src/circular-buffer.ts

   1 /**
   2  * Default buffer size.
   3  */
   4 export const defaultBufferSize = 2048
   5
   6 /**
   7  * Circular buffer.
   8  *
   9  * @typeParam T - Type of buffer data.
  10  * @internal
  11  */
  12 export class CircularBuffer<T> {
  13   private readIdx: number
  14   private writeIdx: number
  15   private items: Array<T | undefined>
  16   private readonly maxArrayIdx: number
  17   /* Buffer number of elements */
  18   public size: number
  19
  20   /**
  21    * @param size - Buffer size. @defaultValue defaultBufferSize
  22    * @returns CircularBuffer.
  23    */
  24   constructor (size: number = defaultBufferSize) {
  25     this.checkSize(size)
  26     this.readIdx = 0
  27     this.writeIdx = 0
  28     this.maxArrayIdx = size - 1
  29     this.size = 0
  30     this.items = new Array<T | undefined>(size)
  31   }
  32
  33   /**
  34    * Checks whether the buffer is empty.
  35    *
  36    * @returns Whether the buffer is empty.
  37    */
  38   public empty (): boolean {
  39     return this.size === 0
  40   }
  41
  42   /**
  43    * Checks whether the buffer is full.
  44    *
  45    * @returns Whether the buffer is full.
  46    */
  47   public full (): boolean {
  48     return this.size === this.items.length
  49   }
  50
  51   /**
  52    * Puts data into buffer.
  53    *
  54    * @param data - Data to put into buffer.
  55    */
  56   public put (data: T): void {
  57     this.items[this.writeIdx] = data
  58     this.writeIdx = this.writeIdx === this.maxArrayIdx ? 0 : this.writeIdx + 1
  59     if (this.size < this.items.length) {
  60       ++this.size
  61     }
  62   }
  63
  64   /**
  65    * Gets data from buffer.
  66    *
  67    * @returns Data from buffer.
  68    */
  69   public get (): T | undefined {
  70     const data = this.items[this.readIdx]
  71     if (data == null) {
  72       return
  73     }
  74     this.items[this.readIdx] = undefined
  75     this.readIdx = this.readIdx === this.maxArrayIdx ? 0 : this.readIdx + 1
  76     --this.size
  77     return data
  78   }
  79
  80   /**
  81    * Returns buffer as array.
  82    *
  83    * @returns Array of buffer data.
  84    */
  85   public toArray (): T[] {
  86     return this.items.filter(item => item != null) as T[]
  87   }
  88
  89   private checkSize (size: number): void {
  90     if (!Number.isSafeInteger(size)) {
  91       throw new TypeError(
  92         `Invalid circular buffer size: ${size} is not an integer`
  93       )
  94     }
  95     if (size < 0) {
  96       throw new RangeError(`Invalid circular buffer size: ${size} < 0`)
  97     }
  98   }
  99 }