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