[ABANDONED] Implement Promises.

Source/core/dom/Promise.js

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+(function(postTask) {
+    function append(fulfillCallback, rejectCallback)
+    {
+        if (this.associated.state === 'fulfilled') {
+            postTask(fulfillCallback.bind(undefined, this.associated.result));

[abarth-chromium, 2013/06/14 05:07:08]

We need to be careful about calling things like "bind" that can be modified by
the page.

+        } else if (this.associated.state === 'rejected') {
+            postTask(rejectCallback.bind(undefined, this.associated.result));
+        } else {
+            this.associated.fulfillCallbacks.push(fulfillCallback);
+            this.associated.rejectCallbacks.push(rejectCallback);
+        }
+    }
+
+    /**
+     * Promise.prototype.then API.
+     * @parameter {Function} fulfillCallback
+     * @parameter {Function} rejectCallback
+     */
+    function then(fulfillCallback, rejectCallback)
+    {
+        var resolver;
+        var promise = new Promise(function(r) { resolver = r; });
+        function fulfillWrapper(value)
+        {
+            if (fulfillCallback) {
+                try {
+                    value = fulfillCallback.call(promise, value);
+                } catch (e) {
+                    resolver.reject(e, true);
+                    return;
+                }
+            }
+            resolver.resolve(value, true);
+        }
+
+        function rejectWrapper(value)
+        {
+            if (rejectCallback) {
+                try {
+                    value = rejectCallback.call(promise, value);
+                } catch (e) {
+                    resolver.reject(e, true);
+                    return;
+                }
+                resolver.resolve(value, true);
+            }
+            resolver.reject(value, true);
+        }
+
+        this.append(fulfillWrapper, rejectWrapper);
+        return promise;
+    }
+
+    /**
+     * Promise.prototype.catch API.
+     * @parameter {Function} rejectCallback
+     */
+    function catch_(rejectCallback)
+    {
+        return this.then(undefined, rejectCallback);
+    }
+
+    // static methods
+
+    /**
+     * Promise.fulfill API.
+     * @parameter {?} value the value to be set as the promise result.
+     */
+    function fulfill(value)
+    {
+        var resolver;
+        var promise = new Promise(function(r) { resolver = r; });
+        resolver.fulfill(value);
+        return promise;
+    }
+
+    /**
+     * Promise.resolve API.
+     * @parameter {?} value the value to be set as the promise result.
+     */
+    function resolve(value)
+    {
+        var resolver;
+        var promise = new Promise(function(r) { resolver = r; });
+        resolver.resolve(value);
+        return promise;
+    }
+
+    /**
+     * Promise.reject API.
+     * @parameter {?} value the value to be set as the promise result.
+     */
+    function reject(value)
+    {
+        var resolver;
+        var promise = new Promise(function(r) { resolver = r; });
+        resolver.reject(value);
+        return promise;
+    }
+
+    /**
+     * Promise.every API.
+     * @parameters {...Promise} promises
+     */
+    function every()
+    {
+        var promises = Array.prototype.slice.call(arguments, 0);

[abarth-chromium, 2013/06/14 05:07:08]

Similarly, we don't want to depend on any statics.

+        var resolver;
+        var countdown = promises.length;
+        var results = [];
+        var resultPromise = new Promise(function(r) { resolver = r; });
+
+        if (promises.length === 0) {
+            resolver.resolve(undefined);
+            return resultPromise;
+        }
+        promises.forEach(function(promise, index) {
+            if (!(promise instanceof Promise)) {
+                throw TypeError();
+            }
+            // We use Promise.prototype.then instead of |append| function.
+            promise.then(function(result) {
+                results[index] = result;
+                if (--countdown === 0) {
+                    resolver.resolve(results, true);
+                }
+            }, function(result) {
+                resolver.reject(result, true);
+            });
+        });
+        return resultPromise;
+    }
+
+    /**
+     * Promise.any API.
+     * @parameters {...Promise} promises
+     */
+    function any()
+    {
+        var promises = Array.prototype.slice.call(arguments, 0);
+        var resolver;
+        var results = [];
+        var resultPromise = new Promise(function(r) { resolver = r; });
+
+        if (promises.length === 0) {
+            resolver.resolve(undefined);
+            return resultPromise;
+        }
+        promises.forEach(function(promise) {
+            if (!(promise instanceof Promise)) {
+                throw TypeError();
+            }
+            // We use Promise.prototype.then instead of |append| function.
+            promise.then(function(result) {
+                resolver.resolve(result, true);
+            }, function(result) {
+                resolver.reject(result, true);
+            });
+        });
+        return resultPromise;
+    }
+
+    /**
+     * Promise.some API.
+     * @parameters {...Promise} promises
+     */
+    function some()
+    {
+        var promises = Array.prototype.slice.call(arguments, 0);
+        var resolver;
+        var countdown = promises.length;
+        var results = [];
+        var resultPromise = new Promise(function(r) { resolver = r; });
+
+        if (promises.length === 0) {
+            resolver.resolve(undefined);
+            return resultPromise;
+        }
+        promises.forEach(function(promise, index) {
+            if (!(promise instanceof Promise)) {
+                throw TypeError();
+            }
+            // We use Promise.prototype.then instead of |append| function.
+            promise.then(function (result) {
+                resolver.resolve(result, true);
+            }, function(result) {
+                results[index] = result;
+                if (--countdown === 0) {
+                    resolver.reject(results, true);
+                }
+            });
+        });
+        return resultPromise;
+    }
+
+    /**
+     * Promise constructor.
+     * Note that this differs from Promise API.
+     * Blink bridge fills the gap.
+     */
+    function $Promise(callback)
+    {
+        this.associated = {
+            state: 'pending',
+            result: undefined,
+            fulfillCallbacks: [],
+            rejectCallbacks: []
+        };
+    }
+
+    $Promise.prototype = {
+        append: append,
+        then: then,
+        'catch': catch_
+    };
+    $Promise.fulfill = fulfill;
+    $Promise.resolve = resolve;
+    $Promise.reject = reject;
+    $Promise.every = every;
+    $Promise.any = any;
+    $Promise.some = some;
+    return Object.freeze($Promise);

[abarth-chromium, 2013/06/14 05:07:08]

Why Object.freeze?

+});