395 lines
13 KiB
JavaScript
395 lines
13 KiB
JavaScript
// Copyright 2005 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview A disposable implementation of a custom
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* listenable/event target. See also: documentation for
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* {@code goog.events.Listenable}.
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*
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* @author arv@google.com (Erik Arvidsson) [Original implementation]
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* @see ../demos/eventtarget.html
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* @see goog.events.Listenable
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*/
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goog.provide('goog.events.EventTarget');
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goog.require('goog.Disposable');
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goog.require('goog.asserts');
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goog.require('goog.events');
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goog.require('goog.events.Event');
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goog.require('goog.events.Listenable');
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goog.require('goog.events.ListenerMap');
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goog.require('goog.object');
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/**
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* An implementation of {@code goog.events.Listenable} with full W3C
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* EventTarget-like support (capture/bubble mechanism, stopping event
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* propagation, preventing default actions).
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*
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* You may subclass this class to turn your class into a Listenable.
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*
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* Unless propagation is stopped, an event dispatched by an
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* EventTarget will bubble to the parent returned by
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* {@code getParentEventTarget}. To set the parent, call
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* {@code setParentEventTarget}. Subclasses that don't support
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* changing the parent can override the setter to throw an error.
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*
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* Example usage:
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* <pre>
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* var source = new goog.events.EventTarget();
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* function handleEvent(e) {
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* alert('Type: ' + e.type + '; Target: ' + e.target);
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* }
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* source.listen('foo', handleEvent);
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* // Or: goog.events.listen(source, 'foo', handleEvent);
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* ...
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* source.dispatchEvent('foo'); // will call handleEvent
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* ...
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* source.unlisten('foo', handleEvent);
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* // Or: goog.events.unlisten(source, 'foo', handleEvent);
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* </pre>
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*
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* @constructor
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* @extends {goog.Disposable}
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* @implements {goog.events.Listenable}
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*/
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goog.events.EventTarget = function() {
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goog.Disposable.call(this);
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/**
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* Maps of event type to an array of listeners.
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* @private {!goog.events.ListenerMap}
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*/
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this.eventTargetListeners_ = new goog.events.ListenerMap(this);
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/**
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* The object to use for event.target. Useful when mixing in an
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* EventTarget to another object.
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* @private {!Object}
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*/
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this.actualEventTarget_ = this;
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/**
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* Parent event target, used during event bubbling.
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*
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* TODO(chrishenry): Change this to goog.events.Listenable. This
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* currently breaks people who expect getParentEventTarget to return
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* goog.events.EventTarget.
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*
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* @private {goog.events.EventTarget}
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*/
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this.parentEventTarget_ = null;
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};
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goog.inherits(goog.events.EventTarget, goog.Disposable);
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goog.events.Listenable.addImplementation(goog.events.EventTarget);
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/**
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* An artificial cap on the number of ancestors you can have. This is mainly
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* for loop detection.
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* @const {number}
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* @private
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*/
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goog.events.EventTarget.MAX_ANCESTORS_ = 1000;
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/**
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* Returns the parent of this event target to use for bubbling.
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*
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* @return {goog.events.EventTarget} The parent EventTarget or null if
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* there is no parent.
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* @override
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*/
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goog.events.EventTarget.prototype.getParentEventTarget = function() {
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return this.parentEventTarget_;
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};
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/**
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* Sets the parent of this event target to use for capture/bubble
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* mechanism.
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* @param {goog.events.EventTarget} parent Parent listenable (null if none).
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*/
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goog.events.EventTarget.prototype.setParentEventTarget = function(parent) {
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this.parentEventTarget_ = parent;
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};
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/**
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* Adds an event listener to the event target. The same handler can only be
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* added once per the type. Even if you add the same handler multiple times
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* using the same type then it will only be called once when the event is
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* dispatched.
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*
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* @param {string|!goog.events.EventId} type The type of the event to listen for
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* @param {function(?):?|{handleEvent:function(?):?}|null} handler The function
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* to handle the event. The handler can also be an object that implements
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* the handleEvent method which takes the event object as argument.
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* @param {boolean=} opt_capture In DOM-compliant browsers, this determines
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* whether the listener is fired during the capture or bubble phase
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* of the event.
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* @param {Object=} opt_handlerScope Object in whose scope to call
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* the listener.
