@figliolia/data-structures/src/QuickStack.ts

Efficient data structures for every day programming

import { QuickList } from "./QuickList";

/**
 * Quick Stack
 *
 * A wrapper around the native Map that assigns an
 * auto-incrementing ID to each value added. It provides
 * a Stack-like interface with the ability to access and
 * remove items in 0(1) time
 *
 * ```typescript
 * const stack = new QuickStack<() => void>();
 * const uniqueID = stack.push(() => {});
 *
 * const FN = stack.pop() // Remove and return the first item on the stack
 * const FN = stack.get(uniqueID); // Get an entry by ID
 * stack.delete(uniqueID) // Delete an entry by ID
 * ```
 */
export class QuickStack<T> extends QuickList<T> {
  /**
   * Pop
   *
   * Removes and returns the top entry in the stack
   */
  public pop() {
    for (const [ID, item] of this) {
      this.delete(ID);
      return item;
    }
  }

  /**
   * Peek
   *
   * Returns the top entry in the stack
   */
  public peek() {
    for (const entry of this) {
      return entry;
    }
  }

  // @ts-ignore
  *[Symbol.iterator]() {
    const items = Array.from(this.storage.entries());
    const { length } = items;
    for (let i = length - 1; i > -1; i--) {
      yield items[i];
    }
  }
}