refactor($q): separate Promise from Deferred

Closes angular#15064

BREAKING CHANGE:

Previously, the `Deferred` object returned by `$q.defer()` delegated the
`resolve()`, `reject()` and `notify()` methods to `Deferred.prototype`. Thus, it
was possible to modify `Deferred.prototype` and have the changes reflect to all
`Deferred` objects.

This commit removes that delegation, so modifying the above three methods on
`Deferred.prototype` will no longer have an effect on `Deferred` objects.

Author: jbedard

src/ng/q.js

@@ -299,14 +299,18 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
    * @returns {Deferred} Returns a new instance of deferred.
    */
   function defer() {
-    var d = new Deferred();
-    //Necessary to support unbound execution :/
-    d.resolve = simpleBind(d, d.resolve);
-    d.reject = simpleBind(d, d.reject);
-    d.notify = simpleBind(d, d.notify);
-    return d;
+    return new Deferred();
   }
 
+  function Deferred() {
+    var promise = this.promise = new Promise();
+    //Non prototype methods necessary to support unbound execution :/
+    this.resolve = function(val) { resolvePromise(promise, val); };
+    this.reject = function(reason) { rejectPromise(promise, reason); };
+    this.notify = function(progress) { notifyPromise(promise, progress); };
+  }
+
+
   function Promise() {
     this.$$state = { status: 0 };
   }
@@ -316,13 +320,13 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
       if (isUndefined(onFulfilled) && isUndefined(onRejected) && isUndefined(progressBack)) {
         return this;
       }
-      var result = new Deferred();
+      var result = new Promise();
 
       this.$$state.pending = this.$$state.pending || [];
       this.$$state.pending.push([result, onFulfilled, onRejected, progressBack]);
       if (this.$$state.status > 0) scheduleProcessQueue(this.$$state);
 
-      return result.promise;
+      return result;
     },
 
     'catch': function(callback) {
@@ -338,34 +342,27 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
     }
   });
 
-  //Faster, more basic than angular.bind http://jsperf.com/angular-bind-vs-custom-vs-native
-  function simpleBind(context, fn) {
-    return function(value) {
-      fn.call(context, value);
-    };
-  }
-
   function processQueue(state) {
-    var fn, deferred, pending;
+    var fn, promise, pending;
 
     pending = state.pending;
     state.processScheduled = false;
     state.pending = undefined;
     try {
       for (var i = 0, ii = pending.length; i < ii; ++i) {
         state.pur = true;
-        deferred = pending[i][0];
+        promise = pending[i][0];
         fn = pending[i][state.status];
         try {
           if (isFunction(fn)) {
-            deferred.resolve(fn(state.value));
+            resolvePromise(promise, fn(state.value));
           } else if (state.status === 1) {
-            deferred.resolve(state.value);
+            resolvePromise(promise, state.value);
           } else {
-            deferred.reject(state.value);
+            rejectPromise(promise, state.value);
           }
         } catch (e) {
-          deferred.reject(e);
+          rejectPromise(promise, e);
         }
       }
     } finally {
@@ -401,83 +398,80 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
     nextTick(function() { processQueue(state); });
   }
 
-  function Deferred() {
-    this.promise = new Promise();
+  function resolvePromise(promise, val) {
+    if (promise.$$state.status) return;
+    if (val === promise) {
+      $$reject(promise, $qMinErr(
+        'qcycle',
+        'Expected promise to be resolved with value other than itself \'{0}\'',
+        val));
+    } else {
+      $$resolve(promise, val);
+    }
+
   }
 
-  extend(Deferred.prototype, {
-    resolve: function(val) {
-      if (this.promise.$$state.status) return;
-      if (val === this.promise) {
-        this.$$reject($qMinErr(
-          'qcycle',
-          'Expected promise to be resolved with value other than itself \'{0}\'',
-          val));
+  function $$resolve(promise, val) {
+    var then;
+    var done = false;
+    try {
+      if (isObject(val) || isFunction(val)) then = val.then;
+      if (isFunction(then)) {
+        promise.$$state.status = -1;
+        then.call(val, doResolve, doReject, doNotify);
       } else {
-        this.$$resolve(val);
-      }
-    },
-
-    $$resolve: function(val) {
-      var then;
-      var that = this;
-      var done = false;
-      try {
-        if (isObject(val) || isFunction(val)) then = val.then;
-        if (isFunction(then)) {
-          this.promise.$$state.status = -1;
-          then.call(val, resolvePromise, rejectPromise, simpleBind(this, this.notify));
-        } else {
-          this.promise.$$state.value = val;
-          this.promise.$$state.status = 1;
-          scheduleProcessQueue(this.promise.$$state);
-        }
-      } catch (e) {
-        rejectPromise(e);
+        promise.$$state.value = val;
+        promise.$$state.status = 1;
+        scheduleProcessQueue(promise.$$state);
       }
+    } catch (e) {
+      doReject(e);
+    }
 
