946 lines
29 KiB
JavaScript
946 lines
29 KiB
JavaScript
// Copyright 2007 Bob Ippolito. All Rights Reserved.
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// Modifications Copyright 2009 The Closure Library Authors. All Rights
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// Reserved.
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/**
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* @license Portions of this code are from MochiKit, received by
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* The Closure Authors under the MIT license. All other code is Copyright
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* 2005-2009 The Closure Authors. All Rights Reserved.
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*/
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/**
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* @fileoverview Classes for tracking asynchronous operations and handling the
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* results. The Deferred object here is patterned after the Deferred object in
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* the Twisted python networking framework.
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*
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* See: http://twistedmatrix.com/projects/core/documentation/howto/defer.html
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*
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* Based on the Dojo code which in turn is based on the MochiKit code.
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*
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* @author arv@google.com (Erik Arvidsson)
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* @author brenneman@google.com (Shawn Brenneman)
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*/
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goog.provide('goog.async.Deferred');
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goog.provide('goog.async.Deferred.AlreadyCalledError');
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goog.provide('goog.async.Deferred.CanceledError');
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goog.require('goog.Promise');
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goog.require('goog.Thenable');
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goog.require('goog.array');
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goog.require('goog.asserts');
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goog.require('goog.debug.Error');
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/**
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* A Deferred represents the result of an asynchronous operation. A Deferred
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* instance has no result when it is created, and is "fired" (given an initial
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* result) by calling {@code callback} or {@code errback}.
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*
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* Once fired, the result is passed through a sequence of callback functions
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* registered with {@code addCallback} or {@code addErrback}. The functions may
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* mutate the result before it is passed to the next function in the sequence.
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*
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* Callbacks and errbacks may be added at any time, including after the Deferred
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* has been "fired". If there are no pending actions in the execution sequence
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* of a fired Deferred, any new callback functions will be called with the last
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* computed result. Adding a callback function is the only way to access the
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* result of the Deferred.
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*
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* If a Deferred operation is canceled, an optional user-provided cancellation
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* function is invoked which may perform any special cleanup, followed by firing
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* the Deferred's errback sequence with a {@code CanceledError}. If the
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* Deferred has already fired, cancellation is ignored.
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*
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* Deferreds may be templated to a specific type they produce using generics
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* with syntax such as:
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*
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* /** @type {goog.async.Deferred<string>} *\
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* var d = new goog.async.Deferred();
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* // Compiler can infer that foo is a string.
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* d.addCallback(function(foo) {...});
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* d.callback('string'); // Checked to be passed a string
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*
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* Since deferreds are often used to produce different values across a chain,
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* the type information is not propagated across chains, but rather only
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* associated with specifically cast objects.
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*
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* @param {Function=} opt_onCancelFunction A function that will be called if the
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* Deferred is canceled. If provided, this function runs before the
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* Deferred is fired with a {@code CanceledError}.
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* @param {Object=} opt_defaultScope The default object context to call
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* callbacks and errbacks in.
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* @constructor
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* @implements {goog.Thenable<VALUE>}
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* @template VALUE
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*/
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goog.async.Deferred = function(opt_onCancelFunction, opt_defaultScope) {
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/**
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* Entries in the sequence are arrays containing a callback, an errback, and
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* an optional scope. The callback or errback in an entry may be null.
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* @type {!Array<!Array>}
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* @private
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*/
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this.sequence_ = [];
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/**
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* Optional function that will be called if the Deferred is canceled.
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* @type {Function|undefined}
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* @private
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*/
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this.onCancelFunction_ = opt_onCancelFunction;
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/**
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* The default scope to execute callbacks and errbacks in.
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* @type {Object}
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* @private
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*/
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this.defaultScope_ = opt_defaultScope || null;
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/**
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* Whether the Deferred has been fired.
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* @type {boolean}
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* @private
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*/
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this.fired_ = false;
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/**
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* Whether the last result in the execution sequence was an error.
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* @type {boolean}
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* @private
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*/
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this.hadError_ = false;
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/**
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* The current Deferred result, updated as callbacks and errbacks are
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* executed.
