simple immutable class library

immutable.ts

export class ImmutableUtility<T> {
  #draft: any

  constructor(array: Array<T>) {
    if (array.length === 0) {
      throw new Error('Out of bounds...')
    }

    this.#draft = [...array]
  }

  get all(): Array<T> {
    return this.#draft
  }

  public has(item: any) {
    return this.#draft.includes(item)
  }

  public peek() {
    return this.#draft[this.#draft.length - 1]
  }

  public splice(start: number, count: number, ...item: Array<T>) {
    return [...this.#draft.slice(0, start), ...item, ...this.#draft.slice(start + count)]
  }

  public insert(item: any, pos: 'before' | 'after' | number) {
    switch (pos) {
      case 'before':
        this.#draft = [item, ...this.#draft]
        break
      case 'after':
        this.#draft = [...this.#draft, item]
        break
      default:
        if (typeof pos !== 'number') {
          throw new Error(`Position cannot be a ${typeof pos}.`)
        }

        this.#draft = this.splice(0, pos, item)
        break
    }
  }

  public remove(index: number) {
    return (this.#draft = [...this.#draft.slice(0, index), ...this.#draft.slice(index + 1)])
  }

  public reverse() {
    return (this.#draft = [...this.#draft].reverse())
  }

  public produce(handler: (draft: Array<T>) => void): void {
    if (typeof handler !== 'function') return
    this.#draft = [...this.#draft, handler(this.#draft)]
  }

  // measure(cb: any) {
  //   const begin = (globalThis || window).performance.now()
  //   cb()
  //   const end = (globalThis || window).performance.now()

  //   console.log(cb(), `-> it took ${(end - begin).toFixed(3)} ms`)
  // }
}

export function Immutable<T>(array: Array<T>): ImmutableUtility<T> {
  const immutable = new ImmutableUtility<T>(array)
  return immutable
}

export default Immutable