-      function resolvePromise(val) {
-        if (done) return;
-        done = true;
-        that.$$resolve(val);
-      }
-      function rejectPromise(val) {
-        if (done) return;
-        done = true;
-        that.$$reject(val);
-      }
-    },
+    function doResolve(val) {
+      if (done) return;
+      done = true;
+      $$resolve(promise, val);
+    }
+    function doReject(val) {
+      if (done) return;
+      done = true;
+      $$reject(promise, val);
+    }
+    function doNotify(progress) {
+      notifyPromise(promise, progress);
+    }
+  }
 
-    reject: function(reason) {
-      if (this.promise.$$state.status) return;
-      this.$$reject(reason);
-    },
+  function rejectPromise(promise, reason) {
+    if (promise.$$state.status) return;
+    $$reject(promise, reason);
+  }
 
-    $$reject: function(reason) {
-      this.promise.$$state.value = reason;
-      this.promise.$$state.status = 2;
-      scheduleProcessQueue(this.promise.$$state);
-    },
+  function $$reject(promise, reason) {
+    promise.$$state.value = reason;
+    promise.$$state.status = 2;
+    scheduleProcessQueue(promise.$$state);
+  }
 
-    notify: function(progress) {
-      var callbacks = this.promise.$$state.pending;
-
-      if ((this.promise.$$state.status <= 0) && callbacks && callbacks.length) {
-        nextTick(function() {
-          var callback, result;
-          for (var i = 0, ii = callbacks.length; i < ii; i++) {
-            result = callbacks[i][0];
-            callback = callbacks[i][3];
-            try {
-              result.notify(isFunction(callback) ? callback(progress) : progress);
-            } catch (e) {
-              exceptionHandler(e);
-            }
+  function notifyPromise(promise, progress) {
+    var callbacks = promise.$$state.pending;
+
+    if ((promise.$$state.status <= 0) && callbacks && callbacks.length) {
+      nextTick(function() {
+        var callback, result;
+        for (var i = 0, ii = callbacks.length; i < ii; i++) {
+          result = callbacks[i][0];
+          callback = callbacks[i][3];
+          try {
+            notifyPromise(result, isFunction(callback) ? callback(progress) : progress);
+          } catch (e) {
+            exceptionHandler(e);
           }
-        });
-      }
+        }
+      });
     }
-  });
+  }
 
   /**
    * @ngdoc method
@@ -516,9 +510,9 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
    * @returns {Promise} Returns a promise that was already resolved as rejected with the `reason`.
    */
   function reject(reason) {
-    var result = new Deferred();
-    result.reject(reason);
-    return result.promise;
+    var result = new Promise();
+    rejectPromise(result, reason);
+    return result;
   }
 
   function handleCallback(value, resolver, callback) {
@@ -556,9 +550,9 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
 
 
   function when(value, callback, errback, progressBack) {
-    var result = new Deferred();
-    result.resolve(value);
-    return result.promise.then(callback, errback, progressBack);
+    var result = new Promise();
+    resolvePromise(result, value);
+    return result.then(callback, errback, progressBack);
   }
 
   /**
@@ -594,25 +588,25 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
    */
 
   function all(promises) {
-    var deferred = new Deferred(),
+    var result = new Promise(),
         counter = 0,
         results = isArray(promises) ? [] : {};
 
     forEach(promises, function(promise, key) {
       counter++;
       when(promise).then(function(value) {
         results[key] = value;
-        if (!(--counter)) deferred.resolve(results);
+        if (!(--counter)) resolvePromise(result, results);
       }, function(reason) {
-        deferred.reject(reason);
+        rejectPromise(result, reason);
       });
     });
 
     if (counter === 0) {
-      deferred.resolve(results);
+      resolvePromise(result, results);
     }
 
-    return deferred.promise;
+    return result;
   }
 
   /**
@@ -644,19 +638,19 @@ function qFactory(nextTick, exceptionHandler, errorOnUnhandledRejections) {
       throw $qMinErr('norslvr', 'Expected resolverFn, got \'{0}\'', resolver);
     }
 
-    var deferred = new Deferred();
+    var promise = new Promise();
 
     function resolveFn(value) {
-      deferred.resolve(value);
+      resolvePromise(promise, value);
     }
 
     function rejectFn(reason) {
-      deferred.reject(reason);
+      rejectPromise(promise, reason);
     }
 
     resolver(resolveFn, rejectFn);
 
-    return deferred.promise;
+    return promise;
   }
 
   // Let's make the instanceof operator work for promises, so that