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* @type {*}
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* @private
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*/
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this.result_ = undefined;
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/**
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* Whether the Deferred is blocked waiting on another Deferred to fire. If a
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* callback or errback returns a Deferred as a result, the execution sequence
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* is blocked until that Deferred result becomes available.
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* @type {boolean}
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* @private
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*/
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this.blocked_ = false;
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/**
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* Whether this Deferred is blocking execution of another Deferred. If this
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* instance was returned as a result in another Deferred's execution
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* sequence,that other Deferred becomes blocked until this instance's
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* execution sequence completes. No additional callbacks may be added to a
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* Deferred once it is blocking another instance.
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* @type {boolean}
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* @private
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*/
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this.blocking_ = false;
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/**
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* Whether the Deferred has been canceled without having a custom cancel
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* function.
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* @type {boolean}
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* @private
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*/
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this.silentlyCanceled_ = false;
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/**
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* If an error is thrown during Deferred execution with no errback to catch
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* it, the error is rethrown after a timeout. Reporting the error after a
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* timeout allows execution to continue in the calling context (empty when
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* no error is scheduled).
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* @type {number}
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* @private
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*/
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this.unhandledErrorId_ = 0;
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/**
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* If this Deferred was created by branch(), this will be the "parent"
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* Deferred.
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* @type {goog.async.Deferred}
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* @private
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*/
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this.parent_ = null;
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/**
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* The number of Deferred objects that have been branched off this one. This
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* will be decremented whenever a branch is fired or canceled.
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* @type {number}
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* @private
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*/
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this.branches_ = 0;
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if (goog.async.Deferred.LONG_STACK_TRACES) {
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/**
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* Holds the stack trace at time of deferred creation if the JS engine
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* provides the Error.captureStackTrace API.
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* @private {?string}
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*/
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this.constructorStack_ = null;
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if (Error.captureStackTrace) {
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var target = { stack: '' };
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Error.captureStackTrace(target, goog.async.Deferred);
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// Check if Error.captureStackTrace worked. It fails in gjstest.
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if (typeof target.stack == 'string') {
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// Remove first line and force stringify to prevent memory leak due to
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// holding on to actual stack frames.
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this.constructorStack_ = target.stack.replace(/^[^\n]*\n/, '');
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}
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}
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}
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};
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/**
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* @define {boolean} Whether unhandled errors should always get rethrown to the
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* global scope. Defaults to the value of goog.DEBUG.
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*/
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goog.define('goog.async.Deferred.STRICT_ERRORS', false);
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/**
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* @define {boolean} Whether to attempt to make stack traces long. Defaults to
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* the value of goog.DEBUG.
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*/
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goog.define('goog.async.Deferred.LONG_STACK_TRACES', false);
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/**
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* Cancels a Deferred that has not yet been fired, or is blocked on another
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* deferred operation. If this Deferred is waiting for a blocking Deferred to
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* fire, the blocking Deferred will also be canceled.
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*
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* If this Deferred was created by calling branch() on a parent Deferred with
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* opt_propagateCancel set to true, the parent may also be canceled. If
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* opt_deepCancel is set, cancel() will be called on the parent (as well as any
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* other ancestors if the parent is also a branch). If one or more branches were
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* created with opt_propagateCancel set to true, the parent will be canceled if
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* cancel() is called on all of those branches.
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*
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* @param {boolean=} opt_deepCancel If true, cancels this Deferred's parent even
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* if cancel() hasn't been called on some of the parent's branches. Has no
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* effect on a branch without opt_propagateCancel set to true.
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*/
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goog.async.Deferred.prototype.cancel = function(opt_deepCancel) {
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if (!this.hasFired()) {
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if (this.parent_) {
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// Get rid of the parent reference before potentially running the parent's
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// canceler function to ensure that this cancellation isn't
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// double-counted.
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var parent = this.parent_;
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delete this.parent_;
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if (opt_deepCancel) {
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parent.cancel(opt_deepCancel);
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} else {
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parent.branchCancel_();
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}
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}
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if (this.onCancelFunction_) {
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// Call in user-specified scope.
