class Collection {

#arr;

constructor(...args) {

// console.log(args, [...args], ...args);

this.#arr = Array.isArray(args[0]) ? args[0] : [...args];

// console.log(this.#arr);

}

push(val) {

this.#arr.push(val);

}

pop() {

return this.#arr.pop();

}

shift() {

return this.#arr.shift();

}

clear() {

this.#arr.length = 0;

}

get peek() {

if (this.constructor.name === 'Stack') return this.#arr[this.length - 1];

return this.#arr[0];

}

get isEmpty() {

return !this.#arr.length;

}

get length() {

return this.#arr.length;

}

// [Symbol.iterator]() {

// let idx = -1;

// return {

// next: () => {

// idx += 1;

// return { value: this.#arr[idx], done : !this.#arr[idx] }

// },

// };

// }

*[Symbol.iterator]() {

for (let idx = 0; idx < this.#arr.length; idx += 1) {

yield this.#arr[idx];

}

}

toArray() {

return [...this.#arr];

}

print(cb) {

if (cb) {

cb([...this.#arr].reverse());

return;

}

console.log('coll>>', this.#arr);

}

}

class Stack extends Collection {

print() {

super.print(arr => console.log('STACK>>\n', arr.join('\n ')));

}

}

class Queue extends Collection {

enqueue(val) {

super.push(val);

}

dequeue() {

return super.shift();

}

print() {

super.print(arr => console.log('QUEUE>> ->', arr.join(' -> '), '->'));

}

}

const stack = new Stack([1, 2]); // or new Stack([1,2]); // (1,2)

stack.push(3); // 추가하기

console.log('spop>>>', stack.pop()); // 마지막에 추가된 하나 꺼내기

stack.push(3);

const queue = new Queue([11, 22]);

queue.enqueue(33); // 추가하기

console.log('deq>>', queue.dequeue()); // 추가한지 가장 오래된 - 먼저 들어간 - 하나 꺼내기

queue.enqueue(44);

// console.log('speek=', stack.peek);

// console.log('qpeek=', queue.peek);

stack.print();

queue.print();