Issue 3515 - Added polyfill for ES6 promises

lib/polyfills/promise.js

+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2015 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+(function(global)
+{
+  if ("Promise" in global)
+    return;
+
+  var PENDING = 0;
+  var FULFILLED = 1;
+  var REJECTED = 2;
+
+  var Promise = global.Promise = function(executor)
+  {
+    this._state = PENDING;
+    this._value = undefined;
+    this._subscriptions = [];
+
+    try
+    {
+      executor(this._emit.bind(this, FULFILLED),
+               this._emit.bind(this, REJECTED));
+    }
+    catch (reason)
+    {
+      this._emit(REJECTED, reason);
+    }
+  };
+
+  Promise.prototype = {
+    _dispatch: function(onFulfilled, onRejected, resolve, reject)
+    {
+      var callback = this._state == FULFILLED ? onFulfilled : onRejected;
+
+      if (typeof callback == "function")
+      {
+        var result;
+
+        try
+        {
+          result = callback(this._value);
+        }
+        catch (reason)
+        {
+          reject(reason);
+          return;
+        }
+
+        Promise.resolve(result).then(resolve, reject);
+      }
+      else if (this._state == FULFILLED)
+      {
+        resolve(this._value);
+      }
+      else if (this._state == REJECTED)
+      {
+        reject(this._value);
+      }
+    },
+    _dispatchSubscriptions: function()
+    {
+      if (this._state == REJECTED && this._subscriptions.length == 0)
+        console.error('Uncaught (in promise)', this._value);
+
+      for (var i = 0; i < this._subscriptions.length; i++)
+        this._dispatch.apply(this, this._subscriptions[i]);
+
+      this._subscriptions = null;
+    },
+    _emit: function(state, value)
+    {
+      if (this._state != PENDING)
+        return;
+
+      this._state = state;
+      this._value = value;
+
+      setTimeout(this._dispatchSubscriptions.bind(this), 0);
+    },
+    then: function(onFulfilled, onRejected)
+    {
+      return new Promise(function(resolve, reject)
+      {
+        if (this._subscriptions)
+          this._subscriptions.push([onFulfilled, onRejected, resolve, reject]);
+        else
+          setTimeout(
+            this._dispatch.bind(this), 0,
+            onFulfilled, onRejected, resolve, reject
+          );
+      }.bind(this));
+    },
+    catch: function(onRejected)
+    {
+      return this.then(undefined, onRejected);
+    }
+  };
+
+  Promise.resolve = function(value)
+  {
+    if (value instanceof Promise)
+      return value;
+    return new Promise(function(resolve, reject) { resolve(value); });
+  };
+
+  Promise.reject = function(reason)
+  {
+    return new Promise(function(resolve, reject) { reject(reason); });
+  };
+
+  Promise.all = function(promises)
+  {
+    return new Promise(function(resolve, reject)
+    {
+      var count = promises.length;
+      var result = new Array(count);
+
+      if (count == 0)
+      {
+        resolve(result);
+        return;
+      }
+
+      promises.forEach(function(promise, i)
+      {
+        Promise.resolve(promise).then(
+          function(value)
+          {
+            result[i] = value;
+            if (--count == 0)
+              resolve(result);
+          },
+          reject
+        );
+      });
+    });
+  };
+})(this);