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// Copyright 2007 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 Definition of the goog.async.Throttle class.
*
* @see ../demos/timers.html
*/
goog.provide('goog.Throttle');
goog.provide('goog.async.Throttle');
goog.require('goog.Disposable');
goog.require('goog.Timer');
/**
* Throttle will perform an action that is passed in no more than once
* per interval (specified in milliseconds). If it gets multiple signals
* to perform the action while it is waiting, it will only perform the action
* once at the end of the interval.
* @param {function(this: T, ...?)} listener Function to callback when the
* action is triggered.
* @param {number} interval Interval over which to throttle. The listener can
* only be called once per interval.
* @param {T=} opt_handler Object in whose scope to call the listener.
* @constructor
* @struct
* @extends {goog.Disposable}
* @final
* @template T
*/
goog.async.Throttle = function(listener, interval, opt_handler) {
goog.async.Throttle.base(this, 'constructor');
/**
* Function to callback
* @type {function(this: T, ...?)}
* @private
*/
this.listener_ =
opt_handler != null ? goog.bind(listener, opt_handler) : listener;
/**
* Interval for the throttle time
* @type {number}
* @private
*/
this.interval_ = interval;
/**
* Cached callback function invoked after the throttle timeout completes
* @type {Function}
* @private
*/
this.callback_ = goog.bind(this.onTimer_, this);
/**
* The last arguments passed into {@code fire}.
* @private {!IArrayLike}
*/
this.args_ = [];
};
goog.inherits(goog.async.Throttle, goog.Disposable);
/**
* A deprecated alias.
* @deprecated Use goog.async.Throttle instead.
* @constructor
* @final
*/
goog.Throttle = goog.async.Throttle;
/**
* Indicates that the action is pending and needs to be fired.
* @type {boolean}
* @private
*/
goog.async.Throttle.prototype.shouldFire_ = false;
/**
* Indicates the count of nested pauses currently in effect on the throttle.
* When this count is not zero, fired actions will be postponed until the
* throttle is resumed enough times to drop the pause count to zero.
* @type {number}
* @private
*/
goog.async.Throttle.prototype.pauseCount_ = 0;
/**
* Timer for scheduling the next callback
* @type {?number}
* @private
*/
goog.async.Throttle.prototype.timer_ = null;
/**
* Notifies the throttle that the action has happened. It will throttle the call
* so that the callback is not called too often according to the interval
* parameter passed to the constructor, passing the arguments from the last call
* of this function into the throttled function.
* @param {...?} var_args Arguments to pass on to the throttled function.
*/
goog.async.Throttle.prototype.fire = function(var_args) {
this.args_ = arguments;
if (!this.timer_ && !this.pauseCount_) {
this.doAction_();
} else {
this.shouldFire_ = true;
}
};
/**
* Cancels any pending action callback. The throttle can be restarted by
* calling {@link #fire}.
*/
goog.async.Throttle.prototype.stop = function() {
if (this.timer_) {
goog.Timer.clear(this.timer_);
this.timer_ = null;
this.shouldFire_ = false;
this.args_ = [];
}
};
/**
* Pauses the throttle. All pending and future action callbacks will be
* delayed until the throttle is resumed. Pauses can be nested.
*/
goog.async.Throttle.prototype.pause = function() {
this.pauseCount_++;
};
/**
* Resumes the throttle. If doing so drops the pausing count to zero, pending
* action callbacks will be executed as soon as possible, but still no sooner
* than an interval's delay after the previous call. Future action callbacks
* will be executed as normal.
*/
goog.async.Throttle.prototype.resume = function() {
this.pauseCount_--;
if (!this.pauseCount_ && this.shouldFire_ && !this.timer_) {
this.shouldFire_ = false;
this.doAction_();
}
};
/** @override */
goog.async.Throttle.prototype.disposeInternal = function() {
goog.async.Throttle.base(this, 'disposeInternal');
this.stop();
};
/**
* Handler for the timer to fire the throttle
* @private
*/
goog.async.Throttle.prototype.onTimer_ = function() {
this.timer_ = null;
if (this.shouldFire_ && !this.pauseCount_) {
this.shouldFire_ = false;
this.doAction_();
}
};
/**
* Calls the callback
* @private
*/
goog.async.Throttle.prototype.doAction_ = function() {
this.timer_ = goog.Timer.callOnce(this.callback_, this.interval_);
this.listener_.apply(null, this.args_);
};
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