[js][utility]add Queue

shared/utility/index.mjs

@@ -1 +1,2 @@
 export { areArrayBuffersEqual } from './buffer.mjs';
+export { Queue, QueueEmptyError } from './queue.mjs';

shared/utility/queue.mjs

@@ -0,0 +1,127 @@
+/**
+ * Represents a queue data structure.
+ * @class
+ */
+export class Queue {
+    /**
+     * Creates an instance of Queue.
+     * @constructor
+     */
+    constructor() {
+        /**
+         * The data array to store elements.
+         * @type {Array}
+         * @private
+         */
+        this.data = [];
+        /**
+         * The index of the front element in the queue.
+         * @type {number}
+         * @private
+         */
+        this.head = 0;
+    }
+
+    /**
+     * Retrieves the front element of the queue.
+     * @returns {*} The front element of the queue.
+     */
+    front() {
+        return this.data[this.head];
+    }
+
+    /**
+     * Retrieves the back element of the queue.
+     * @returns {*} The back element of the queue.
+     */
+    back() {
+        return this.data[this.data.length - 1];
+    }
+
+    /**
+     * Removes the back element from the queue.
+     * @throws {QueueEmptyError} Throws an error if the queue is empty.
+     */
+    popBack() {
+        if (this.data.length == this.head) {
+            throw new QueueEmptyError();
+        }
+        this.data.length -= 1;
+    }
+
+    /**
+     * Checks if the queue is empty.
+     * @returns {boolean} True if the queue is empty, otherwise false.
+     */
+    empty() {
+        return this.data.length == this.head;
+    }
+
+    /**
+     * Returns the size of the queue.
+     * @returns {number} The size of the queue.
+     */
+    size() {
+        return this.data.length - this.head;
+    }
+
+    /**
+     * Alias for the size() method.
+     * @type {number}
+     */
+    get length() {
+        return this.size();
+    }
+
+    /**
+     * Pushes elements into the queue.
+     * @param {...*} elements The elements to push into the queue.
+     */
+    push() {
+        this.data.push.apply(this.data, arguments);
+    }
+
+    /**
+     * Removes the front element from the queue.
+     * @throws {QueueEmptyError} Throws an error if the queue is empty.
+     */
+    popFront() {
+        if (this.empty()) { throw new QueueEmptyError();}
+
+        this.head += 1;
+        if (this.head == this.data.length) {
+            this.data = [];
+            this.head = 0;
+            return;
+        }
+        if (this.head >= this.data.length >> 1 && this.head >= 16) {
+            this.data = this.data.slice(this.head);
+            this.head = 0;
+        }
+    }
+
+    /**
+     * Returns an iterator that allows iterating through the elements of the queue.
+     * @returns {*} elements of the queue.
+     * @generator
+     */
+    *[Symbol.iterator]() {
+        for (let i = this.head; i < this.data.length; i += 1) {
+            yield this.data[i];
+        }
+    }
+}
+
+/**
+ * Represents an error thrown when attempting operations on an empty queue.
+ * @class
+ */
+export class QueueEmptyError extends Error {
+    /**
+     * Creates an instance of QueueEmptyError.
+     * @constructor
+     */
+    constructor() {
+        super('Queue is empty');
+    }
+}