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47 lines
940 B
47 lines
940 B
4 years ago
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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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