dynIndex = context.dynAdvices.length;
for(i = advices.next_afterReturning; i != advices; i = i.next_afterReturning){
a = i.dynamic ? context.dynAdvices[--context.dynIndex] : i.advice;
if(t = a.afterReturning){
t.call(a, ret);
}
if(t = a.after){
t.call(a);
}
}
// process dojo.connect() listeners
var ls = self._listeners;
for(i in ls){
if(!(i in ap)){
ls[i].apply(this, arguments);
}
}
}finally{
// destroy dynamic advices
for(i = 0; i < context.dynAdvices.length; ++i){
a = context.dynAdvices[i];
if(a.destroy){
a.destroy();
}
}
// pop context
context = contextStack.length ? contextStack.pop() : null;
}
return ret;
};
};
aop.advise = function(/*Object*/ obj,
/*String|RegExp|Array*/ method,
/*Object|Function|Array*/ advice
){
// summary:
// Attach AOP-style advices to a method.
//
// description:
// Attaches AOP-style advices to a method. Can attach several
// advices at once and operate on several methods of an object.
// The latter is achieved when a RegExp is specified as
// a method name, or an array of strings and regular expressions
// is used. In this case all functional methods that
// satisfy the RegExp condition are processed. This function
// returns a handle, which can be used to unadvise, or null,
// if advising has failed.
//
// This function is a convenience wrapper for
// dojox.lang.aspect.adviseRaw().
//
// obj:
// A source object for the advised function. Cannot be a DOM node.
// If this object is a constructor, its prototype is advised.
//
// method:
// A string name of the function in obj. In case of RegExp all
// methods of obj matching the regular expression are advised.
//
// advice:
// An object, which defines advises, or a function, which
// returns such object, or an array of previous items.
// The advice object can define following member functions:
// before, around, afterReturning, afterThrowing, after.
// If the function is supplied, it is called with a context
// object once per call to create a temporary advice object, which
// is destroyed after the processing. The temporary advice object
// can implement a destroy() method, if it wants to be called when
// not needed.
if(typeof obj != "object"){
obj = obj.prototype;
}
var methods = [];
if(!(method instanceof Array)){
method = [method];
}
// identify advised methods
for(var j = 0; j < method.length; ++j){
var t = method[j];
if(t instanceof RegExp){
for(var i in obj){
if(d.isFunction(obj[i]) && t.test(i)){
methods.push(i);
}
}
}else{
if(d.isFunction(obj[t])){
methods.push(t);
}
}
}
if(!d.isArray(advice)){ advice = [advice]; }
return aop.adviseRaw(obj, methods, advice); // Object
};
aop.adviseRaw = function(/*Object*/ obj,
/*Array*/ methods,
/*Array*/ advices
){
// summary:
// Attach AOP-style advices to methods.
//
// description:
// Attaches AOP-style advices to object's methods. Can attach several
// advices at once and operate on several methods of the object.
// The latter is achieved when a RegExp is specified as
// a method name. In this case all functional methods that
// satisfy the RegExp condition are processed. This function
// returns a handle, which can be used to unadvise, or null,
// if advising has failed.
//
// obj:
// A source object for the advised function.
// Cannot be a DOM node.
//
// methods:
// An array of method names (strings) to be advised.
//
// advices:
// An array of advices represented by objects or functions that
// return such objects on demand during the event processing.
// The advice object can define following member functions:
// before, around, afterReturning, afterThrowing, after.
// If the function is supplied, it is called with a context
// object once per call to create a temporary advice object, which
// is destroyed after the processing. The temporary advice object
// can implement a destroy() method, if it wants to be called when
// not needed.
if(!methods.length || !advices.length){ return null; }
// attach advices
var m = {}, al = advices.length;
for(var i = methods.length - 1; i >= 0; --i){
var name = methods[i], o = obj[name], ao = new Array(al), t = o.advices;
// create a stub, if needed
if(!t){
var x = obj[name] = getDispatcher();
x.target = o.target || o;
x.targetName = name;
x._listeners = o._listeners || [];
x.advices = new Advice;
t = x.advices;
}
// attach advices
for(var j = 0; j < al; ++j){
ao[j] = t.add(advices[j]);
}
m[name] = ao;
}
return [obj, m]; // Object
};
aop.unadvise = function(/*Object*/ handle){
// summary:
// Detach previously attached AOP-style advices.
//
// handle:
// The object returned by dojox.lang.aspect.advise().
if(!handle){ return; }
var obj = handle[0], methods = handle[1];
for(var name in methods){
var o = obj[name], t = o.advices, ao = methods[name];
for(var i = ao.length - 1; i >= 0; --i){
t.remove(ao[i]);
}
if(t.isEmpty()){
// check if we can remove all stubs
var empty = true, ls = o._listeners;
if(ls.length){
for(i in ls){
if(!(i in ap)){
empty = false;
break;
}
}
}
if(empty){
// revert to the original method
obj[name] = o.target;
}else{
// replace with the dojo.connect() stub
var x = obj[name] = d._listener.getDispatcher();
x.target = o.target;
x._listeners = ls;
}
}
}
};
aop.getContext = function(){
// summary:
// Returns the context information for the advice in effect.
return context; // Object
};
aop.getContextStack = function(){
// summary:
// Returns the context stack, which reflects executing advices
// up to this point. The array is ordered from oldest to newest.
// In order to get the active context use dojox.lang.aspect.getContext().
return contextStack; // Array
};
aop.proceed = function(){
// summary:
// Call the original function (or the next level around advice) in an around advice code.
//
// description:
// Calls the original function (or the next level around advice).
// Accepts and passes on any number of arguments, and returns a value.
// This function is valid only in the content of around calls.
var joinPoint = context.joinPoint, advices = joinPoint.advices;
for(var c = context.around; c != advices; c = context.around){
context.around = c.prev_around; // advance the pointer
if(c.dynamic){
var a = context.dynAdvices[context.dynIndex++], t = a.around;
if(t){
return t.apply(a, arguments);
}
}else{
return c.advice.around.apply(c.advice, arguments);
}
}
return joinPoint.target.apply(context.instance, arguments);
};
})();
/*
Aspect = {
before: function(arguments){...},
around: function(arguments){...returns value...},
afterReturning: function(ret){...},
afterThrowing: function(excp){...},
after: function(){...}
};
Context = {
instance: ..., // the instance we operate on
joinPoint: ..., // Object (see below)
depth: ... // current depth of the context stack
};
JoinPoint = {
target: ..., // the original function being wrapped
targetName: ... // name of the method
};
*/
