12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061
import { concatUint8Array, readInt32BE } from "./util.ts";
interface Options {  headerSize?: number;  lengthSize?: number;}
export default class Reader {  #header!: string;  #length!: number;  private offset = 0;  private chunk: Uint8Array;  private chunkLength: number = 0;  private headerSize: number;  private lengthSize: number;  private decoder = new TextDecoder();
  constructor(chunk: Uint8Array, options?: Options) {    this.chunk = chunk;    this.chunkLength = chunk.byteLength;    this.headerSize = options?.headerSize ?? 1;    this.lengthSize = options?.lengthSize ?? 4;  }
  get header() {    return this.#header;  }
  get length() {    return this.#length;  }
  addChunk(chunk: Uint8Array) {    this.chunk = concatUint8Array([this.chunk, chunk]);    this.chunkLength += chunk.byteLength;  }
  read(): Uint8Array | null {    if (      this.chunkLength < this.headerSize + this.lengthSize + this.offset    ) {      return null;    }
    this.#header = this.decoder.decode(      this.chunk.subarray(this.offset, this.offset += this.headerSize),    );    this.#length = readInt32BE(this.chunk, this.offset);    const remaining = this.chunkLength - this.offset;    if (this.#length > remaining) return null;
    const result = this.chunk.subarray(      this.offset + this.lengthSize,      this.offset + this.#length,    );    this.offset += this.#length;
    return result;  }}