| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/bytes-1.4.0/src/buf/uninit_slice.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>uninit_slice.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../bytes/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../bytes/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span>core::fmt; |
| <span class="kw">use </span>core::mem::MaybeUninit; |
| <span class="kw">use </span>core::ops::{ |
| Index, IndexMut, Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive, |
| }; |
| |
| <span class="doccomment">/// Uninitialized byte slice. |
| /// |
| /// Returned by `BufMut::chunk_mut()`, the referenced byte slice may be |
| /// uninitialized. The wrapper provides safe access without introducing |
| /// undefined behavior. |
| /// |
| /// The safety invariants of this wrapper are: |
| /// |
| /// 1. Reading from an `UninitSlice` is undefined behavior. |
| /// 2. Writing uninitialized bytes to an `UninitSlice` is undefined behavior. |
| /// |
| /// The difference between `&mut UninitSlice` and `&mut [MaybeUninit<u8>]` is |
| /// that it is possible in safe code to write uninitialized bytes to an |
| /// `&mut [MaybeUninit<u8>]`, which this type prohibits. |
| </span><span class="attribute">#[repr(transparent)] |
| </span><span class="kw">pub struct </span>UninitSlice([MaybeUninit<u8>]); |
| |
| <span class="kw">impl </span>UninitSlice { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>from_slice(slice: <span class="kw-2">&mut </span>[MaybeUninit<u8>]) -> <span class="kw-2">&mut </span>UninitSlice { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span>(slice <span class="kw">as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>] <span class="kw">as </span><span class="kw-2">*mut </span>UninitSlice) } |
| } |
| |
| <span class="doccomment">/// Create a `&mut UninitSlice` from a pointer and a length. |
| /// |
| /// # Safety |
| /// |
| /// The caller must ensure that `ptr` references a valid memory region owned |
| /// by the caller representing a byte slice for the duration of `'a`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::buf::UninitSlice; |
| /// |
| /// let bytes = b"hello world".to_vec(); |
| /// let ptr = bytes.as_ptr() as *mut _; |
| /// let len = bytes.len(); |
| /// |
| /// let slice = unsafe { UninitSlice::from_raw_parts_mut(ptr, len) }; |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub unsafe fn </span>from_raw_parts_mut<<span class="lifetime">'a</span>>(ptr: <span class="kw-2">*mut </span>u8, len: usize) -> <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>UninitSlice { |
| <span class="kw">let </span>maybe_init: <span class="kw-2">&mut </span>[MaybeUninit<u8>] = |
| core::slice::from_raw_parts_mut(ptr <span class="kw">as </span><span class="kw-2">*mut </span><span class="kw">_</span>, len); |
| <span class="self">Self</span>::from_slice(maybe_init) |
| } |
| |
| <span class="doccomment">/// Write a single byte at the specified offset. |
| /// |
| /// # Panics |
| /// |
| /// The function panics if `index` is out of bounds. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::buf::UninitSlice; |
| /// |
| /// let mut data = [b'f', b'o', b'o']; |
| /// let slice = unsafe { UninitSlice::from_raw_parts_mut(data.as_mut_ptr(), 3) }; |
| /// |
| /// slice.write_byte(0, b'b'); |
| /// |
| /// assert_eq!(b"boo", &data[..]); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>write_byte(<span class="kw-2">&mut </span><span class="self">self</span>, index: usize, byte: u8) { |
| <span class="macro">assert!</span>(index < <span class="self">self</span>.len()); |
| |
| <span class="kw">unsafe </span>{ <span class="self">self</span>[index..].as_mut_ptr().write(byte) } |
| } |
| |
| <span class="doccomment">/// Copies bytes from `src` into `self`. |
| /// |
| /// The length of `src` must be the same as `self`. |
| /// |
| /// # Panics |
| /// |
| /// The function panics if `src` has a different length than `self`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::buf::UninitSlice; |
| /// |
| /// let mut data = [b'f', b'o', b'o']; |
| /// let slice = unsafe { UninitSlice::from_raw_parts_mut(data.as_mut_ptr(), 3) }; |
| /// |
| /// slice.copy_from_slice(b"bar"); |
| /// |
| /// assert_eq!(b"bar", &data[..]); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>copy_from_slice(<span class="kw-2">&mut </span><span class="self">self</span>, src: <span class="kw-2">&</span>[u8]) { |
| <span class="kw">use </span>core::ptr; |
| |
| <span class="macro">assert_eq!</span>(<span class="self">self</span>.len(), src.len()); |
| |
| <span class="kw">unsafe </span>{ |
| ptr::copy_nonoverlapping(src.as_ptr(), <span class="self">self</span>.as_mut_ptr(), <span class="self">self</span>.len()); |