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this.onCancelFunction_.call(this.defaultScope_, this);
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} else {
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this.silentlyCanceled_ = true;
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}
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if (!this.hasFired()) {
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this.errback(new goog.async.Deferred.CanceledError(this));
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}
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} else if (this.result_ instanceof goog.async.Deferred) {
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this.result_.cancel();
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}
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};
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/**
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* Handle a single branch being canceled. Once all branches are canceled, this
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* Deferred will be canceled as well.
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*
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* @private
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*/
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goog.async.Deferred.prototype.branchCancel_ = function() {
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this.branches_--;
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if (this.branches_ <= 0) {
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this.cancel();
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}
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};
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/**
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* Called after a blocking Deferred fires. Unblocks this Deferred and resumes
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* its execution sequence.
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*
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* @param {boolean} isSuccess Whether the result is a success or an error.
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* @param {*} res The result of the blocking Deferred.
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* @private
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*/
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goog.async.Deferred.prototype.continue_ = function(isSuccess, res) {
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this.blocked_ = false;
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this.updateResult_(isSuccess, res);
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};
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/**
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* Updates the current result based on the success or failure of the last action
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* in the execution sequence.
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*
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* @param {boolean} isSuccess Whether the new result is a success or an error.
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* @param {*} res The result.
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* @private
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*/
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goog.async.Deferred.prototype.updateResult_ = function(isSuccess, res) {
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this.fired_ = true;
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this.result_ = res;
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this.hadError_ = !isSuccess;
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this.fire_();
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};
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/**
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* Verifies that the Deferred has not yet been fired.
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*
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* @private
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* @throws {Error} If this has already been fired.
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*/
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goog.async.Deferred.prototype.check_ = function() {
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if (this.hasFired()) {
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if (!this.silentlyCanceled_) {
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throw new goog.async.Deferred.AlreadyCalledError(this);
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}
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this.silentlyCanceled_ = false;
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}
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};
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/**
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* Fire the execution sequence for this Deferred by passing the starting result
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* to the first registered callback.
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* @param {VALUE=} opt_result The starting result.
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*/
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goog.async.Deferred.prototype.callback = function(opt_result) {
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this.check_();
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this.assertNotDeferred_(opt_result);
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this.updateResult_(true /* isSuccess */, opt_result);
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};
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/**
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* Fire the execution sequence for this Deferred by passing the starting error
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* result to the first registered errback.
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* @param {*=} opt_result The starting error.
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*/
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goog.async.Deferred.prototype.errback = function(opt_result) {
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this.check_();
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this.assertNotDeferred_(opt_result);
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this.makeStackTraceLong_(opt_result);
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this.updateResult_(false /* isSuccess */, opt_result);
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};
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/**
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* Attempt to make the error's stack trace be long in that it contains the
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* stack trace from the point where the deferred was created on top of the
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* current stack trace to give additional context.
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* @param {*} error
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* @private
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*/
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goog.async.Deferred.prototype.makeStackTraceLong_ = function(error) {
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if (!goog.async.Deferred.LONG_STACK_TRACES) {
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return;
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}
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if (this.constructorStack_ && goog.isObject(error) && error.stack &&
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// Stack looks like it was system generated. See
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// https://code.google.com/p/v8/wiki/JavaScriptStackTraceApi
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(/^[^\n]+(\n [^\n]+)+/).test(error.stack)) {
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error.stack = error.stack + '\nDEFERRED OPERATION:\n' +
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this.constructorStack_;
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}
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};
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/**
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* Asserts that an object is not a Deferred.
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* @param {*} obj The object to test.
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* @throws {Error} Throws an exception if the object is a Deferred.
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* @private
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*/
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goog.async.Deferred.prototype.assertNotDeferred_ = function(obj) {
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goog.asserts.assert(
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!(obj instanceof goog.async.Deferred),
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'An execution sequence may not be initiated with a blocking Deferred.');
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};
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/**
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* Register a callback function to be called with a successful result. If no
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* value is returned by the callback function, the result value is unchanged. If
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* a new value is returned, it becomes the Deferred result and will be passed to
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* the next callback in the execution sequence.
