2008-11-25 10:41:58 -07:00
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package io
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// Byte buffer for marshaling nested messages.
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import (
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"io";
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"os";
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)
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// A simple implementation of the io.Read and io.Write interfaces.
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// A newly allocated ByteBuffer is ready to use.
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// TODO(r): Do better memory management.
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func bytecopy(dst *[]byte, doff int, src *[]byte, soff int, count int) {
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for i := 0; i < count; i++ {
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dst[doff] = src[soff];
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doff++;
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soff++;
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}
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}
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export type ByteBuffer struct {
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buf *[]byte;
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off int; // Read from here
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len int; // Write to here
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cap int;
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}
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func (b *ByteBuffer) Reset() {
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b.off = 0;
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b.len = 0;
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}
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func (b *ByteBuffer) Write(p *[]byte) (n int, err *os.Error) {
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plen := len(p);
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if b.buf == nil {
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b.cap = plen + 1024;
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b.buf = new([]byte, b.cap);
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b.len = 0;
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}
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if b.len + len(p) > b.cap {
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b.cap = 2*(b.cap + plen);
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nb := new([]byte, b.cap);
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bytecopy(nb, 0, b.buf, 0, b.len);
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b.buf = nb;
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}
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bytecopy(b.buf, b.len, p, 0, plen);
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b.len += plen;
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return plen, nil;
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}
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func (b *ByteBuffer) Read(p *[]byte) (n int, err *os.Error) {
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plen := len(p);
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if b.buf == nil {
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return 0, nil
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}
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if b.off == b.len { // empty buffer
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b.Reset();
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return 0, nil
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}
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if plen > b.len - b.off {
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plen = b.len - b.off
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}
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bytecopy(p, 0, b.buf, b.off, plen);
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b.off += plen;
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return plen, nil;
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}
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func (b *ByteBuffer) Len() int {
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return b.len
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}
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2008-12-16 14:01:39 -07:00
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// If the buffer is empty, Data() should still give a valid array.
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// Use this variable as a surrogate. It's immutable (can't be
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// grown, can't store any data) so it's safe to share.
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var EmptyByteArray = new([]byte, 0)
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2008-11-25 10:41:58 -07:00
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func (b *ByteBuffer) Data() *[]byte {
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2008-12-16 14:01:39 -07:00
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if b.buf == nil {
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return EmptyByteArray
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}
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2008-11-25 10:41:58 -07:00
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return b.buf[b.off:b.len]
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}
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export func NewByteBufferFromArray(buf *[]byte) *ByteBuffer {
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b := new(ByteBuffer);
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b.buf = buf;
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b.off = 0;
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b.len = len(buf);
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b.cap = len(buf);
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return b;
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}
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