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 export class CircularArray<T> extends Array<T> {
   9   public size: number
  10
  11   constructor (size: number = DEFAULT_CIRCULAR_ARRAY_SIZE, ...items: T[]) {
  12     super()
  13     this.checkSize(size)
  14     this.size = size
  15     if (arguments.length > 1) {
  16       this.push(...items)
  17     }
  18   }
  19
  20   /** @inheritdoc */
  21   public push (...items: T[]): number {
  22     const length = super.push(...items)
  23     if (length > this.size) {
  24       super.splice(0, length - this.size)
  25     }
  26     return this.length
  27   }
  28
  29   /** @inheritdoc */
  30   public unshift (...items: T[]): number {
  31     const length = super.unshift(...items)
  32     if (length > this.size) {
  33       super.splice(this.size, items.length)
  34     }
  35     return this.length
  36   }
  37
  38   /** @inheritdoc */
  39   public concat (...items: Array<T | ConcatArray<T>>): CircularArray<T> {
  40     const concatenatedCircularArray = super.concat(
  41       items as T[]
  42     ) as CircularArray<T>
  43     concatenatedCircularArray.size = this.size
  44     if (concatenatedCircularArray.length > concatenatedCircularArray.size) {
  45       concatenatedCircularArray.splice(
  46         0,
  47         concatenatedCircularArray.length - concatenatedCircularArray.size
  48       )
  49     }
  50     return concatenatedCircularArray
  51   }
  52
  53   /** @inheritdoc */
  54   public splice (start: number, deleteCount?: number, ...items: T[]): T[] {
  55     let itemsRemoved: T[]
  56     if (arguments.length >= 3 && deleteCount !== undefined) {
  57       itemsRemoved = super.splice(start, deleteCount)
  58       // FIXME: that makes the items insert not in place
  59       this.push(...items)
  60     } else if (arguments.length === 2) {
  61       itemsRemoved = super.splice(start, deleteCount)
  62     } else {
  63       itemsRemoved = super.splice(start)
  64     }
  65     return itemsRemoved
  66   }
  67
  68   public resize (size: number): void {
  69     this.checkSize(size)
  70     if (size === 0) {
  71       this.length = 0
  72     } else if (size < this.size) {
  73       for (let i = size; i < this.size; i++) {
  74         super.pop()
  75       }
  76     }
  77     this.size = size
  78   }
  79
  80   public empty (): boolean {
  81     return this.length === 0
  82   }
  83
  84   public full (): boolean {
  85     return this.length === this.size
  86   }
  87
  88   private checkSize (size: number): void {
  89     if (!Number.isSafeInteger(size)) {
  90       throw new TypeError(
  91         `Invalid circular array size: ${size} is not a safe integer`
  92       )
  93     }
  94     if (size < 0) {
  95       throw new RangeError(`Invalid circular array size: ${size} < 0`)
  96     }
  97   }
  98 }