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*
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* If the function throws an error, the error becomes the new result and will be
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* passed to the next errback in the execution chain.
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*
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* If the function returns a Deferred, the execution sequence will be blocked
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* until that Deferred fires. Its result will be passed to the next callback (or
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* errback if it is an error result) in this Deferred's execution sequence.
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*
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* @param {function(this:T,VALUE):?} cb The function to be called with a
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* successful result.
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* @param {T=} opt_scope An optional scope to call the callback in.
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* @return {!goog.async.Deferred} This Deferred.
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* @template T
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*/
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goog.async.Deferred.prototype.addCallback = function(cb, opt_scope) {
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return this.addCallbacks(cb, null, opt_scope);
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};
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/**
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* Register a callback function to be called with an error result. If no value
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* is returned by the function, the error result is unchanged. If a new error
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* value is returned or thrown, that error becomes the Deferred result and will
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* be passed to the next errback in the execution sequence.
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*
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* If the errback function handles the error by returning a non-error value,
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* that result will be passed to the next normal callback in the sequence.
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*
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* If the function returns a Deferred, the execution sequence will be blocked
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* until that Deferred fires. Its result will be passed to the next callback (or
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* errback if it is an error result) in this Deferred's execution sequence.
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*
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* @param {function(this:T,?):?} eb The function to be called on an
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* unsuccessful result.
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* @param {T=} opt_scope An optional scope to call the errback in.
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* @return {!goog.async.Deferred<VALUE>} This Deferred.
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* @template T
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*/
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goog.async.Deferred.prototype.addErrback = function(eb, opt_scope) {
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return this.addCallbacks(null, eb, opt_scope);
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};
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/**
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* Registers one function as both a callback and errback.
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*
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* @param {function(this:T,?):?} f The function to be called on any result.
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* @param {T=} opt_scope An optional scope to call the function in.
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* @return {!goog.async.Deferred} This Deferred.
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* @template T
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*/
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goog.async.Deferred.prototype.addBoth = function(f, opt_scope) {
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return this.addCallbacks(f, f, opt_scope);
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};
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/**
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* Like addBoth, but propagates uncaught exceptions in the errback.
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*
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* @param {function(this:T,?):?} f The function to be called on any result.
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* @param {T=} opt_scope An optional scope to call the function in.
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* @return {!goog.async.Deferred<VALUE>} This Deferred.
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* @template T
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*/
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goog.async.Deferred.prototype.addFinally = function(f, opt_scope) {
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return this.addCallbacks(f, function(err) {
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var result = f.call(/** @type {?} */ (this), err);
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if (!goog.isDef(result)) {
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throw err;
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}
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return result;
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}, opt_scope);
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};
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/**
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* Registers a callback function and an errback function at the same position
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* in the execution sequence. Only one of these functions will execute,
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* depending on the error state during the execution sequence.
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*
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* NOTE: This is not equivalent to {@code def.addCallback().addErrback()}! If
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* the callback is invoked, the errback will be skipped, and vice versa.
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*
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* @param {?(function(this:T,VALUE):?)} cb The function to be called on a
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* successful result.
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* @param {?(function(this:T,?):?)} eb The function to be called on an
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* unsuccessful result.
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* @param {T=} opt_scope An optional scope to call the functions in.
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* @return {!goog.async.Deferred} This Deferred.
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* @template T
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*/
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goog.async.Deferred.prototype.addCallbacks = function(cb, eb, opt_scope) {
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goog.asserts.assert(!this.blocking_, 'Blocking Deferreds can not be re-used');
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this.sequence_.push([cb, eb, opt_scope]);
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if (this.hasFired()) {
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this.fire_();
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}
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return this;
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};
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/**
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* Implements {@see goog.Thenable} for seamless integration with
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* {@see goog.Promise}.
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* Deferred results are mutable and may represent multiple values over
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* their lifetime. Calling {@code then} on a Deferred returns a Promise
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* with the result of the Deferred at that point in its callback chain.
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* Note that if the Deferred result is never mutated, and only
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* {@code then} calls are made, the Deferred will behave like a Promise.
