embedded_io/impls/
vec_deque.rs

1//! Adapted from std.
2
3use core::convert::Infallible;
4
5use alloc::collections::vec_deque::VecDeque;
6
7use crate::{BufRead, ErrorType, Read, ReadExactError, ReadReady, Write, WriteReady};
8
9#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
10impl ErrorType for VecDeque<u8> {
11    type Error = Infallible;
12}
13
14/// Read is implemented for `VecDeque<u8>` by consuming bytes from the front of the `VecDeque`.
15#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
16impl Read for VecDeque<u8> {
17    /// Fill `buf` with the contents of the "front" slice as returned by
18    /// [`as_slices`][`VecDeque::as_slices`]. If the contained byte slices of the `VecDeque` are
19    /// discontiguous, multiple calls to `read` will be needed to read the entire content.
20    #[inline]
21    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
22        let (ref mut front, _) = self.as_slices();
23        let n = Read::read(front, buf)?;
24        self.drain(..n);
25        Ok(n)
26    }
27
28    #[inline]
29    fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), ReadExactError<Self::Error>> {
30        let (front, back) = self.as_slices();
31
32        // Use only the front buffer if it is big enough to fill `buf`, else use
33        // the back buffer too.
34        match buf.split_at_mut_checked(front.len()) {
35            None => buf.copy_from_slice(&front[..buf.len()]),
36            Some((buf_front, buf_back)) => match back.split_at_checked(buf_back.len()) {
37                Some((back, _)) => {
38                    buf_front.copy_from_slice(front);
39                    buf_back.copy_from_slice(back);
40                }
41                None => {
42                    self.clear();
43                    return Err(ReadExactError::UnexpectedEof);
44                }
45            },
46        }
47
48        self.drain(..buf.len());
49        Ok(())
50    }
51}
52
53/// BufRead is implemented for `VecDeque<u8>` by reading bytes from the front of the `VecDeque`.
54#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
55impl BufRead for VecDeque<u8> {
56    /// Returns the contents of the "front" slice as returned by
57    /// [`as_slices`][`VecDeque::as_slices`]. If the contained byte slices of the `VecDeque` are
58    /// discontiguous, multiple calls to `fill_buf` will be needed to read the entire content.
59    #[inline]
60    fn fill_buf(&mut self) -> Result<&[u8], Self::Error> {
61        let (front, _) = self.as_slices();
62        Ok(front)
63    }
64
65    #[inline]
66    fn consume(&mut self, amt: usize) {
67        self.drain(..amt);
68    }
69}
70
71/// Write is implemented for `VecDeque<u8>` by appending to the `VecDeque`, growing it as needed.
72#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
73impl Write for VecDeque<u8> {
74    #[inline]
75    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
76        self.extend(buf);
77        Ok(buf.len())
78    }
79
80    #[inline]
81    fn write_all(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
82        self.extend(buf);
83        Ok(())
84    }
85
86    #[inline]
87    fn flush(&mut self) -> Result<(), Self::Error> {
88        Ok(())
89    }
90}
91
92#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
93impl ReadReady for VecDeque<u8> {
94    #[inline]
95    fn read_ready(&mut self) -> Result<bool, Self::Error> {
96        Ok(true)
97    }
98}
99
100#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
101impl WriteReady for VecDeque<u8> {
102    #[inline]
103    fn write_ready(&mut self) -> Result<bool, Self::Error> {
104        Ok(true)
105    }
106}
embedded_io/impls/vec_deque.rs

embedded_io/impls/
vec_deque.rs
