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 readonly items: Float32Array
  12   private readonly maxArrayIdx: number
  13   private readIdx: number
  14   private writeIdx: 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 the buffer size.
  32    * @param size - Buffer size.
  33    */
  34   private checkSize (size: number): void {
  35     if (!Number.isSafeInteger(size)) {
  36       throw new TypeError(
  37         `Invalid circular buffer size: '${size.toString()}' is not an integer`
  38       )
  39     }
  40     if (size < 0) {
  41       throw new RangeError(
  42         `Invalid circular buffer size: ${size.toString()} < 0`
  43       )
  44     }
  45   }
  46
  47   /**
  48    * Checks whether the buffer is empty.
  49    * @returns Whether the buffer is empty.
  50    */
  51   public empty (): boolean {
  52     return this.size === 0
  53   }
  54
  55   /**
  56    * Checks whether the buffer is full.
  57    * @returns Whether the buffer is full.
  58    */
  59   public full (): boolean {
  60     return this.size === this.items.length
  61   }
  62
  63   /**
  64    * Gets number from buffer.
  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    * Puts number into buffer.
  80    * @param number - Number to put into buffer.
  81    */
  82   public put (number: number): void {
  83     this.items[this.writeIdx] = number
  84     this.writeIdx = this.writeIdx === this.maxArrayIdx ? 0 : this.writeIdx + 1
  85     if (this.size < this.items.length) {
  86       ++this.size
  87     }
  88   }
  89
  90   /**
  91    * Returns buffer as numbers' array.
  92    * @returns Numbers' array.
  93    */
  94   public toArray (): number[] {
  95     return Array.from(this.items.filter(item => item !== -1))
  96   }
  97 }