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*
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* @override
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*/
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goog.async.Deferred.prototype.then = function(opt_onFulfilled, opt_onRejected,
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opt_context) {
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var resolve, reject;
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var promise = new goog.Promise(function(res, rej) {
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// Copying resolvers to outer scope, so that they are available when the
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// deferred callback fires (which may be synchronous).
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resolve = res;
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reject = rej;
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});
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this.addCallbacks(resolve, function(reason) {
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if (reason instanceof goog.async.Deferred.CanceledError) {
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promise.cancel();
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} else {
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reject(reason);
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}
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});
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return promise.then(opt_onFulfilled, opt_onRejected, opt_context);
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};
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|
goog.Thenable.addImplementation(goog.async.Deferred);
|
|
|
|
|
|
/**
|
|
* Links another Deferred to the end of this Deferred's execution sequence. The
|
|
* result of this execution sequence will be passed as the starting result for
|
|
* the chained Deferred, invoking either its first callback or errback.
|
|
*
|
|
* @param {!goog.async.Deferred} otherDeferred The Deferred to chain.
|
|
* @return {!goog.async.Deferred} This Deferred.
|
|
*/
|
|
goog.async.Deferred.prototype.chainDeferred = function(otherDeferred) {
|
|
this.addCallbacks(
|
|
otherDeferred.callback, otherDeferred.errback, otherDeferred);
|
|
return this;
|
|
};
|
|
|
|
|
|
/**
|
|
* Makes this Deferred wait for another Deferred's execution sequence to
|
|
* complete before continuing.
|
|
*
|
|
* This is equivalent to adding a callback that returns {@code otherDeferred},
|
|
* but doesn't prevent additional callbacks from being added to
|
|
* {@code otherDeferred}.
|
|
*
|
|
* @param {!goog.async.Deferred|!goog.Thenable} otherDeferred The Deferred
|
|
* to wait for.
|
|
* @return {!goog.async.Deferred} This Deferred.
|
|
*/
|
|
goog.async.Deferred.prototype.awaitDeferred = function(otherDeferred) {
|
|
if (!(otherDeferred instanceof goog.async.Deferred)) {
|
|
// The Thenable case.
|
|
return this.addCallback(function() {
|
|
return otherDeferred;
|
|
});
|
|
}
|
|
return this.addCallback(goog.bind(otherDeferred.branch, otherDeferred));
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a branch off this Deferred's execution sequence, and returns it as a
|
|
* new Deferred. The branched Deferred's starting result will be shared with the
|
|
* parent at the point of the branch, even if further callbacks are added to the
|
|
* parent.
|
|
*
|
|
* All branches at the same stage in the execution sequence will receive the
|
|
* same starting value.
|
|
*
|
|
* @param {boolean=} opt_propagateCancel If cancel() is called on every child
|
|
* branch created with opt_propagateCancel, the parent will be canceled as
|
|
* well.
|
|
* @return {!goog.async.Deferred<VALUE>} A Deferred that will be started with
|
|
* the computed result from this stage in the execution sequence.
|
|
*/
|
|
goog.async.Deferred.prototype.branch = function(opt_propagateCancel) {
|
|
var d = new goog.async.Deferred();
|
|
this.chainDeferred(d);
|
|
if (opt_propagateCancel) {
|
|
d.parent_ = this;
|
|
this.branches_++;
|
|
}
|
|
return d;
|
|
};
|
|
|
|
|
|
/**
|
|
* @return {boolean} Whether the execution sequence has been started on this
|
|
* Deferred by invoking {@code callback} or {@code errback}.
|
|
*/
|
|
goog.async.Deferred.prototype.hasFired = function() {
|
|
return this.fired_;
|
|
};
|
|
|
|
|
|
/**
|
|
* @param {*} res The latest result in the execution sequence.
|
|
* @return {boolean} Whether the current result is an error that should cause
|
|
* the next errback to fire. May be overridden by subclasses to handle
|
|
* special error types.
|
|
* @protected
|
|
*/
|
|
goog.async.Deferred.prototype.isError = function(res) {
|
|
return res instanceof Error;
|
|
};
|
|
|
|
|
|
/**
|
|
* @return {boolean} Whether an errback exists in the remaining sequence.