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* @deprecated Use {@code #listen} instead, when possible. Otherwise, use
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* {@code goog.events.listen} if you are passing Object
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* (instead of Function) as handler.
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*/
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goog.events.EventTarget.prototype.addEventListener = function(
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type, handler, opt_capture, opt_handlerScope) {
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goog.events.listen(this, type, handler, opt_capture, opt_handlerScope);
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};
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/**
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* Removes an event listener from the event target. The handler must be the
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* same object as the one added. If the handler has not been added then
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* nothing is done.
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*
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* @param {string} type The type of the event to listen for.
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* @param {function(?):?|{handleEvent:function(?):?}|null} handler The function
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* to handle the event. The handler can also be an object that implements
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* the handleEvent method which takes the event object as argument.
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* @param {boolean=} opt_capture In DOM-compliant browsers, this determines
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* whether the listener is fired during the capture or bubble phase
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* of the event.
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* @param {Object=} opt_handlerScope Object in whose scope to call
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* the listener.
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* @deprecated Use {@code #unlisten} instead, when possible. Otherwise, use
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* {@code goog.events.unlisten} if you are passing Object
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* (instead of Function) as handler.
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*/
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goog.events.EventTarget.prototype.removeEventListener = function(
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type, handler, opt_capture, opt_handlerScope) {
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goog.events.unlisten(this, type, handler, opt_capture, opt_handlerScope);
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};
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/** @override */
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goog.events.EventTarget.prototype.dispatchEvent = function(e) {
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this.assertInitialized_();
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var ancestorsTree, ancestor = this.getParentEventTarget();
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if (ancestor) {
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ancestorsTree = [];
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var ancestorCount = 1;
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for (; ancestor; ancestor = ancestor.getParentEventTarget()) {
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ancestorsTree.push(ancestor);
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goog.asserts.assert(
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(++ancestorCount < goog.events.EventTarget.MAX_ANCESTORS_),
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'infinite loop');
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}
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}
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return goog.events.EventTarget.dispatchEventInternal_(
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this.actualEventTarget_, e, ancestorsTree);
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};
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/**
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* Removes listeners from this object. Classes that extend EventTarget may
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* need to override this method in order to remove references to DOM Elements
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* and additional listeners.
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* @override
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*/
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goog.events.EventTarget.prototype.disposeInternal = function() {
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goog.events.EventTarget.superClass_.disposeInternal.call(this);
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this.removeAllListeners();
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this.parentEventTarget_ = null;
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};
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/** @override */
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goog.events.EventTarget.prototype.listen = function(
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type, listener, opt_useCapture, opt_listenerScope) {
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this.assertInitialized_();
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return this.eventTargetListeners_.add(
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String(type), listener, false /* callOnce */, opt_useCapture,
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opt_listenerScope);
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};
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/** @override */
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goog.events.EventTarget.prototype.listenOnce = function(
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type, listener, opt_useCapture, opt_listenerScope) {
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return this.eventTargetListeners_.add(
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String(type), listener, true /* callOnce */, opt_useCapture,
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opt_listenerScope);
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};
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/** @override */
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goog.events.EventTarget.prototype.unlisten = function(
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type, listener, opt_useCapture, opt_listenerScope) {
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return this.eventTargetListeners_.remove(
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String(type), listener, opt_useCapture, opt_listenerScope);
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};
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/** @override */
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goog.events.EventTarget.prototype.unlistenByKey = function(key) {
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return this.eventTargetListeners_.removeByKey(key);
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};
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/** @override */
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goog.events.EventTarget.prototype.removeAllListeners = function(opt_type) {
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// TODO(chrishenry): Previously, removeAllListeners can be called on
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// uninitialized EventTarget, so we preserve that behavior. We
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// should remove this when usages that rely on that fact are purged.
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if (!this.eventTargetListeners_) {
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return 0;
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}
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return this.eventTargetListeners_.removeAll(opt_type);
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};
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/** @override */
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goog.events.EventTarget.prototype.fireListeners = function(
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type, capture, eventObject) {
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// TODO(chrishenry): Original code avoids array creation when there
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// is no listener, so we do the same. If this optimization turns
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// out to be not required, we can replace this with
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// getListeners(type, capture) instead, which is simpler.
