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