src/utils/CircularArray.ts

   1 // Copyright Jerome Benoit. 2021. All Rights Reserved.
   2
   3 export const DEFAULT_CIRCULAR_ARRAY_SIZE = Number.MAX_SAFE_INTEGER;
   4
   5 /**
   6  * Array with a maximum length 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: (T | ConcatArray<T>)[]): CircularArray<T> {
  37     const concatenatedCircularArray = super.concat(items as T[]) as CircularArray<T>;
  38     concatenatedCircularArray.size = this.size;
  39     if (concatenatedCircularArray.length > concatenatedCircularArray.size) {
  40       concatenatedCircularArray.splice(
  41         0,
  42         concatenatedCircularArray.length - concatenatedCircularArray.size
  43       );
  44     }
  45     return concatenatedCircularArray;
  46   }
  47
  48   public splice(start: number, deleteCount?: number, ...items: T[]): T[] {
  49     let itemsRemoved: T[];
  50     if (arguments.length >= 3 && typeof deleteCount !== 'undefined') {
  51       itemsRemoved = super.splice(start, deleteCount);
  52       // FIXME: that makes the items insert not in place
  53       this.push(...items);
  54     } else if (arguments.length === 2) {
  55       itemsRemoved = super.splice(start, deleteCount);
  56     } else {
  57       itemsRemoved = super.splice(start);
  58     }
  59     return itemsRemoved;
  60   }
  61
  62   public resize(size: number): void {
  63     this.checkSize(size);
  64     if (size === 0) {
  65       this.length = 0;
  66     } else if (size < this.size) {
  67       for (let i = size; i < this.size; i++) {
  68         super.pop();
  69       }
  70     }
  71     this.size = size;
  72   }
  73
  74   public empty(): boolean {
  75     return this.length === 0;
  76   }
  77
  78   public full(): boolean {
  79     return this.length === this.size;
  80   }
  81
  82   private checkSize(size: number) {
  83     if (size < 0) {
  84       throw new RangeError('Invalid circular array size');
  85     }
  86   }
  87 }