source: imaps-frontend/node_modules/find-cache-dir/node_modules/yocto-queue/index.js

/*
How it works:
`this.#head` is an instance of `Node` which keeps track of its current value and nests another instance of `Node` that keeps the value that comes after it. When a value is provided to `.enqueue()`, the code needs to iterate through `this.#head`, going deeper and deeper to find the last value. However, iterating through every single item is slow. This problem is solved by saving a reference to the last value as `this.#tail` so that it can reference it to add a new value.
*/

class Node {
        value;
        next;

        constructor(value) {
                this.value = value;
        }
}

export default class Queue {
        #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;
        }

        peek() {
                if (!this.#head) {
                        return;
                }

                return this.#head.value;

                // TODO: Node.js 18.
                // return this.#head?.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;
                }
        }
}