circular-buffer.ts

circular-buffer.ts

export default class CircularBuffer<T> {
  
  readonly #capacity: number
  readonly #values: T[]

  #size: number
  #head: number
  #tail: number

  constructor(capacity: number) {
    this.#capacity = capacity
    this.#values = []

    this.#size = 0
    this.#head = 0
    this.#tail = 0
  }

  write(value: T) {
    if (this.isFull()) {
      throw new BufferFullError()
    }

    this.#values[this.#tail] = value
    this.#size++
    this.#tail++

    if (this.shouldTailWrap()) {
      this.#tail = 0
    }
  }

  read(): T {
    if (this.isEmpty()) {
      throw new BufferEmptyError()
    }

    const v = this.#values[this.#head]
    this.#size--
    this.#head++

    if (this.shouldHeadWrap()) {
      this.#head = 0
    }

    return v
  }

  forceWrite(value: T) {
    if (!this.isFull()) {
      this.write(value)
      return
    }

    this.#values[this.#tail] = value
    this.#head++
    this.#tail++

    if (this.shouldHeadWrap()) {
      this.#head = 0
    }

    if (this.shouldTailWrap()) {
      this.#tail = 0
    }
  }

  clear() {
    this.#size = 0
    this.#head = 0
    this.#tail = 0
  }

  private shouldHeadWrap(): boolean {
    return this.#head == this.#capacity
  }

  private shouldTailWrap(): boolean {
    return this.#tail == this.#capacity
  }

  private isEmpty(): boolean {
    return this.#size == 0
  }

  private isFull(): boolean {
    return this.#size == this.#capacity
  }
}

export class BufferFullError extends Error {
  constructor() {
    super()
  }
}

export class BufferEmptyError extends Error {
  constructor() {
    super()
  }
}