rc_u8_reader/
rc_u8_reader.rs

1use std::cmp;
2use std::fmt::{self, Debug, Formatter};
3use std::io::{self, BufRead, ErrorKind, Read, Seek, SeekFrom};
4use std::rc::Rc;
5
6pub struct RcU8Reader<T: AsRef<[u8]> + ?Sized> {
7    data: Rc<T>,
8    pos: usize,
9}
10
11impl<T: AsRef<[u8]> + ?Sized> Debug for RcU8Reader<T> {
12    #[inline]
13    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
14        debug_helper::impl_debug_for_struct!(RcU8Reader, f, self, let .data = self.data.as_ref().as_ref(), .pos);
15    }
16}
17
18impl<T: AsRef<[u8]> + ?Sized> RcU8Reader<T> {
19    #[inline]
20    pub fn new(data: Rc<T>) -> RcU8Reader<T> {
21        RcU8Reader {
22            data,
23            pos: 0,
24        }
25    }
26}
27
28impl<T: AsRef<[u8]> + ?Sized> BufRead for RcU8Reader<T> {
29    #[inline]
30    fn fill_buf(&mut self) -> Result<&[u8], io::Error> {
31        let data = (*self.data).as_ref();
32
33        let amt = cmp::min(self.pos, data.len());
34
35        Ok(&data[amt..])
36    }
37
38    #[inline]
39    fn consume(&mut self, amt: usize) {
40        self.pos += amt;
41    }
42}
43
44impl<T: AsRef<[u8]> + ?Sized> Read for RcU8Reader<T> {
45    #[inline]
46    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
47        let n = Read::read(&mut self.fill_buf()?, buf)?;
48
49        self.pos += n;
50
51        Ok(n)
52    }
53
54    #[inline]
55    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
56        let n = buf.len();
57
58        Read::read_exact(&mut self.fill_buf()?, buf)?;
59
60        self.pos += n;
61
62        Ok(())
63    }
64}
65
66impl<T: AsRef<[u8]> + ?Sized> Seek for RcU8Reader<T> {
67    fn seek(&mut self, style: SeekFrom) -> Result<u64, io::Error> {
68        let (base_pos, offset) = match style {
69            SeekFrom::Start(n) => {
70                let n = if n > usize::MAX as u64 {
71                    usize::MAX
72                } else {
73                    n as usize
74                };
75
76                self.pos = n;
77
78                return Ok(n as u64);
79            }
80            SeekFrom::End(n) => ((*self.data).as_ref().len(), n),
81            SeekFrom::Current(n) => (self.pos, n),
82        };
83
84        let offset = if offset > isize::MAX as i64 {
85            isize::MAX
86        } else if offset < isize::MIN as i64 {
87            isize::MIN
88        } else {
89            offset as isize
90        };
91
92        let new_pos = if offset >= 0 {
93            base_pos.checked_add(offset as usize)
94        } else {
95            base_pos.checked_sub((offset.wrapping_neg()) as usize)
96        };
97
98        match new_pos {
99            Some(n) => {
100                self.pos = n;
101
102                Ok(self.pos as u64)
103            }
104            None => {
105                Err(io::Error::new(
106                    ErrorKind::InvalidInput,
107                    "invalid seek to a negative or overflowing position",
108                ))
109            }
110        }
111    }
112}
rc_u8_reader/rc_u8_reader.rs

rc_u8_reader/
rc_u8_reader.rs
