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 /** Array with a maximum length shifting items when full. */
   6 export class CircularArray<T> extends Array<T> {
   7   public size: number;
   8
   9   constructor(size: number = DEFAULT_CIRCULAR_ARRAY_SIZE, ...items: T[]) {
  10     super();
  11     this.checkSize(size);
  12     this.size = size;
  13     if (arguments.length > 1) {
  14       this.push(...items);
  15     }
  16   }
  17
  18   public push(...items: T[]): number {
  19     const length = super.push(...items);
  20     if (length > this.size) {
  21       super.splice(0, length - this.size);
  22     }
  23     return this.length;
  24   }
  25
  26   public unshift(...items: T[]): number {
  27     const length = super.unshift(...items);
  28     if (length > this.size) {
  29       super.splice(this.size, items.length);
  30     }
  31     return this.length;
  32   }
  33
  34   public concat(...items: (T | ConcatArray<T>)[]): CircularArray<T> {
  35     const concatenatedCircularArray = super.concat(items as T[]) as CircularArray<T>;
  36     concatenatedCircularArray.size = this.size;
  37     if (concatenatedCircularArray.length > concatenatedCircularArray.size) {
  38       concatenatedCircularArray.splice(
  39         0,
  40         concatenatedCircularArray.length - concatenatedCircularArray.size
  41       );
  42     }
  43     return concatenatedCircularArray;
  44   }
  45
  46   public splice(start: number, deleteCount?: number, ...items: T[]): T[] {
  47     let itemsRemoved: T[];
  48     if (arguments.length >= 3 && typeof deleteCount !== 'undefined') {
  49       itemsRemoved = super.splice(start, deleteCount);
  50       // FIXME: that makes the items insert not in place
  51       this.push(...items);
  52     } else if (arguments.length === 2) {
  53       itemsRemoved = super.splice(start, deleteCount);
  54     } else {
  55       itemsRemoved = super.splice(start);
  56     }
  57     return itemsRemoved;
  58   }
  59
  60   public resize(size: number): void {
  61     this.checkSize(size);
  62     if (size === 0) {
  63       this.length = 0;
  64     } else if (size < this.size) {
  65       for (let i = size; i < this.size; i++) {
  66         super.pop();
  67       }
  68     }
  69     this.size = size;
  70   }
  71
  72   public empty(): boolean {
  73     return this.length === 0;
  74   }
  75
  76   public full(): boolean {
  77     return this.length === this.size;
  78   }
  79
  80   private checkSize(size: number) {
  81     if (size < 0) {
  82       throw new RangeError('Invalid circular array size');
  83     }
  84   }
  85 }