src/circular-buffer.ts

   1 /**
   2  * Default buffer size.
   3  */
   4 export const defaultBufferSize = 2048
   5
   6 /**
   7  * Circular buffer designed for positive numbers.
   8  *
   9  * @internal
  10  */
  11 export class CircularBuffer {
  12   private readIdx: number
  13   private writeIdx: number
  14   private items: Float32Array
  15   private readonly maxArrayIdx: number
  16   public size: number
  17
  18   /**
  19    * @param size - Buffer size. @defaultValue defaultBufferSize
  20    * @returns CircularBuffer.
  21    */
  22   constructor (size: number = defaultBufferSize) {
  23     this.checkSize(size)
  24     this.readIdx = 0
  25     this.writeIdx = 0
  26     this.maxArrayIdx = size - 1
  27     this.size = 0
  28     this.items = new Float32Array(size).fill(-1)
  29   }
  30
  31   /**
  32    * Checks whether the buffer is empty.
  33    *
  34    * @returns Whether the buffer is empty.
  35    */
  36   public empty (): boolean {
  37     return this.size === 0
  38   }
  39
  40   /**
  41    * Checks whether the buffer is full.
  42    *
  43    * @returns Whether the buffer is full.
  44    */
  45   public full (): boolean {
  46     return this.size === this.items.length
  47   }
  48
  49   /**
  50    * Puts number into buffer.
  51    *
  52    * @param number - Number to put into buffer.
  53    */
  54   public put (number: number): void {
  55     this.items[this.writeIdx] = number
  56     this.writeIdx = this.writeIdx === this.maxArrayIdx ? 0 : this.writeIdx + 1
  57     if (this.size < this.items.length) {
  58       ++this.size
  59     }
  60   }
  61
  62   /**
  63    * Gets number from buffer.
  64    *
  65    * @returns Number from buffer.
  66    */
  67   public get (): number | undefined {
  68     const number = this.items[this.readIdx]
  69     if (number === -1) {
  70       return
  71     }
  72     this.items[this.readIdx] = -1
  73     this.readIdx = this.readIdx === this.maxArrayIdx ? 0 : this.readIdx + 1
  74     --this.size
  75     return number
  76   }
  77
  78   /**
  79    * Returns buffer as numbers' array.
  80    *
  81    * @returns Numbers' array.
  82    */
  83   public toArray (): number[] {
  84     return Array.from(this.items.filter(item => item !== -1))
  85   }
  86
  87   private checkSize (size: number): void {
  88     if (!Number.isSafeInteger(size)) {
  89       throw new TypeError(
  90         `Invalid circular buffer size: ${size} is not an integer`
  91       )
  92     }
  93     if (size < 0) {
  94       throw new RangeError(`Invalid circular buffer size: ${size} < 0`)
  95     }
  96   }
  97 }