src/utils/CircularArray.ts

   1 export const DEFAULT_CIRCULAR_ARRAY_SIZE = 2000;
   2
   3 /** Array with a maximum length shifting items when full. */
   4 export class CircularArray<T> extends Array<T> {
   5   public size: number;
   6
   7   constructor(size: number = DEFAULT_CIRCULAR_ARRAY_SIZE, ...items: T[]) {
   8     super();
   9     this.checkSize(size);
  10     this.size = size;
  11     if (arguments.length > 1) {
  12       this.push(...items);
  13     }
  14   }
  15
  16   public push(...items: T[]): number {
  17     const length = super.push(...items);
  18     if (length > this.size) {
  19       super.splice(0, length - this.size);
  20     }
  21     return this.length;
  22   }
  23
  24   public unshift(...items: T[]): number {
  25     const length = super.unshift(...items);
  26     if (length > this.size) {
  27       super.splice(this.size, items.length);
  28     }
  29     return this.length;
  30   }
  31
  32   public concat(...items: (T | ConcatArray<T>)[]): CircularArray<T> {
  33     const concatenatedCircularArray = super.concat(
  34       items as T[]
  35     ) 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 }