var flateWriterPool sync.Pool

func newFlateWriter(w io.Writer) io.WriteCloser {
	fw, ok := flateWriterPool.Get().(*flate.Writer)
	if ok {
		fw.Reset(w)
	} else {
		fw, _ = flate.NewWriter(w, 5)
	}
	return &pooledFlateWriter{fw: fw}
}

type pooledFlateWriter struct {
	mu sync.Mutex // guards Close and Write
	fw *flate.Writer
}

func (w *pooledFlateWriter) Write(p []byte) (n int, err error) {
	w.mu.Lock()

	// Create a new zip archive.
	w := zip.NewWriter(buf)

	// Register a custom Deflate compressor.
	w.RegisterCompressor(zip.Deflate, func(out io.Writer) (io.WriteCloser, error) {
		return flate.NewWriter(out, flate.BestCompression)
	})

	// Proceed to add files to w.

		// Lookup remainder of path in each array element and
		// make result array.
		var result []interface{}
		for _, a := range arr {
			rval, flatten, err := jsonpathEval(p[1:], a)
			if err != nil {
				return nil, false, err
			}

			if flatten {
				// Flatten if array.
				if arr, ok := rval.([]interface{}); ok {
					result = append(result, arr...)
					continue
				}
			}