mirror of https://github.com/jkjoy/sunpeiwen.git
52 lines
1.0 KiB
JavaScript
52 lines
1.0 KiB
JavaScript
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/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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/**
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* @template T
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*/
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class Queue {
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/**
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* @param {Iterable<T>=} items The initial elements.
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*/
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constructor(items) {
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/** @private @type {Set<T>} */
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this._set = new Set(items);
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/** @private @type {Iterator<T>} */
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this._iterator = this._set[Symbol.iterator]();
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}
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/**
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* Returns the number of elements in this queue.
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* @returns {number} The number of elements in this queue.
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*/
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get length() {
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return this._set.size;
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}
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/**
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* Appends the specified element to this queue.
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* @param {T} item The element to add.
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* @returns {void}
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*/
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enqueue(item) {
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this._set.add(item);
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}
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/**
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* Retrieves and removes the head of this queue.
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* @returns {T | undefined} The head of the queue of `undefined` if this queue is empty.
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*/
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dequeue() {
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const result = this._iterator.next();
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if (result.done) return undefined;
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this._set.delete(result.value);
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return result.value;
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}
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}
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module.exports = Queue;
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