src/queue.ts

   1 // Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 /**
   4  * Queue
   5  *
   6  * @typeParam T - Type of queue items.
   7  */
   8 export class Queue<T> {
   9   private items: Record<number, T>
  10   private head: number
  11   private tail: number
  12
  13   public constructor () {
  14     this.items = {}
  15     this.head = 0
  16     this.tail = 0
  17   }
  18
  19   /**
  20    * Get the size of the queue.
  21    *
  22    * @returns The size of the queue.
  23    * @readonly
  24    */
  25   public get size (): number {
  26     return this.tail - this.head
  27   }
  28
  29   /**
  30    * Enqueue an item.
  31    *
  32    * @param item - Item to enqueue.
  33    * @returns The new size of the queue.
  34    */
  35   public enqueue (item: T): number {
  36     this.items[this.tail] = item
  37     this.tail++
  38     return this.size
  39   }
  40
  41   /**
  42    * Dequeue an item.
  43    *
  44    * @returns The dequeued item or `undefined` if the queue is empty.
  45    */
  46   public dequeue (): T | undefined {
  47     if (this.size <= 0) return undefined
  48     const item = this.items[this.head]
  49     // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
  50     delete this.items[this.head]
  51     this.head++
  52     if (this.head === this.tail) {
  53       this.head = 0
  54       this.tail = 0
  55     }
  56     return item
  57   }
  58
  59   /**
  60    * Peek at the first item.
  61    */
  62   public peek (): T | undefined {
  63     if (this.size <= 0) return undefined
  64     return this.items[this.head]
  65   }
  66 }