[feat]最简版deferred

Author: 陈亮16

JS/simulate-deferred.js

@@ -0,0 +1,74 @@
+// https://github.com/mochi/mochikit/blob/master/MochiKit/Async.js
+// JavaScript 框架设计 chapter12
+Deferred = function(canceller){
+  this.state = -1;
+  this.fired = 0;
+  this.results = [null, null];
+  this.paused = 0;
+  this.chain = [];
+  this.canceller = canceller;
+  this.silentlyCancelled = false;
+}
+
+Deferred.prototype = {
+  state: function(){
+    return ['unfired', 'success', 'error'][this.state + 1];
+  },
+  _check: function(){
+
+  },
+  _errback: function(){
+
+  },
+  _resback: function(){
+    
+  },
+  callback: function(res){
+    this._check();
+    if(res instanceof Deferred){
+      throw new Error("不能调用 Deferred 作为 Deferred 参数");
+    }
+    this._resback(res);
+  },
+  addCallbacks: function(sucCall, errCall){
+    errCall = errCall || sucCall;
+    this.chain.push([sucCall, errCall]);
+    if(this.fired >= 0){
+      this._fire();
+    }
+    return this;
+  },
+  _fire: function(){
+    var chain = this.chain,
+      fired = this.fired,
+      res = this.results[fired],
+      self = this,
+      cb = null;
+    while(chain.length > 0 && this.paused === 0){
+      var pair = chain.shift();
+      var f = pair[fired];
+      if(f === null){
+        continue;
+      }
+      try{
+        res = f(res);
+        fired = res instanceof Error ? 1 : 0;
+        // if(res instanceof Deferred){
+        //   cb = function(res){
+
+        //   }
+        // }
+      }catch(err){
+        fired = 1;
+        res = err;
+      }
+    }
+    this.fired = fired;
+    this.results[fired] = res;
+    // if(cb && this.paused){
+
+    // }
+
+  }
+  
+}

JS/simulate-deferred.test.js

@@ -0,0 +1,12 @@
+'use strict'
+var deferred = require('./simulate-deferred');
+function increment(value){
+  console.log(value);
+  return value + 1;
+}
+
+var d = new Deferred();
+d.addCallbacks(increment)
+d.addCallbacks(increment)
+d.addCallbacks(increment)
+d.callback(1)