messagepack_core/
io.rs

1pub trait IoWrite {
2    type Error: core::error::Error;
3    fn write_byte(&mut self, byte: u8) -> Result<(), Self::Error>;
4    fn write_bytes(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
5        for byte in buf {
6            self.write_byte(*byte)?;
7        }
8
9        Ok(())
10    }
11}
12
13/// `SliceWriter` Error
14#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
15pub enum WError {
16    /// buffer is full
17    BufferFull,
18}
19
20impl core::fmt::Display for WError {
21    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
22        match self {
23            WError::BufferFull => write!(f, "Buffer is full"),
24        }
25    }
26}
27
28impl core::error::Error for WError {}
29
30pub struct SliceWriter<'a> {
31    buf: &'a mut [u8],
32    cursor: usize,
33}
34
35impl<'a> SliceWriter<'a> {
36    pub fn from_slice(buf: &'a mut [u8]) -> Self {
37        Self { buf, cursor: 0 }
38    }
39
40    fn len(&self) -> usize {
41        self.buf.len() - self.cursor
42    }
43}
44
45impl IoWrite for SliceWriter<'_> {
46    type Error = WError;
47
48    fn write_byte(&mut self, byte: u8) -> Result<(), Self::Error> {
49        if self.len() >= 1 {
50            self.buf[self.cursor] = byte;
51            self.cursor += 1;
52            Ok(())
53        } else {
54            Err(WError::BufferFull)
55        }
56    }
57
58    fn write_bytes(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
59        if self.len() >= buf.len() {
60            let to = &mut self.buf[self.cursor..self.cursor + buf.len()];
61            to.copy_from_slice(buf);
62            self.cursor += buf.len();
63            Ok(())
64        } else {
65            Err(WError::BufferFull)
66        }
67    }
68}
69
70#[cfg(any(test, feature = "std"))]
71impl<W> IoWrite for W
72where
73    W: std::io::Write,
74{
75    type Error = std::io::Error;
76
77    fn write_byte(&mut self, byte: u8) -> Result<(), Self::Error> {
78        match self.write_all(&[byte]) {
79            Ok(_) => Ok(()),
80            Err(e) => Err(e),
81        }
82    }
83}
84
85#[cfg(test)]
86mod tests {
87    use super::*;
88
89    #[test]
90    #[should_panic]
91    fn buffer_full() {
92        let buf: &mut [u8] = &mut [0u8];
93        let mut writer = SliceWriter::from_slice(buf);
94        writer.write_bytes(&[1, 2]).unwrap();
95    }
96}
messagepack_core/io.rs

messagepack_core/
io.rs
