101 lines
3.0 KiB
JavaScript
101 lines
3.0 KiB
JavaScript
// Copyright 2012 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 Provide definition of an observer. This is meant to
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* be used with {@code goog.labs.observe.Observable}.
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*
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* This file also provides convenient functions to compare and create
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* Observer objects.
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*
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*/
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goog.provide('goog.labs.observe.Observer');
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/**
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* A class implementing {@code Observer} may be informed of changes in
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* observable object.
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* @see {goog.labs.observe.Observable}
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* @interface
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*/
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goog.labs.observe.Observer = function() {};
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/**
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* Notifies the observer of changes to the observable object.
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* @param {!goog.labs.observe.Notice} notice The notice object.
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*/
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goog.labs.observe.Observer.prototype.notify;
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/**
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* Whether this observer is equal to the given observer.
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* @param {!goog.labs.observe.Observer} observer The observer to compare with.
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* @return {boolean} Whether the two observers are equal.
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*/
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goog.labs.observe.Observer.prototype.equals;
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/**
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* @param {!goog.labs.observe.Observer} observer1 Observer to compare.
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* @param {!goog.labs.observe.Observer} observer2 Observer to compare.
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* @return {boolean} Whether observer1 and observer2 are equal, as
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* determined by the first observer1's {@code equals} method.
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*/
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goog.labs.observe.Observer.equals = function(observer1, observer2) {
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return observer1 == observer2 || observer1.equals(observer2);
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};
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/**
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* Creates an observer that calls the given function.
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* @param {function(!goog.labs.observe.Notice)} fn Function to be converted.
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* @param {!Object=} opt_scope Optional scope to execute the function.
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* @return {!goog.labs.observe.Observer} An observer object.
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*/
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goog.labs.observe.Observer.fromFunction = function(fn, opt_scope) {
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return new goog.labs.observe.Observer.FunctionObserver_(fn, opt_scope);
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};
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/**
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* An observer that calls the given function on {@code notify}.
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* @param {function(!goog.labs.observe.Notice)} fn Function to delegate to.
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* @param {!Object=} opt_scope Optional scope to execute the function.
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* @constructor
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* @implements {goog.labs.observe.Observer}
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* @private
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*/
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goog.labs.observe.Observer.FunctionObserver_ = function(fn, opt_scope) {
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this.fn_ = fn;
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this.scope_ = opt_scope;
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};
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/** @override */
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goog.labs.observe.Observer.FunctionObserver_.prototype.notify = function(
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notice) {
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this.fn_.call(this.scope_, notice);
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};
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/** @override */
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goog.labs.observe.Observer.FunctionObserver_.prototype.equals = function(
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observer) {
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return this.fn_ === observer.fn_ && this.scope_ === observer.scope_;
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};
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