fluke_maybe_uring/buf/
slice.rs

1use crate::buf::{IoBuf, IoBufMut};
2
3use std::cmp;
4use std::ops;
5
6/// An owned view into a contiguous sequence of bytes.
7///
8/// This is similar to Rust slices (`&buf[..]`) but owns the underlying buffer.
9/// This type is useful for performing io-uring read and write operations using
10/// a subset of a buffer.
11///
12/// Slices are created using [`IoBuf::slice`].
13///
14/// # Examples
15///
16/// Creating a slice
17///
18/// ```
19/// use tokio_uring::buf::IoBuf;
20///
21/// let buf = b"hello world".to_vec();
22/// let slice = buf.slice(..5);
23///
24/// assert_eq!(&slice[..], b"hello");
25/// ```
26pub struct Slice<T> {
27    buf: T,
28    begin: usize,
29    end: usize,
30}
31
32impl<T> Slice<T> {
33    pub(crate) fn new(buf: T, begin: usize, end: usize) -> Slice<T> {
34        Slice { buf, begin, end }
35    }
36
37    /// Offset in the underlying buffer at which this slice starts.
38    ///
39    /// # Examples
40    ///
41    /// ```
42    /// use tokio_uring::buf::IoBuf;
43    ///
44    /// let buf = b"hello world".to_vec();
45    /// let slice = buf.slice(1..5);
46    ///
47    /// assert_eq!(1, slice.begin());
48    /// ```
49    pub fn begin(&self) -> usize {
50        self.begin
51    }
52
53    /// Ofset in the underlying buffer at which this slice ends.
54    ///
55    /// # Examples
56    ///
57    /// ```
58    /// use tokio_uring::buf::IoBuf;
59    ///
60    /// let buf = b"hello world".to_vec();
61    /// let slice = buf.slice(1..5);
62    ///
63    /// assert_eq!(5, slice.end());
64    /// ```
65    pub fn end(&self) -> usize {
66        self.end
67    }
68
69    /// Gets a reference to the underlying buffer.
70    ///
71    /// This method escapes the slice's view.
72    ///
73    /// # Examples
74    ///
75    /// ```
76    /// use tokio_uring::buf::IoBuf;
77    ///
78    /// let buf = b"hello world".to_vec();
79    /// let slice = buf.slice(..5);
80    ///
81    /// assert_eq!(slice.get_ref(), b"hello world");
82    /// assert_eq!(&slice[..], b"hello");
83    /// ```
84    pub fn get_ref(&self) -> &T {
85        &self.buf
86    }
87
88    /// Gets a mutable reference to the underlying buffer.
89    ///
90    /// This method escapes the slice's view.
91    ///
92    /// # Examples
93    ///
94    /// ```
95    /// use tokio_uring::buf::IoBuf;
96    ///
97    /// let buf = b"hello world".to_vec();
98    /// let mut slice = buf.slice(..5);
99    ///
100    /// slice.get_mut()[0] = b'b';
101    ///
102    /// assert_eq!(slice.get_mut(), b"bello world");
103    /// assert_eq!(&slice[..], b"bello");
104    /// ```
105    pub fn get_mut(&mut self) -> &mut T {
106        &mut self.buf
107    }
108
109    /// Unwraps this `Slice`, returning the underlying buffer.
110    ///
111    /// # Examples
112    ///
113    /// ```
114    /// use tokio_uring::buf::IoBuf;
115    ///
116    /// let buf = b"hello world".to_vec();
117    /// let slice = buf.slice(..5);
118    ///
119    /// let buf = slice.into_inner();
120    /// assert_eq!(buf, b"hello world");
121    /// ```
122    pub fn into_inner(self) -> T {
123        self.buf
124    }
125}
126
127impl<T: IoBuf> ops::Deref for Slice<T> {
128    type Target = [u8];
129
130    fn deref(&self) -> &[u8] {
131        let buf_bytes = super::deref(&self.buf);
132        let end = cmp::min(self.end, buf_bytes.len());
133        &buf_bytes[self.begin..end]
134    }
135}
136
137impl<T: IoBufMut> ops::DerefMut for Slice<T> {
138    fn deref_mut(&mut self) -> &mut [u8] {
139        let buf_bytes = super::deref_mut(&mut self.buf);
140        let end = cmp::min(self.end, buf_bytes.len());
141        &mut buf_bytes[self.begin..end]
142    }
143}
144
145unsafe impl<T: IoBuf> IoBuf for Slice<T> {
146    fn stable_ptr(&self) -> *const u8 {
147        super::deref(&self.buf)[self.begin..].as_ptr()
148    }
149
150    fn bytes_init(&self) -> usize {
151        ops::Deref::deref(self).len()
152    }
153
154    fn bytes_total(&self) -> usize {
155        self.end - self.begin
156    }
157}
158
159unsafe impl<T: IoBufMut> IoBufMut for Slice<T> {
160    fn stable_mut_ptr(&mut self) -> *mut u8 {
161        super::deref_mut(&mut self.buf)[self.begin..].as_mut_ptr()
162    }
163
164    unsafe fn set_init(&mut self, pos: usize) {
165        self.buf.set_init(self.begin + pos);
166    }
167}
fluke_maybe_uring/buf/slice.rs

fluke_maybe_uring/buf/
slice.rs
