MutableBuffer.ts

// Experimental `push(...bytes)`-able buffer
// Unfortunately, it is always slower than Array<number>.

export class MutableBuffer {
  private length = 0;
  private buffer = new Uint8Array(32);

  push(...bytes: ReadonlyArray<number>): void {
    const newLength = this.length + bytes.length;

    if (this.buffer.length < newLength) {
      this.grow(newLength);
    }

    this.buffer.set(bytes, this.length);
    this.length = newLength;
  }

  grow(newLength: number) {
    const newBuffer = new Uint8Array(newLength * 2);
    newBuffer.set(this.buffer);
    this.buffer = newBuffer;
  }

  toUint8Array(): Uint8Array {
    return this.buffer.slice(0, this.length);
  }

  toArray(): Array<number> {
    return Array.from(this.toUint8Array());
  }
}