1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
// 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
// Simple byte buffer for marshaling data.
import (
"io";
"os";
)
func bytecopy(dst []byte, doff int, src []byte, soff int, count int) {
for ; count > 0; count-- {
dst[doff] = src[soff];
doff++;
soff++;
}
}
// A ByteBuffer is a simple implementation of the io.Read and io.Write interfaces
// connected to a buffer of bytes.
// The zero value for ByteBuffer is an empty buffer ready to use.
type ByteBuffer struct {
buf []byte; // contents are the bytes buf[off : len(buf)]
off int; // read at &buf[off], write at &buf[len(buf)]
}
// Data returns the contents of the unread portion of the buffer;
// len(b.Data()) == b.Len().
func (b *ByteBuffer) Data() []byte {
return b.buf[b.off : len(b.buf)]
}
// Len returns the number of bytes of the unread portion of the buffer;
// b.Len() == len(b.Data()).
func (b *ByteBuffer) Len() int {
return len(b.buf) - b.off
}
// Truncate discards all but the first n unread bytes from the buffer.
// It is an error to call b.Truncate(n) with n > b.Len().
func (b *ByteBuffer) Truncate(n int) {
if n == 0 {
// Reuse buffer space.
b.off = 0;
}
b.buf = b.buf[0 : b.off + n];
}
// Reset resets the buffer so it has no content.
// b.Reset() is the same as b.Truncate(0).
func (b *ByteBuffer) Reset() {
b.Truncate(0);
}
// Write appends the contents of p to the buffer. The return
// value n is the length of p; err is always nil.
func (b *ByteBuffer) Write(p []byte) (n int, err os.Error) {
m := b.Len();
n = len(p);
if len(b.buf) + n > cap(b.buf) {
// not enough space at end
buf := b.buf;
if m + n > cap(b.buf) {
// not enough space anywhere
buf = make([]byte, 2*cap(b.buf) + n)
}
bytecopy(buf, 0, b.buf, b.off, m);
b.buf = buf;
b.off = 0
}
b.buf = b.buf[0 : b.off + m + n];
bytecopy(b.buf, b.off + m, p, 0, n);
return n, nil
}
// WriteByte appends the byte c to the buffer.
// The returned error is always nil, but is included
// to match bufio.Writer's WriteByte.
func (b *ByteBuffer) WriteByte(c byte) os.Error {
b.Write([]byte{c});
return nil;
}
// Read reads the next len(p) bytes from the buffer or until the buffer
// is drained. The return value n is the number of bytes read; err is always nil.
func (b *ByteBuffer) Read(p []byte) (n int, err os.Error) {
m := b.Len();
n = len(p);
if n > m {
// more bytes requested than available
n = m
}
bytecopy(p, 0, b.buf, b.off, n);
b.off += n;
return n, nil
}
// NewByteBufferFromArray creates and initializes a new ByteBuffer
// with buf as its initial contents.
func NewByteBufferFromArray(buf []byte) *ByteBuffer {
return &ByteBuffer{buf, 0};
}
|
