src/circular-array.ts

   1 // Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 const DEFAULT_CIRCULAR_ARRAY_SIZE = 1024
   4
   5 /**
   6  * Array with a maximum length and shifting items when full.
   7  *
   8  * @internal
   9  */
  10 export class CircularArray<T> extends Array<T> {
  11   public size: number
  12
  13   constructor (size: number = DEFAULT_CIRCULAR_ARRAY_SIZE, ...items: T[]) {
  14     super()
  15     this.checkSize(size)
  16     this.size = size
  17     if (arguments.length > 1) {
  18       this.push(...items)
  19     }
  20   }
  21
  22   /** @inheritDoc */
  23   public push (...items: T[]): number {
  24     const length = super.push(...items)
  25     if (length > this.size) {
  26       super.splice(0, length - this.size)
  27     }
  28     return this.length
  29   }
  30
  31   /** @inheritDoc */
  32   public unshift (...items: T[]): number {
  33     const length = super.unshift(...items)
  34     if (length > this.size) {
  35       super.splice(this.size, items.length)
  36     }
  37     return this.length
  38   }
  39
  40   /** @inheritDoc */
  41   public concat (...items: Array<T | ConcatArray<T>>): CircularArray<T> {
  42     const concatenatedCircularArray = super.concat(
  43       items as T[]
  44     ) as CircularArray<T>
  45     concatenatedCircularArray.size = this.size
  46     if (concatenatedCircularArray.length > concatenatedCircularArray.size) {
  47       concatenatedCircularArray.splice(
  48         0,
  49         concatenatedCircularArray.length - concatenatedCircularArray.size
  50       )
  51     }
  52     return concatenatedCircularArray
  53   }
  54
  55   /** @inheritDoc */
  56   public splice (
  57     start: number,
  58     deleteCount?: number,
  59     ...items: T[]
  60   ): CircularArray<T> {
  61     let itemsRemoved: T[] = []
  62     if (arguments.length >= 3 && deleteCount != null) {
  63       itemsRemoved = super.splice(start, deleteCount, ...items)
  64       if (this.length > this.size) {
  65         const itemsOverflowing = super.splice(0, this.length - this.size)
  66         itemsRemoved = new CircularArray<T>(
  67           itemsRemoved.length + itemsOverflowing.length,
  68           ...itemsRemoved,
  69           ...itemsOverflowing
  70         )
  71       }
  72     } else if (arguments.length === 2) {
  73       itemsRemoved = super.splice(start, deleteCount)
  74     } else {
  75       itemsRemoved = super.splice(start)
  76     }
  77     return itemsRemoved as CircularArray<T>
  78   }
  79
  80   public resize (size: number): void {
  81     this.checkSize(size)
  82     if (size === 0) {
  83       this.length = 0
  84     } else if (size < this.size) {
  85       for (let i = size; i < this.size; i++) {
  86         super.pop()
  87       }
  88     }
  89     this.size = size
  90   }
  91
  92   public empty (): boolean {
  93     return this.length === 0
  94   }
  95
  96   public full (): boolean {
  97     return this.length === this.size
  98   }
  99
 100   private checkSize (size: number): void {
 101     if (!Number.isSafeInteger(size)) {
 102       throw new TypeError(
 103         `Invalid circular array size: ${size} is not a safe integer`
 104       )
 105     }
 106     if (size < 0) {
 107       throw new RangeError(`Invalid circular array size: ${size} < 0`)
 108     }
 109   }
 110 }