github.com/wangkuiyi/compress_io

Compress IO

Go standard libraries support reading/writing Gzip and Bzip2 data streams. However they do not have common interface. For example, compress/bzip2.NewReader returns io.Reader, where as compress/gzip.NewReader returns io.ReadCloser. This package encapsulates the compress package and provide unified interface.

Read

Read from a file while decompressing:

 f, e := os.Open(filename)
 if r := compress_io.NewReader(f, e, path.Ext(filename)); r != nil {
   defer r.Close()
   ... read from r ...
 }

If filename has extension ".bz2", r would decompress bzip2 data stream, or if it is ".gz", then r would decompress gzip data stream, otherwise, r does not invoke any decompression algorithm.

Write

Write to a file while compressing:

  f, e := os.Create(filename)
  if w := compress_io.NewWriter(f, e, path.Ext(filename)); w != nil {
    defer w.Close()
    ... write to w ...
  }

If filename has extension ".bz2", w would compress bzip2 data stream, or if it is ".gz", then r would compress gzip data stream, otherwise, r does not invoke any compression algorithm.

Caveat

Unfortunately, Go does not support taking multiple return values as parameters, as described in this discussion. This prevents us from writing:

if w := compress_io.NewCompressWriter(os.Create(filename), path.Ext(filename))

Instead, we have to write two lines:

f, e := os.Create(filename)
w := compress_io.NewWriter(f, e, path.Ext(filename))

So, there is a possibility to write:

defer f.Close()

instead of

defer w.Close()

However, defer w.Close() is what we want.