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
diff --git a/src/lib/io/bytebuffer.go b/src/lib/io/bytebuffer.go
new file mode 100644
index 0000000..9035367
--- /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;
+}
