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