bytes/buf/
writer.rs

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1use crate::BufMut;
2
3use std::{cmp, io};
4
5/// A `BufMut` adapter which implements `io::Write` for the inner value.
6///
7/// This struct is generally created by calling `writer()` on `BufMut`. See
8/// documentation of [`writer()`](BufMut::writer) for more
9/// details.
10#[derive(Debug)]
11pub struct Writer<B> {
12    buf: B,
13}
14
15pub fn new<B>(buf: B) -> Writer<B> {
16    Writer { buf }
17}
18
19impl<B: BufMut> Writer<B> {
20    /// Gets a reference to the underlying `BufMut`.
21    ///
22    /// It is inadvisable to directly write to the underlying `BufMut`.
23    ///
24    /// # Examples
25    ///
26    /// ```rust
27    /// use bytes::BufMut;
28    ///
29    /// let buf = Vec::with_capacity(1024).writer();
30    ///
31    /// assert_eq!(1024, buf.get_ref().capacity());
32    /// ```
33    pub fn get_ref(&self) -> &B {
34        &self.buf
35    }
36
37    /// Gets a mutable reference to the underlying `BufMut`.
38    ///
39    /// It is inadvisable to directly write to the underlying `BufMut`.
40    ///
41    /// # Examples
42    ///
43    /// ```rust
44    /// use bytes::BufMut;
45    ///
46    /// let mut buf = vec![].writer();
47    ///
48    /// buf.get_mut().reserve(1024);
49    ///
50    /// assert_eq!(1024, buf.get_ref().capacity());
51    /// ```
52    pub fn get_mut(&mut self) -> &mut B {
53        &mut self.buf
54    }
55
56    /// Consumes this `Writer`, returning the underlying value.
57    ///
58    /// # Examples
59    ///
60    /// ```rust
61    /// use bytes::BufMut;
62    /// use std::io;
63    ///
64    /// let mut buf = vec![].writer();
65    /// let mut src = &b"hello world"[..];
66    ///
67    /// io::copy(&mut src, &mut buf).unwrap();
68    ///
69    /// let buf = buf.into_inner();
70    /// assert_eq!(*buf, b"hello world"[..]);
71    /// ```
72    pub fn into_inner(self) -> B {
73        self.buf
74    }
75}
76
77impl<B: BufMut + Sized> io::Write for Writer<B> {
78    fn write(&mut self, src: &[u8]) -> io::Result<usize> {
79        let n = cmp::min(self.buf.remaining_mut(), src.len());
80
81        self.buf.put_slice(&src[..n]);
82        Ok(n)
83    }
84
85    fn flush(&mut self) -> io::Result<()> {
86        Ok(())
87    }
88}
bytes/buf/writer.rs

bytes/buf/
writer.rs