|
|
* @private
|
|
*/
|
|
goog.async.Deferred.prototype.hasErrback_ = function() {
|
|
return goog.array.some(this.sequence_, function(sequenceRow) {
|
|
// The errback is the second element in the array.
|
|
return goog.isFunction(sequenceRow[1]);
|
|
});
|
|
};
|
|
|
|
|
|
/**
|
|
* Exhausts the execution sequence while a result is available. The result may
|
|
* be modified by callbacks or errbacks, and execution will block if the
|
|
* returned result is an incomplete Deferred.
|
|
*
|
|
* @private
|
|
*/
|
|
goog.async.Deferred.prototype.fire_ = function() {
|
|
if (this.unhandledErrorId_ && this.hasFired() && this.hasErrback_()) {
|
|
// It is possible to add errbacks after the Deferred has fired. If a new
|
|
// errback is added immediately after the Deferred encountered an unhandled
|
|
// error, but before that error is rethrown, the error is unscheduled.
|
|
goog.async.Deferred.unscheduleError_(this.unhandledErrorId_);
|
|
this.unhandledErrorId_ = 0;
|
|
}
|
|
|
|
if (this.parent_) {
|
|
this.parent_.branches_--;
|
|
delete this.parent_;
|
|
}
|
|
|
|
var res = this.result_;
|
|
var unhandledException = false;
|
|
var isNewlyBlocked = false;
|
|
|
|
while (this.sequence_.length && !this.blocked_) {
|
|
var sequenceEntry = this.sequence_.shift();
|
|
|
|
var callback = sequenceEntry[0];
|
|
var errback = sequenceEntry[1];
|
|
var scope = sequenceEntry[2];
|
|
|
|
var f = this.hadError_ ? errback : callback;
|
|
if (f) {
|
|
|
|
try {
|
|
var ret = f.call(scope || this.defaultScope_, res);
|
|
|
|
// If no result, then use previous result.
|
|
if (goog.isDef(ret)) {
|
|
// Bubble up the error as long as the return value hasn't changed.
|
|
this.hadError_ = this.hadError_ && (ret == res || this.isError(ret));
|
|
this.result_ = res = ret;
|
|
}
|
|
|
|
if (goog.Thenable.isImplementedBy(res) ||
|
|
(typeof goog.global['Promise'] === 'function' &&
|
|
res instanceof goog.global['Promise'])) {
|
|
isNewlyBlocked = true;
|
|
this.blocked_ = true;
|
|
}
|
|
|
|
} catch (ex) {
|
|
res = ex;
|
|
this.hadError_ = true;
|
|
this.makeStackTraceLong_(res);
|
|
|
|
if (!this.hasErrback_()) {
|
|
// If an error is thrown with no additional errbacks in the queue,
|
|
// prepare to rethrow the error.
|
|
unhandledException = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
this.result_ = res;
|
|
|
|
if (isNewlyBlocked) {
|
|
var onCallback = goog.bind(this.continue_, this, true /* isSuccess */);
|
|
var onErrback = goog.bind(this.continue_, this, false /* isSuccess */);
|
|
|
|
if (res instanceof goog.async.Deferred) {
|
|
res.addCallbacks(onCallback, onErrback);
|
|
res.blocking_ = true;
|
|
} else {
|
|
res.then(onCallback, onErrback);
|
|
}
|
|
} else if (goog.async.Deferred.STRICT_ERRORS && this.isError(res) &&
|
|
!(res instanceof goog.async.Deferred.CanceledError)) {
|
|
this.hadError_ = true;
|
|
unhandledException = true;
|
|
}
|
|
|
|
if (unhandledException) {
|
|
// Rethrow the unhandled error after a timeout. Execution will continue, but
|
|
// the error will be seen by global handlers and the user. The throw will
|
|
// be canceled if another errback is appended before the timeout executes.
|
|
// The error's original stack trace is preserved where available.
|
|
this.unhandledErrorId_ = goog.async.Deferred.scheduleError_(res);
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a Deferred that has an initial result.
