make a (rudimentary) ByteBuffer and put it in package "io".

fix up protocol buffers to use it.

R=rsc
DELTA=1232  (612 added, 572 deleted, 48 changed)
OCL=19964
CL=19981

1 files changed, 90 insertions, 0 deletions

diff --git a/src/lib/io/bytebuffer.go b/src/lib/io/bytebuffer.go
new file mode 100644
index 000000000..903536717
--- /dev/null
+++ b/src/lib/io/bytebuffer.go
@@ -0,0 +1,90 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io
+
+// Byte buffer for marshaling nested messages.
+
+import (
+	"io";
+	"os";
+)
+
+// A simple implementation of the io.Read and io.Write interfaces.
+// A newly allocated ByteBuffer is ready to use.
+
+// TODO(r): Do better memory management.
+
+func bytecopy(dst *[]byte, doff int, src *[]byte, soff int, count int) {
+	for i := 0; i < count; i++ {
+		dst[doff] = src[soff];
+		doff++;
+		soff++;
+	}
+}
+
+export type ByteBuffer struct {
+	buf	*[]byte;
+	off	int;	// Read from here
+	len	int;	// Write to here
+	cap	int;
+}
+
+func (b *ByteBuffer) Reset() {
+	b.off = 0;
+	b.len = 0;
+}
+
+func (b *ByteBuffer) Write(p *[]byte) (n int, err *os.Error) {
+	plen := len(p);
+	if b.buf == nil {
+		b.cap = plen + 1024;
+		b.buf = new([]byte, b.cap);
+		b.len = 0;
+	}
+	if b.len + len(p) > b.cap {
+		b.cap = 2*(b.cap + plen);
+		nb := new([]byte, b.cap);
+		bytecopy(nb, 0, b.buf, 0, b.len);
+		b.buf = nb;
+	}
+	bytecopy(b.buf, b.len, p, 0, plen);
+	b.len += plen;
+	return plen, nil;
+}
+
+func (b *ByteBuffer) Read(p *[]byte) (n int, err *os.Error) {
+	plen := len(p);
+	if b.buf == nil {
+		return 0, nil
+	}
+	if b.off == b.len {	// empty buffer
+		b.Reset();
+		return 0, nil
+	}
+	if plen > b.len - b.off {
+		plen = b.len - b.off
+	}
+	bytecopy(p, 0, b.buf, b.off, plen);
+	b.off += plen;
+	return plen, nil;
+}
+
+func (b *ByteBuffer) Len() int {
+	return b.len
+}
+
+func (b *ByteBuffer) Data() *[]byte {
+	return b.buf[b.off:b.len]
+}
+
+
+export func NewByteBufferFromArray(buf *[]byte) *ByteBuffer {
+	b := new(ByteBuffer);
+	b.buf = buf;
+	b.off = 0;
+	b.len = len(buf);
+	b.cap = len(buf);
+	return b;
+}