ringbuffer.ts

export default class RingBuffer<T> {
  _max_length: number;
  _buffer: T[];
  _write_head: number;
  _length: number;

  constructor(max_length: number) {
    this._max_length = max_length;
    this._buffer = new Array(max_length);
    this._write_head = 0;
    this._length = 0;
  }

  add(...values: T[]) {
    values.forEach(value => {
      this._buffer[this._write_head] = value;
      this._write_head = (this._write_head + 1) % this._max_length;
      this._length = Math.min(this._length + 1, this._max_length);
    });
  }

  get_all(): T[] {
    let start = this._write_head;
    let first_slice = this._buffer.slice(start, this._length);
    let second_slice = this._buffer.slice(0, start);
    return first_slice.concat(second_slice);
  }

  get_last(count: number): T[] {
    return this.get_all().slice(-count);
  }
}