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
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
use std::io;
use std::io::{Read, Seek, SeekFrom, Write};
use super::{ReadAt, Size, WriteAt};
#[derive(Debug, Clone)]
pub struct Cursor<I> {
io: I,
pos: u64,
}
impl<I> Cursor<I> {
#[inline]
pub fn new_pos(io: I, pos: u64) -> Self {
Cursor { io, pos }
}
#[inline]
pub fn new(io: I) -> Self {
Self::new_pos(io, 0)
}
#[inline]
pub fn into_inner(self) -> I {
self.io
}
#[inline]
pub fn get_ref(&self) -> &I {
&self.io
}
#[inline]
pub fn get_mut(&mut self) -> &mut I {
&mut self.io
}
#[inline]
pub fn position(&self) -> u64 {
self.pos
}
#[inline]
pub fn set_position(&mut self, pos: u64) {
self.pos = pos;
}
}
impl<I> Seek for Cursor<I> {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
match pos {
SeekFrom::Start(p) => self.pos = p,
SeekFrom::Current(p) => {
let pos = self.pos as i64 + p;
if pos < 0 {
return Err(io::Error::new(io::ErrorKind::InvalidInput, "seek to a negative position"));
}
self.pos = pos as u64;
}
SeekFrom::End(_) => {
return Err(io::Error::new(io::ErrorKind::InvalidInput, "seek from unknown end"))
}
}
Ok(self.pos)
}
}
impl<I: ReadAt> Read for Cursor<I> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let bytes = self.get_ref().read_at(self.pos, buf)?;
self.pos += bytes as u64;
Ok(bytes)
}
}
impl<I: WriteAt> Write for Cursor<I> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let pos = self.pos;
let bytes = self.get_mut().write_at(pos, buf)?;
self.pos += bytes as u64;
Ok(bytes)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
WriteAt::flush(self.get_mut())
}
}
#[derive(Debug, Clone)]
pub struct SizeCursor<I: Size> {
cursor: Cursor<I>,
}
impl<I: Size> SizeCursor<I> {
#[inline]
pub fn new_pos(io: I, pos: u64) -> Self {
SizeCursor {
cursor: Cursor::new_pos(io, pos)
}
}
#[inline]
pub fn new(io: I) -> Self {
SizeCursor {
cursor: Cursor::new(io)
}
}
#[inline]
pub fn as_cursor(&self) -> &Cursor<I> {
&self.cursor
}
#[inline]
pub fn as_cursor_mut(&mut self) -> &mut Cursor<I> {
&mut self.cursor
}
#[inline]
pub fn into_cursor(self) -> Cursor<I> {
self.cursor
}
#[inline]
pub fn into_inner(self) -> I {
self.cursor.io
}
#[inline]
pub fn get_ref(&self) -> &I {
&self.cursor.io
}
#[inline]
pub fn get_mut(&mut self) -> &mut I {
&mut self.cursor.io
}
#[inline]
pub fn position(&self) -> u64 {
self.cursor.position()
}
#[inline]
pub fn set_position(&mut self, pos: u64) {
self.cursor.set_position(pos)
}
}
impl<I: Size + ReadAt> Read for SizeCursor<I> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.cursor.read(buf)
}
}
impl<I: Size + WriteAt> Write for SizeCursor<I> {
#[inline]
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.cursor.write(buf)
}
#[inline]
fn flush(&mut self) -> io::Result<()> {
self.cursor.flush()
}
}
impl<I: Size> Seek for SizeCursor<I> {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
let pos = match pos {
SeekFrom::Start(p) => p as i64,
SeekFrom::Current(p) => self.cursor.pos as i64 + p,
SeekFrom::End(p) => {
match self.get_ref().size() {
Err(e) => return Err(e),
Ok(None) => {
return Err(io::Error::new(io::ErrorKind::InvalidData, "seek from unknown end"))
}
Ok(Some(s)) => s as i64 + p,
}
}
};
self.cursor.pos = pos as u64;
Ok(self.cursor.pos)
}
}