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// Copyright 2012 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview A set of observations. This set provides a convenient
* means of observing many observables at once.
*
* This is similar in purpose to {@code goog.events.EventHandler}.
*
*/
goog.provide('goog.labs.observe.ObservationSet');
goog.require('goog.array');
goog.require('goog.labs.observe.Observer');
/**
* A set of observations. An observation is defined by an observable
* and an observer. The set keeps track of observations and
* allows their removal.
* @param {!Object=} opt_defaultScope Optional function scope to use
* when using {@code observeWithFunction} and
* {@code unobserveWithFunction}.
* @constructor
*/
goog.labs.observe.ObservationSet = function(opt_defaultScope) {
/**
* @type {!Array.<!goog.labs.observe.ObservationSet.Observation_>}
* @private
*/
this.storedObservations_ = [];
/**
* @type {!Object|undefined}
* @private
*/
this.defaultScope_ = opt_defaultScope;
};
/**
* Observes the given observer on the observable.
* @param {!goog.labs.observe.Observable} observable The observable to
* observe on.
* @param {!goog.labs.observe.Observer} observer The observer.
* @return {boolean} True if the observer is successfully registered.
*/
goog.labs.observe.ObservationSet.prototype.observe = function(
observable, observer) {
var success = observable.observe(observer);
if (success) {
this.storedObservations_.push(
new goog.labs.observe.ObservationSet.Observation_(
observable, observer));
}
return success;
};
/**
* Observes the given function on the observable.
* @param {!goog.labs.observe.Observable} observable The observable to
* observe on.
* @param {function(!goog.labs.observe.Notice)} fn The handler function.
* @param {!Object=} opt_scope Optional scope.
* @return {goog.labs.observe.Observer} The registered observer object.
* If the observer is not successfully registered, this will be null.
*/
goog.labs.observe.ObservationSet.prototype.observeWithFunction = function(
observable, fn, opt_scope) {
var observer = goog.labs.observe.Observer.fromFunction(
fn, opt_scope || this.defaultScope_);
if (this.observe(observable, observer)) {
return observer;
}
return null;
};
/**
* Unobserves the given observer from the observable.
* @param {!goog.labs.observe.Observable} observable The observable to
* unobserve from.
* @param {!goog.labs.observe.Observer} observer The observer.
* @return {boolean} True if the observer is successfully removed.
*/
goog.labs.observe.ObservationSet.prototype.unobserve = function(
observable, observer) {
var removed = goog.array.removeIf(
this.storedObservations_, function(o) {
return o.observable == observable &&
goog.labs.observe.Observer.equals(o.observer, observer);
});
if (removed) {
observable.unobserve(observer);
}
return removed;
};
/**
* Unobserves the given function from the observable.
* @param {!goog.labs.observe.Observable} observable The observable to
* unobserve from.
* @param {function(!goog.labs.observe.Notice)} fn The handler function.
* @param {!Object=} opt_scope Optional scope.
* @return {boolean} True if the observer is successfully removed.
*/
goog.labs.observe.ObservationSet.prototype.unobserveWithFunction = function(
observable, fn, opt_scope) {
var observer = goog.labs.observe.Observer.fromFunction(
fn, opt_scope || this.defaultScope_);
return this.unobserve(observable, observer);
};
/**
* Removes all observations registered through this set.
*/
goog.labs.observe.ObservationSet.prototype.removeAll = function() {
goog.array.forEach(this.storedObservations_, function(observation) {
var observable = observation.observable;
var observer = observation.observer;
observable.unobserve(observer);
});
};
/**
* A representation of an observation, which is defined uniquely by
* the observable and observer.
* @param {!goog.labs.observe.Observable} observable The observable.
* @param {!goog.labs.observe.Observer} observer The observer.
* @constructor
* @private
*/
goog.labs.observe.ObservationSet.Observation_ = function(
observable, observer) {
this.observable = observable;
this.observer = observer;
};
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