Merge pull request #36 from cmasone-attic/stdout

Add StdoutChunkSink, a ChunkSink backed by stdout

clients/go/stdout_writer.go

@@ -0,0 +1,47 @@
+package util
+
+import (
+	"hash"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"github.com/attic-labs/noms/chunks"
+	"github.com/attic-labs/noms/dbg"
+	"github.com/attic-labs/noms/ref"
+)
+
+// StdoutChunkSink implements chunks.ChunkSink by writing data to stdout.
+type StdoutChunkSink struct {
+	chunks.ChunkSink
+}
+
+// Put returns an implementation of chunks.ChunkWriter backed by stdout.
+func (f StdoutChunkSink) Put() chunks.ChunkWriter {
+	h := ref.NewHash()
+	// Note that we never want to close stdout, so we put a NopCloser into
+	// stdoutChunkWriter to satisfy the Closer part of the ChunkWriter interface.
+	return &stdoutChunkWriter{
+		ioutil.NopCloser(nil),
+		os.Stdout,
+		io.MultiWriter(os.Stdout, h),
+		h,
+	}
+}
+
+type stdoutChunkWriter struct {
+	io.Closer
+	file   *os.File
+	writer io.Writer
+	hash   hash.Hash
+}
+
+func (w *stdoutChunkWriter) Write(data []byte) (int, error) {
+	dbg.Chk.NotNil(w.file, "Write() cannot be called after Ref() or Close().")
+	return w.writer.Write(data)
+}
+
+func (w *stdoutChunkWriter) Ref() (ref.Ref, error) {
+	w.file = nil
+	return ref.FromHash(w.hash), nil
+}