queue.ts

queue.ts

export enum QueueType {
  FIRST_IN_FIRST_OUT = "FIRST_IN_FIRST_OUT",
  LAST_IN_FIRST_OUT = "LAST_IN_FIRST_OUT",
}
export class Queue<T> {
  private type: QueueType;
  private data: T[];
  constructor({ type = QueueType.LAST_IN_FIRST_OUT }: { type: QueueType }) {
    this.type = type;
    this.data = []; // clear it out
  }

  public push = (item: T) => {
    this.data.push(item);
  };
  public pop = () => {
    // handle fifo
    if (this.type === QueueType.FIRST_IN_FIRST_OUT) {
      const [firstItem, ...otherItems] = this.data;
      this.data = otherItems;
      return firstItem;
    }

    // handle lifo
    if (this.type === QueueType.LAST_IN_FIRST_OUT) {
      const lastItem = this.data.slice(-1)[0];
      this.data = this.data.slice(0, -1);
      return lastItem;
    }

    // if the above didn't handle it, probably an error
    throw new Error("unexpected queue type");
  };
  public popAll = () => {
    const items = this.data;
    this.data = [];
    return items;
  };
}