Function createZlibTransformObject

samples/14-compression.ts:256–355

* Generic factory for creating zlib transform objects.

(
  createZlib: () => zlib.Gzip | zlib.Gunzip | zlib.Deflate | zlib.Inflate | zlib.BrotliCompress | zlib.BrotliDecompress
)

 * Generic factory for creating zlib transform objects.
 */
function createZlibTransformObject(
  createZlib: () => zlib.Gzip | zlib.Gunzip | zlib.Deflate | zlib.Inflate | zlib.BrotliCompress | zlib.BrotliDecompress
): TransformObject {
  const zlibStream = createZlib();
  const pending: Uint8Array[] = [];
  let error: Error | null = null;
  let pendingReject: ((err: Error) => void) | null = null;

  zlibStream.on('data', (chunk: Buffer) => {
    pending.push(new Uint8Array(chunk));
  });

  zlibStream.on('error', (err) => {
    error = err;
    // Immediately reject any pending operation
    if (pendingReject) {
      pendingReject(err);
      pendingReject = null;
    }
  });

  async function processChunk(chunk: Uint8Array | null): Promise<Uint8Array[]> {
    return new Promise((resolve, reject) => {
      if (error) {
        reject(error);
        return;
      }

      // Store reject for async error handling
      pendingReject = reject;

      if (chunk === null) {
        // Use 'end' event (not 'finish') because 'end' fires AFTER final data is emitted
        zlibStream.once('end', () => {
          pendingReject = null;
          if (error) {
            reject(error);
          } else {
            resolve(pending.splice(0));
          }
        });
        zlibStream.end();
        return;
      }

      // Write and flush to get all output
      zlibStream.write(copyToBuffer(chunk), (err) => {
        if (err) {
          pendingReject = null;
          reject(err);
          return;
        }
        if (error) {
          pendingReject = null;
          reject(error);
          return;
        }
        zlibStream.flush(() => {