|
|
*
|
|
* @param {*=} opt_result The result.
|
|
* @return {!goog.async.Deferred} The new Deferred.
|
|
*/
|
|
goog.async.Deferred.succeed = function(opt_result) {
|
|
var d = new goog.async.Deferred();
|
|
d.callback(opt_result);
|
|
return d;
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a Deferred that fires when the given promise resolves.
|
|
* Use only during migration to Promises.
|
|
*
|
|
* @param {!goog.Promise<T>} promise
|
|
* @return {!goog.async.Deferred<T>} The new Deferred.
|
|
* @template T
|
|
*/
|
|
goog.async.Deferred.fromPromise = function(promise) {
|
|
var d = new goog.async.Deferred();
|
|
d.callback();
|
|
d.addCallback(function() {
|
|
return promise;
|
|
});
|
|
return d;
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a Deferred that has an initial error result.
|
|
*
|
|
* @param {*} res The error result.
|
|
* @return {!goog.async.Deferred} The new Deferred.
|
|
*/
|
|
goog.async.Deferred.fail = function(res) {
|
|
var d = new goog.async.Deferred();
|
|
d.errback(res);
|
|
return d;
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a Deferred that has already been canceled.
|
|
*
|
|
* @return {!goog.async.Deferred} The new Deferred.
|
|
*/
|
|
goog.async.Deferred.canceled = function() {
|
|
var d = new goog.async.Deferred();
|
|
d.cancel();
|
|
return d;
|
|
};
|
|
|
|
|
|
/**
|
|
* Normalizes values that may or may not be Deferreds.
|
|
*
|
|
* If the input value is a Deferred, the Deferred is branched (so the original
|
|
* execution sequence is not modified) and the input callback added to the new
|
|
* branch. The branch is returned to the caller.
|
|
*
|
|
* If the input value is not a Deferred, the callback will be executed
|
|
* immediately and an already firing Deferred will be returned to the caller.
|
|
*
|
|
* In the following (contrived) example, if <code>isImmediate</code> is true
|
|
* then 3 is alerted immediately, otherwise 6 is alerted after a 2-second delay.
|
|
*
|
|
* <pre>
|
|
* var value;
|
|
* if (isImmediate) {
|
|
* value = 3;
|
|
* } else {
|
|
* value = new goog.async.Deferred();
|
|
* setTimeout(function() { value.callback(6); }, 2000);
|
|
* }
|
|
*
|
|
* var d = goog.async.Deferred.when(value, alert);
|
|
* </pre>
|
|
*
|
|
* @param {*} value Deferred or normal value to pass to the callback.
|
|
* @param {function(this:T, ?):?} callback The callback to execute.
|
|
* @param {T=} opt_scope An optional scope to call the callback in.
|
|
* @return {!goog.async.Deferred} A new Deferred that will call the input
|
|
* callback with the input value.
|
|
* @template T
|
|
*/
|
|
goog.async.Deferred.when = function(value, callback, opt_scope) {
|
|
if (value instanceof goog.async.Deferred) {
|
|
return value.branch(true).addCallback(callback, opt_scope);
|
|
} else {
|
|
return goog.async.Deferred.succeed(value).addCallback(callback, opt_scope);
|
|
}
|
|
};
|
|
|
|
|
|
|
|
/**
|
|
* An error sub class that is used when a Deferred has already been called.
|
|
* @param {!goog.async.Deferred} deferred The Deferred.
|
|
*
|
|
* @constructor
|
|
* @extends {goog.debug.Error}
|
|
*/
|
|
goog.async.Deferred.AlreadyCalledError = function(deferred) {
|
|
goog.debug.Error.call(this);
|
|
|
|
/**
|
|
* The Deferred that raised this error.
|
|
* @type {goog.async.Deferred}
|
|
*/
|
|
this.deferred = deferred;
|
|
};
|
|
goog.inherits(goog.async.Deferred.AlreadyCalledError, goog.debug.Error);
|
|
|
|
|
|
/** @override */
|
|
goog.async.Deferred.AlreadyCalledError.prototype.message =
|
|
'Deferred has already fired';
|
|
|
|
|
|
/** @override */
|
|
goog.async.Deferred.AlreadyCalledError.prototype.name = 'AlreadyCalledError';
|
|
|
|
|
|
|
|
/**
|
|
* An error sub class that is used when a Deferred is canceled.