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var listenerArray = this.eventTargetListeners_.listeners[String(type)];
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if (!listenerArray) {
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return true;
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}
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listenerArray = listenerArray.concat();
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var rv = true;
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for (var i = 0; i < listenerArray.length; ++i) {
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var listener = listenerArray[i];
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// We might not have a listener if the listener was removed.
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if (listener && !listener.removed && listener.capture == capture) {
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var listenerFn = listener.listener;
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var listenerHandler = listener.handler || listener.src;
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if (listener.callOnce) {
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this.unlistenByKey(listener);
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}
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rv = listenerFn.call(listenerHandler, eventObject) !== false && rv;
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}
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}
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return rv && eventObject.returnValue_ != false;
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};
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/** @override */
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goog.events.EventTarget.prototype.getListeners = function(type, capture) {
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return this.eventTargetListeners_.getListeners(String(type), capture);
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};
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/** @override */
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goog.events.EventTarget.prototype.getListener = function(
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type, listener, capture, opt_listenerScope) {
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return this.eventTargetListeners_.getListener(
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String(type), listener, capture, opt_listenerScope);
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};
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/** @override */
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goog.events.EventTarget.prototype.hasListener = function(
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opt_type, opt_capture) {
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var id = goog.isDef(opt_type) ? String(opt_type) : undefined;
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return this.eventTargetListeners_.hasListener(id, opt_capture);
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};
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/**
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* Sets the target to be used for {@code event.target} when firing
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* event. Mainly used for testing. For example, see
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* {@code goog.testing.events.mixinListenable}.
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* @param {!Object} target The target.
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*/
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goog.events.EventTarget.prototype.setTargetForTesting = function(target) {
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this.actualEventTarget_ = target;
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};
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/**
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* Asserts that the event target instance is initialized properly.
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* @private
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*/
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goog.events.EventTarget.prototype.assertInitialized_ = function() {
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goog.asserts.assert(
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this.eventTargetListeners_,
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'Event target is not initialized. Did you call the superclass ' +
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'(goog.events.EventTarget) constructor?');
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};
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/**
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* Dispatches the given event on the ancestorsTree.
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*
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* @param {!Object} target The target to dispatch on.
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* @param {goog.events.Event|Object|string} e The event object.
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* @param {Array<goog.events.Listenable>=} opt_ancestorsTree The ancestors
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* tree of the target, in reverse order from the closest ancestor
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* to the root event target. May be null if the target has no ancestor.
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* @return {boolean} If anyone called preventDefault on the event object (or
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* if any of the listeners returns false) this will also return false.
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* @private
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*/
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goog.events.EventTarget.dispatchEventInternal_ = function(
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target, e, opt_ancestorsTree) {
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var type = e.type || /** @type {string} */ (e);
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// If accepting a string or object, create a custom event object so that
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// preventDefault and stopPropagation work with the event.
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if (goog.isString(e)) {
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e = new goog.events.Event(e, target);
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} else if (!(e instanceof goog.events.Event)) {
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var oldEvent = e;
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e = new goog.events.Event(type, target);
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goog.object.extend(e, oldEvent);
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} else {
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e.target = e.target || target;
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}
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var rv = true, currentTarget;
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// Executes all capture listeners on the ancestors, if any.
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if (opt_ancestorsTree) {
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for (var i = opt_ancestorsTree.length - 1; !e.propagationStopped_ && i >= 0;
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i--) {
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currentTarget = e.currentTarget = opt_ancestorsTree[i];
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rv = currentTarget.fireListeners(type, true, e) && rv;
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}
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}
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// Executes capture and bubble listeners on the target.
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if (!e.propagationStopped_) {
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currentTarget = /** @type {?} */ (e.currentTarget = target);
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rv = currentTarget.fireListeners(type, true, e) && rv;
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if (!e.propagationStopped_) {
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rv = currentTarget.fireListeners(type, false, e) && rv;
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}
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}
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// Executes all bubble listeners on the ancestors, if any.
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if (opt_ancestorsTree) {
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for (i = 0; !e.propagationStopped_ && i < opt_ancestorsTree.length; i++) {
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currentTarget = e.currentTarget = opt_ancestorsTree[i];
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rv = currentTarget.fireListeners(type, false, e) && rv;
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}
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}
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return rv;
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};
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