| // Copyright 2008 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Defines a class useful for handling functions that must be |
| * invoked later when some condition holds. Examples include deferred function |
| * calls that return a boolean flag whether it succedeed or not. |
| * |
| * Example: |
| * |
| * function deferred() { |
| * var succeeded = false; |
| * // ... custom code |
| * return succeeded; |
| * } |
| * |
| * var deferredCall = new goog.async.ConditionalDelay(deferred); |
| * deferredCall.onSuccess = function() { |
| * alert('Success: The deferred function has been successfully executed.'); |
| * } |
| * deferredCall.onFailure = function() { |
| * alert('Failure: Time limit exceeded.'); |
| * } |
| * |
| * // Call the deferred() every 100 msec until it returns true, |
| * // or 5 seconds pass. |
| * deferredCall.start(100, 5000); |
| * |
| * // Stop the deferred function call (does nothing if it's not active). |
| * deferredCall.stop(); |
| * |
| */ |
| |
| |
| goog.provide('goog.async.ConditionalDelay'); |
| |
| goog.require('goog.Disposable'); |
| goog.require('goog.async.Delay'); |
| |
| |
| |
| /** |
| * A ConditionalDelay object invokes the associated function after a specified |
| * interval delay and checks its return value. If the function returns |
| * {@code true} the conditional delay is cancelled and {@see #onSuccess} |
| * is called. Otherwise this object keeps to invoke the deferred function until |
| * either it returns {@code true} or the timeout is exceeded. In the latter case |
| * the {@see #onFailure} method will be called. |
| * |
| * The interval duration and timeout can be specified each time the delay is |
| * started. Calling start on an active delay will reset the timer. |
| * |
| * @param {function():boolean} listener Function to call when the delay |
| * completes. Should return a value that type-converts to {@code true} if |
| * the call succeeded and this delay should be stopped. |
| * @param {Object=} opt_handler The object scope to invoke the function in. |
| * @constructor |
| * @extends {goog.Disposable} |
| */ |
| goog.async.ConditionalDelay = function(listener, opt_handler) { |
| goog.Disposable.call(this); |
| |
| /** |
| * The function that will be invoked after a delay. |
| * @type {function():boolean} |
| * @private |
| */ |
| this.listener_ = listener; |
| |
| /** |
| * The object context to invoke the callback in. |
| * @type {Object|undefined} |
| * @private |
| */ |
| this.handler_ = opt_handler; |
| |
| /** |
| * The underlying goog.async.Delay delegate object. |
| * @type {goog.async.Delay} |
| * @private |
| */ |
| this.delay_ = new goog.async.Delay( |
| goog.bind(this.onTick_, this), 0 /*interval*/, this /*scope*/); |
| }; |
| goog.inherits(goog.async.ConditionalDelay, goog.Disposable); |
| |
| |
| /** |
| * The delay interval in milliseconds to between the calls to the callback. |
| * Note, that the callback may be invoked earlier than this interval if the |
| * timeout is exceeded. |
| * @type {number} |
| * @private |
| */ |
| goog.async.ConditionalDelay.prototype.interval_ = 0; |
| |
| |
| /** |
| * The timeout timestamp until which the delay is to be executed. |
| * A negative value means no timeout. |
| * @type {number} |
| * @private |
| */ |
| goog.async.ConditionalDelay.prototype.runUntil_ = 0; |
| |
| |
| /** |
| * True if the listener has been executed, and it returned {@code true}. |
| * @type {boolean} |
| * @private |
| */ |
| goog.async.ConditionalDelay.prototype.isDone_ = false; |
| |
| |
| /** @override */ |
| goog.async.ConditionalDelay.prototype.disposeInternal = function() { |
| this.delay_.dispose(); |
| delete this.listener_; |
| delete this.handler_; |
| goog.async.ConditionalDelay.superClass_.disposeInternal.call(this); |
| }; |
| |
| |
| /** |
| * Starts the delay timer. The provided listener function will be called |
| * repeatedly after the specified interval until the function returns |
| * {@code true} or the timeout is exceeded. Calling start on an active timer |
| * will stop the timer first. |
| * @param {number=} opt_interval The time interval between the function |
| * invocations (in milliseconds). Default is 0. |
| * @param {number=} opt_timeout The timeout interval (in milliseconds). Takes |
| * precedence over the {@code opt_interval}, i.e. if the timeout is less |
| * than the invocation interval, the function will be called when the |
| * timeout is exceeded. A negative value means no timeout. Default is 0. |
| */ |
| goog.async.ConditionalDelay.prototype.start = function(opt_interval, |
| opt_timeout) { |
| this.stop(); |
| this.isDone_ = false; |
| |
| var timeout = opt_timeout || 0; |
| this.interval_ = Math.max(opt_interval || 0, 0); |
| this.runUntil_ = timeout < 0 ? -1 : (goog.now() + timeout); |
| this.delay_.start( |
| timeout < 0 ? this.interval_ : Math.min(this.interval_, timeout)); |
| }; |
| |
| |
| /** |
| * Stops the delay timer if it is active. No action is taken if the timer is not |
| * in use. |
| */ |
| goog.async.ConditionalDelay.prototype.stop = function() { |
| this.delay_.stop(); |
| }; |
| |
| |
| /** |
| * @return {boolean} True if the delay is currently active, false otherwise. |
| */ |
| goog.async.ConditionalDelay.prototype.isActive = function() { |
| return this.delay_.isActive(); |
| }; |
| |
| |
| /** |
| * @return {boolean} True if the listener has been executed and returned |
| * {@code true} since the last call to {@see #start}. |
| */ |
| goog.async.ConditionalDelay.prototype.isDone = function() { |
| return this.isDone_; |
| }; |
| |
| |
| /** |
| * Called when the listener has been successfully executed and returned |
| * {@code true}. The {@see #isDone} method should return {@code true} by now. |
| * Designed for inheritance, should be overridden by subclasses or on the |
| * instances if they care. |
| */ |
| goog.async.ConditionalDelay.prototype.onSuccess = function() { |
| // Do nothing by default. |
| }; |
| |
| |
| /** |
| * Called when this delayed call is cancelled because the timeout has been |
| * exceeded, and the listener has never returned {@code true}. |
| * Designed for inheritance, should be overridden by subclasses or on the |
| * instances if they care. |
| */ |
| goog.async.ConditionalDelay.prototype.onFailure = function() { |
| // Do nothing by default. |
| }; |
| |
| |
| /** |
| * A callback function for the underlying {@code goog.async.Delay} object. When |
| * executed the listener function is called, and if it returns {@code true} |
| * the delay is stopped and the {@see #onSuccess} method is invoked. |
| * If the timeout is exceeded the delay is stopped and the |
| * {@see #onFailure} method is called. |
| * @private |
| */ |
| goog.async.ConditionalDelay.prototype.onTick_ = function() { |
| var successful = this.listener_.call(this.handler_); |
| if (successful) { |
| this.isDone_ = true; |
| this.onSuccess(); |
| } else { |
| // Try to reschedule the task. |
| if (this.runUntil_ < 0) { |
| // No timeout. |
| this.delay_.start(this.interval_); |
| } else { |
| var timeLeft = this.runUntil_ - goog.now(); |
| if (timeLeft <= 0) { |
| this.onFailure(); |
| } else { |
| this.delay_.start(Math.min(this.interval_, timeLeft)); |
| } |
| } |
| } |
| }; |