linked-list-iterator.ts

class LinkedList<T> {
  value: T;
  rest: LinkedList<T> | null;

  constructor(value: T, rest: LinkedList<T> | null) {
    this.value = value;
    this.rest = rest;
  }

  get length(): number {
    return 1 + (this.rest ? this.rest.length : 0);
  }

  static fromArray<T>(array: T[]): LinkedList<T> | null {
    let result: LinkedList<T> | null = null;
    for (let i = array.length - 1; i >= 0; i--) {
      result = new this(array[i], result);
    }
    return result;
  }

  linkedListForIteration: LinkedList<T> | null = this;

  [Symbol.iterator](): Iterator<T> {
    const _this = this;

    return {
      next(): IteratorResult<T> {
        if (_this.linkedListForIteration === null) {
          return { value: undefined, done: true };
        }

        const valueToReturn = _this.linkedListForIteration.value;
        _this.linkedListForIteration = _this.linkedListForIteration.rest;

        return { value: valueToReturn, done: false };
      },
    };
  }
}

const linkedList = LinkedList.fromArray([1, 2, 3, 4, 5]);

// for (const value of linkedList) {
//   console.log(value)
// }

// const iterator = linkedList[Symbol.iterator]();

// console.info(iterator.next()); // { value: 1, done: false }
// console.info(iterator.next()); // { value: 2, done: false }
// console.info(iterator.next()); // { value: 3, done: false }
// console.info(iterator.next()); // { value: 4, done: false }
// console.info(iterator.next()); // { value: 5, done: false }
// console.info(iterator.next()); // { value: undefined, done: true }