|
|
*
|
|
* @param {!goog.async.Deferred} deferred The Deferred object.
|
|
* @constructor
|
|
* @extends {goog.debug.Error}
|
|
*/
|
|
goog.async.Deferred.CanceledError = function(deferred) {
|
|
goog.debug.Error.call(this);
|
|
|
|
/**
|
|
* The Deferred that raised this error.
|
|
* @type {goog.async.Deferred}
|
|
*/
|
|
this.deferred = deferred;
|
|
};
|
|
goog.inherits(goog.async.Deferred.CanceledError, goog.debug.Error);
|
|
|
|
|
|
/** @override */
|
|
goog.async.Deferred.CanceledError.prototype.message = 'Deferred was canceled';
|
|
|
|
|
|
/** @override */
|
|
goog.async.Deferred.CanceledError.prototype.name = 'CanceledError';
|
|
|
|
|
|
|
|
/**
|
|
* Wrapper around errors that are scheduled to be thrown by failing deferreds
|
|
* after a timeout.
|
|
*
|
|
* @param {*} error Error from a failing deferred.
|
|
* @constructor
|
|
* @final
|
|
* @private
|
|
* @struct
|
|
*/
|
|
goog.async.Deferred.Error_ = function(error) {
|
|
/** @const @private {number} */
|
|
this.id_ = goog.global.setTimeout(goog.bind(this.throwError, this), 0);
|
|
|
|
/** @const @private {*} */
|
|
this.error_ = error;
|
|
};
|
|
|
|
|
|
/**
|
|
* Actually throws the error and removes it from the list of pending
|
|
* deferred errors.
|
|
*/
|
|
goog.async.Deferred.Error_.prototype.throwError = function() {
|
|
goog.asserts.assert(goog.async.Deferred.errorMap_[this.id_],
|
|
'Cannot throw an error that is not scheduled.');
|
|
delete goog.async.Deferred.errorMap_[this.id_];
|
|
throw this.error_;
|
|
};
|
|
|
|
|
|
/**
|
|
* Resets the error throw timer.
|
|
*/
|
|
goog.async.Deferred.Error_.prototype.resetTimer = function() {
|
|
goog.global.clearTimeout(this.id_);
|
|
};
|
|
|
|
|
|
/**
|
|
* Map of unhandled errors scheduled to be rethrown in a future timestep.
|
|
* @private {!Object<(number|string), goog.async.Deferred.Error_>}
|
|
*/
|
|
goog.async.Deferred.errorMap_ = {};
|
|
|
|
|
|
/**
|
|
* Schedules an error to be thrown after a delay.
|
|
* @param {*} error Error from a failing deferred.
|
|
* @return {number} Id of the error.
|
|
* @private
|
|
*/
|
|
goog.async.Deferred.scheduleError_ = function(error) {
|
|
var deferredError = new goog.async.Deferred.Error_(error);
|
|
goog.async.Deferred.errorMap_[deferredError.id_] = deferredError;
|
|
return deferredError.id_;
|
|
};
|
|
|
|
|
|
/**
|
|
* Unschedules an error from being thrown.
|
|
* @param {number} id Id of the deferred error to unschedule.
|
|
* @private
|
|
*/
|
|
goog.async.Deferred.unscheduleError_ = function(id) {
|
|
var error = goog.async.Deferred.errorMap_[id];
|
|
if (error) {
|
|
error.resetTimer();
|
|
delete goog.async.Deferred.errorMap_[id];
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Asserts that there are no pending deferred errors. If there are any
|
|
* scheduled errors, one will be thrown immediately to make this function fail.
|
|
*/
|
|
goog.async.Deferred.assertNoErrors = function() {
|
|
var map = goog.async.Deferred.errorMap_;
|
|
for (var key in map) {
|
|
var error = map[key];
|
|
error.resetTimer();
|
|
error.throwError();
|
|
}
|
|
};
|