| } |
| } |
| |
| <span class="doccomment">/// Return a raw pointer to the slice's buffer. |
| /// |
| /// # Safety |
| /// |
| /// The caller **must not** read from the referenced memory and **must not** |
| /// write **uninitialized** bytes to the slice either. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::BufMut; |
| /// |
| /// let mut data = [0, 1, 2]; |
| /// let mut slice = &mut data[..]; |
| /// let ptr = BufMut::chunk_mut(&mut slice).as_mut_ptr(); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>as_mut_ptr(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">*mut </span>u8 { |
| <span class="self">self</span>.<span class="number">0</span>.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span><span class="kw">_ |
| </span>} |
| |
| <span class="doccomment">/// Return a `&mut [MaybeUninit<u8>]` to this slice's buffer. |
| /// |
| /// # Safety |
| /// |
| /// The caller **must not** read from the referenced memory and **must not** write |
| /// **uninitialized** bytes to the slice either. This is because `BufMut` implementation |
| /// that created the `UninitSlice` knows which parts are initialized. Writing uninitalized |
| /// bytes to the slice may cause the `BufMut` to read those bytes and trigger undefined |
| /// behavior. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::BufMut; |
| /// |
| /// let mut data = [0, 1, 2]; |
| /// let mut slice = &mut data[..]; |
| /// unsafe { |
| /// let uninit_slice = BufMut::chunk_mut(&mut slice).as_uninit_slice_mut(); |
| /// }; |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub unsafe fn </span>as_uninit_slice_mut<<span class="lifetime">'a</span>>(<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>[MaybeUninit<u8>] { |
| <span class="kw-2">&mut *</span>(<span class="self">self </span><span class="kw">as </span><span class="kw-2">*mut </span><span class="kw">_ as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>]) |
| } |
| |
| <span class="doccomment">/// Returns the number of bytes in the slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use bytes::BufMut; |
| /// |
| /// let mut data = [0, 1, 2]; |
| /// let mut slice = &mut data[..]; |
| /// let len = BufMut::chunk_mut(&mut slice).len(); |
| /// |
| /// assert_eq!(len, 3); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.<span class="number">0</span>.len() |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>UninitSlice { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, fmt: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt.debug_struct(<span class="string">"UninitSlice[...]"</span>).finish() |
| } |
| } |
| |
| <span class="macro">macro_rules! </span>impl_index { |
| ($(<span class="macro-nonterminal">$t</span>:ty),<span class="kw-2">*</span>) => { |
| $( |
| <span class="kw">impl </span>Index<<span class="macro-nonterminal">$t</span>> <span class="kw">for </span>UninitSlice { |
| <span class="kw">type </span>Output = UninitSlice; |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>index(<span class="kw-2">&</span><span class="self">self</span>, index: <span class="macro-nonterminal">$t</span>) -> <span class="kw-2">&</span>UninitSlice { |
| <span class="kw">let </span>maybe_uninit: <span class="kw-2">&</span>[MaybeUninit<u8>] = <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>[index]; |
| <span class="kw">unsafe </span>{ <span class="kw-2">&*</span>(maybe_uninit <span class="kw">as </span><span class="kw-2">*const </span>[MaybeUninit<u8>] <span class="kw">as </span><span class="kw-2">*const </span>UninitSlice) } |
| } |
| } |
| |
| <span class="kw">impl </span>IndexMut<<span class="macro-nonterminal">$t</span>> <span class="kw">for </span>UninitSlice { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>index_mut(<span class="kw-2">&mut </span><span class="self">self</span>, index: <span class="macro-nonterminal">$t</span>) -> <span class="kw-2">&mut </span>UninitSlice { |
| <span class="kw">let </span>maybe_uninit: <span class="kw-2">&mut </span>[MaybeUninit<u8>] = <span class="kw-2">&mut </span><span class="self">self</span>.<span class="number">0</span>[index]; |
| <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span>(maybe_uninit <span class="kw">as </span><span class="kw-2">*mut </span>[MaybeUninit<u8>] <span class="kw">as </span><span class="kw-2">*mut </span>UninitSlice) } |
| } |
| } |
| )* |
| }; |
| } |
| |
| <span class="macro">impl_index!</span>( |
| Range<usize>, |
| RangeFrom<usize>, |
| RangeFull, |
| RangeInclusive<usize>, |
| RangeTo<usize>, |
| RangeToInclusive<usize> |
| ); |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="bytes" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
