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51 lines
1.0 KiB
51 lines
1.0 KiB
/* |
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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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