今天从GIT源码库中下载了promise.js，发现该源码是基于Web前端JavaScript写的，并不能直接用于nodejs。还好代码不是很多，也不是很复杂。经过分析整合，将其实现为nodejs的一个框架，代码如下：
(function(){
/**
* Copyright 2012-2013 (c) Pierre Duquesne <stackp@online.fr>
* script: promise.js
* description: promises的nodejs模块
* modified: https://github.com/stackp/promisejs
* authors: alwu007@sina.cn
* */
var Promise = exports.Promise = function(){
this._callbacks = [];
};
Promise.prototype.then = function(func, context){
//处理回调结果的方法
function doCallbackResults(r) {
if (r instanceof Promise) {
r.then(function(err, values){
p.done(err, values);
});
} else {
p.done(null, r);
}
}
var p = new Promise();
if (this._isdone) {
var results = func.apply(context, this.results);
doCallbackResults(results);
} else {
this._callbacks.push(function(){
var results = func.apply(context, arguments);
doCallbackResults(results);
});
}
return p;
};
Promise.prototype.done = function(){
this.results = arguments;
this._isdone = true;
for (var i=0; i<this._callbacks.length; i++) {
this._callbacks[i].apply(null, arguments);
}
this._callbacks = [];
};
Promise.join = function(promises){
var p = new Promise();
var results = [];
if (!promises || !promises.length) {
p.done(results);
return p;
}
var numdone = 0;
var total = promises.length;
function notifier(i) {
return function() {
numdone += 1;
results[i] = Array.prototype.slice.call(arguments);
if (numdone === total) {
p.done(results);
}
};
}
for (var i = 0; i < total; i++) {
promises[i].then(notifier(i));
}
return p;
};
Promise.chain = function(funcs, args) {
var p = new Promise();
if (!funcs || !funcs.length) {
p.done.apply(p, args);
} else {
funcs[0].apply(null, args).then(function(){
funcs.splice(0, 1);
Promise.chain(funcs, arguments).then(function(){
p.done.apply(p, arguments);
});
});
}
return p;
};
})();
另附测试代码如下：
/**
* script: test.js
* description: promise.js测试代码
* */
var promise = require('./mypromise');
function asyncfoo() {
var p = new promise.Promise();
setTimeout(function(){
p.done();
}, 1000);
return p;
}
function syncfoo() {
var p = new promise.Promise();
p.done();
return p;
}
var o = {};
/*
asyncfoo().then(function(){
return 'Raymond';
}, o).then(function(err, name){
o.name = name;
return asyncfoo().then(asyncfoo).then(function(){
return asyncfoo().then(asyncfoo).then(function(){
return 18;
});
});
}, o).then(function(err, age){
o.age = age;
return asyncfoo().then(asyncfoo).then(function(){
return asyncfoo().then(asyncfoo).then(function(){
return 'boy';
});
}).then(function(err, sex){
return sex;
});
}).then(function(err, sex){
o.sex = sex;
return 'Hello, world!';
}).then(function(err, say){
o.say = say;
console.dir(o);
});
syncfoo().then(function(){
return 'Raymond';
}, o).then(function(err, name){
o.name = name;
return syncfoo().then(syncfoo).then(function(){
return syncfoo().then(syncfoo).then(function(){
return 18;
});
});
}, o).then(function(err, age){
o.age = age;
return asyncfoo().then(asyncfoo).then(function(){
return asyncfoo().then(asyncfoo).then(function(){
return 'boy';
});
}).then(function(err, sex){
return sex;
});
}).then(function(err, sex){
o.sex = sex;
return 'Hello, world!';
}).then(function(err, say){
o.say = say;
console.dir(o);
});
*/
function asyncfoo1(){
var p = new promise.Promise();
setTimeout(function(){
p.done(null, 'Raymond');
}, 1000);
return p;
}
function asyncfoo2(err, name){
o.name = name;
var p = new promise.Promise();
setTimeout(function(){
p.done(null, 18);
}, 1000);
return p;
}
function asyncfoo3(err, age){
o.age = age;
var p = new promise.Promise();
setTimeout(function(){
p.done(null, 'boy');
}, 1000);
return p;
}
function asyncfoo4(){
var p = new promise.Promise();
setTimeout(function(){
p.done(null, 'Hello, world!');
}, 1000);
return p;
}
promise.Promise.chain([asyncfoo1, asyncfoo2, asyncfoo3]).then(function(err, sex){
o.sex = sex;
return asyncfoo4();
}).then(function(err, say){
o.say = say;
}).then(function(){
console.dir(o);
});
