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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import {assert} from 'chrome://resources/js/assert.m.js';
import {PromiseResolver} from 'chrome://resources/js/promise_resolver.m.js';
/**
* @fileoverview A debouncer which fires the given callback after a delay. The
* delay can be refreshed by calling restartTimeout. Resetting the timeout with
* no delay moves the callback to the end of the task queue.
*/
export class Debouncer {
/** @param {!function()} callback */
constructor(callback) {
/** @private {!function()} */
this.callback_ = callback;
/** @private {!Object} */
this.timerProxy_ = window;
/** @private {?number} */
this.timer_ = null;
/** @private {!function()} */
this.boundTimerCallback_ = this.timerCallback_.bind(this);
/** @private {boolean} */
this.isDone_ = false;
/** @private {!PromiseResolver} */
this.promiseResolver_ = new PromiseResolver();
}
/**
* Starts the timer for the callback, cancelling the old timer if there is
* one.
* @param {number=} delay
*/
restartTimeout(delay) {
assert(!this.isDone_);
this.cancelTimeout_();
this.timer_ =
this.timerProxy_.setTimeout(this.boundTimerCallback_, delay || 0);
}
/**
* @return {boolean} True if the Debouncer has finished processing.
*/
done() {
return this.isDone_;
}
/**
* @return {!Promise} Promise which resolves immediately after the callback.
*/
get promise() {
return this.promiseResolver_.promise;
}
/**
* Resets the debouncer as if it had been newly instantiated.
*/
reset() {
this.isDone_ = false;
this.promiseResolver_ = new PromiseResolver();
this.cancelTimeout_();
}
/**
* Cancel the timer callback, which can be restarted by calling
* restartTimeout().
* @private
*/
cancelTimeout_() {
if (this.timer_) {
this.timerProxy_.clearTimeout(this.timer_);
}
}
/** @private */
timerCallback_() {
this.isDone_ = true;
this.callback_.call();
this.promiseResolver_.resolve();
}
}
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