Function createMessageBuffer

npm_modules/cli/test/helpers/TypeScriptClient.ts:159–203

* Create a statefull message buffer that parses TSServer messages. * * @returns {(chunk: Buffer) => Generator<[body: Record , headers: Array<[name: string, value: string]>]>}

()

 * @returns {(chunk: Buffer) => Generator<[body: Record<string, unknown>, headers: Array<[name: string, value: string]>]>}
 */
function createMessageBuffer(): (
  chunk: Buffer,
) => Generator<[body: Record<string, unknown>, headers: Array<[name: string, value: string]>]> {
  let buffer = Buffer.from([]);
  /**
   *
   * @param {Buffer} chunk
   * @return {Generator<[body: Record<string, unknown>, headers: Array<[name: string, value: string]>]>}
   */
  return function* read(chunk) {
    buffer = Buffer.concat([buffer, chunk]);

    let position = 0;

    while (position < buffer.length) {
      const headerSuffix = buffer.indexOf(HEADER_END, position);

      if (headerSuffix === -1) {
        throw new Error('no headers ' + buffer.toString('utf8'));
      }

      const headers: [string, string][] = Array.from(parseHeaders(buffer.subarray(position, headerSuffix)));

      // Content length
      const contentLength = Number.parseInt(
        headers.find(([name]) => name === 'Content-Length')?.[1] ?? Number.NaN.toString(),
      );
      if (Number.isNaN(contentLength)) {
        throw new TypeError('invalid message, no Content-Length');
      }

      const bodyStart = headerSuffix + HEADER_END.length;
      const bodyEnd = bodyStart + contentLength;

      if (bodyEnd > buffer.length) {
        buffer = buffer.subarray(position);
        return;
      }

      yield [JSON.parse(buffer.subarray(bodyStart, bodyEnd).toString('utf8')), headers];

      position = bodyEnd;
    }
  };
}

/**
 * Every time the returned function is called it will return a new sequenc.