source: frontend/node_modules/yocto-queue/index.js

class Node {
        /// value;
        /// next;

        constructor(value) {
                this.value = value;

                // TODO: Remove this when targeting Node.js 12.
                this.next = undefined;
        }
}

class Queue {
        // TODO: Use private class fields when targeting Node.js 12.
        // #_head;
        // #_tail;
        // #_size;

        constructor() {
                this.clear();
        }

        enqueue(value) {
                const node = new Node(value);

                if (this._head) {
                        this._tail.next = node;
                        this._tail = node;
                } else {
                        this._head = node;
                        this._tail = node;
                }

                this._size++;
        }

        dequeue() {
                const current = this._head;
                if (!current) {
                        return;
                }

                this._head = this._head.next;
                this._size--;
                return current.value;
        }

        clear() {
                this._head = undefined;
                this._tail = undefined;
                this._size = 0;
        }

        get size() {
                return this._size;
        }

        * [Symbol.iterator]() {
                let current = this._head;

                while (current) {
                        yield current.value;
                        current = current.next;
                }
        }
}

module.exports = Queue;