130 lines
4.1 KiB
JavaScript
130 lines
4.1 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 An implementation of {@code Observable} that can be
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* used as base class or composed into another class that wants to
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* implement {@code Observable}.
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*/
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goog.provide('goog.labs.observe.SimpleObservable');
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goog.require('goog.Disposable');
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goog.require('goog.array');
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goog.require('goog.asserts');
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goog.require('goog.labs.observe.Notice');
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goog.require('goog.labs.observe.Observable');
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goog.require('goog.labs.observe.Observer');
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goog.require('goog.object');
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/**
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* A simple implementation of {@code goog.labs.observe.Observable} that can
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* be used as a standalone observable or as a base class for other
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* observable object.
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*
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* When another class wants to implement observable without extending
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* {@code SimpleObservable}, they can create an instance of
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* {@code SimpleObservable}, specifying {@code opt_actualObservable},
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* and delegate to the instance. Here is a trivial example:
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*
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* <pre>
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* ClassA = function() {
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* goog.base(this);
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* this.observable_ = new SimpleObservable(this);
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* this.registerDisposable(this.observable_);
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* };
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* goog.inherits(ClassA, goog.Disposable);
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*
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* ClassA.prototype.observe = function(observer) {
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* this.observable_.observe(observer);
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* };
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*
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* ClassA.prototype.unobserve = function(observer) {
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* this.observable_.unobserve(observer);
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* };
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*
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* ClassA.prototype.notify = function(opt_data) {
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* this.observable_.notify(opt_data);
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* };
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* </pre>
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*
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* @param {!goog.labs.observe.Observable=} opt_actualObservable
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* Optional observable object. Defaults to 'this'. When used as
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* base class, the parameter need not be given. It is only useful
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* when using this class to implement implement {@code Observable}
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* interface on another object, see example above.
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* @constructor
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* @implements {goog.labs.observe.Observable}
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* @extends {goog.Disposable}
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*/
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goog.labs.observe.SimpleObservable = function(opt_actualObservable) {
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goog.base(this);
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/**
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* @type {!goog.labs.observe.Observable}
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* @private
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*/
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this.actualObservable_ = opt_actualObservable || this;
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/**
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* Observers registered on this object.
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* @type {!Array.<!goog.labs.observe.Observer>}
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* @private
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*/
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this.observers_ = [];
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};
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goog.inherits(goog.labs.observe.SimpleObservable, goog.Disposable);
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/** @override */
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goog.labs.observe.SimpleObservable.prototype.observe = function(observer) {
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goog.asserts.assert(!this.isDisposed());
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// Registers the (type, observer) only if it has not been previously
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// registered.
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var shouldRegisterObserver = !goog.array.some(this.observers_, goog.partial(
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goog.labs.observe.Observer.equals, observer));
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if (shouldRegisterObserver) {
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this.observers_.push(observer);
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}
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return shouldRegisterObserver;
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};
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/** @override */
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goog.labs.observe.SimpleObservable.prototype.unobserve = function(observer) {
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goog.asserts.assert(!this.isDisposed());
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return goog.array.removeIf(this.observers_, goog.partial(
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goog.labs.observe.Observer.equals, observer));
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};
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/** @override */
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goog.labs.observe.SimpleObservable.prototype.notify = function(opt_data) {
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goog.asserts.assert(!this.isDisposed());
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var notice = new goog.labs.observe.Notice(this.actualObservable_, opt_data);
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goog.array.forEach(
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goog.array.clone(this.observers_), function(observer) {
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observer.notify(notice);
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});
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};
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/** @override */
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goog.labs.observe.SimpleObservable.prototype.disposeInternal = function() {
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this.observers_.length = 0;
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};
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