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112 lines
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<!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="Types that can be split in two."><title>SplitAt in zerocopy - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="zerocopy" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../static.files/storage-e2aeef58.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.svg"></head><body class="rustdoc trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">SplitAt</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../zerocopy/index.html">zerocopy</a><span class="version">0.8.39</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">SplitAt</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#implementation" title="Implementation">Implementation</a></li><li><a href="#safety" title="Safety">Safety</a></li></ul><h3><a href="#required-associated-types">Required Associated Types</a></h3><ul class="block"><li><a href="#associatedtype.Elem" title="Elem">Elem</a></li></ul><h3><a href="#provided-methods">Provided Methods</a></h3><ul class="block"><li><a href="#method.split_at" title="split_at">split_at</a></li><li><a href="#method.split_at_mut" title="split_at_mut">split_at_mut</a></li><li><a href="#method.split_at_mut_unchecked" title="split_at_mut_unchecked">split_at_mut_unchecked</a></li><li><a href="#method.split_at_unchecked" title="split_at_unchecked">split_at_unchecked</a></li></ul><h3><a href="#foreign-impls">Implementations on Foreign Types</a></h3><ul class="block"><li><a href="#impl-SplitAt-for-%5BT%5D" title="[T]">[T]</a></li></ul><h3><a href="#dyn-compatibility">Dyn Compatibility</a></h3><h3><a href="#implementors">Implementors</a></h3></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="index.html">In crate zerocopy</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="index.html">zerocopy</a></div><h1>Trait <span class="trait">SplitAt</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/zerocopy/split_at.rs.html#61-204">Source</a> </span></div><pre class="rust item-decl"><code>pub unsafe trait SplitAt: <a class="trait" href="trait.KnownLayout.html" title="trait zerocopy::KnownLayout">KnownLayout</a><PointerMetadata = <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>> {
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type <a href="#associatedtype.Elem" class="associatedtype">Elem</a>;
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// Provided methods
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unsafe fn <a href="#method.split_at_unchecked" class="fn">split_at_unchecked</a>(&self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&Self> { ... }
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<span class="item-spacer"></span> fn <a href="#method.split_at" class="fn">split_at</a>(&self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&Self>> { ... }
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<span class="item-spacer"></span> unsafe fn <a href="#method.split_at_mut_unchecked" class="fn">split_at_mut_unchecked</a>(
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&mut self,
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l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>,
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) -> <a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&mut Self> { ... }
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<span class="item-spacer"></span> fn <a href="#method.split_at_mut" class="fn">split_at_mut</a>(&mut self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&mut Self>> { ... }
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}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Types that can be split in two.</p>
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<p>This trait generalizes Rust’s existing support for splitting slices to
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support slices and slice-based dynamically-sized types (“slice DSTs”).</p>
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<h2 id="implementation"><a class="doc-anchor" href="#implementation">§</a>Implementation</h2>
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<p><strong>Do not implement this trait yourself!</strong> Instead, use
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<a href="derive.SplitAt.html" title="derive zerocopy::SplitAt"><code>#[derive(SplitAt)]</code></a>; e.g.:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attr">#[derive(SplitAt, KnownLayout)]
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#[repr(C)]
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</span><span class="kw">struct </span>MyStruct<T: <span class="question-mark">?</span>Sized> {
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...,
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<span class="comment">// `SplitAt` types must have at least one field.
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</span>field: T,
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}</code></pre></div>
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<p>This derive performs a sophisticated, compile-time safety analysis to
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determine whether a type is <code>SplitAt</code>.</p>
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<h2 id="safety"><a class="doc-anchor" href="#safety">§</a>Safety</h2>
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<p>This trait does not convey any safety guarantees to code outside this crate.</p>
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<p>You must not rely on the <code>#[doc(hidden)]</code> internals of <code>SplitAt</code>. Future
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releases of zerocopy may make backwards-breaking changes to these items,
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including changes that only affect soundness, which may cause code which
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uses those items to silently become unsound.</p>
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</div></details><h2 id="required-associated-types" class="section-header">Required Associated Types<a href="#required-associated-types" class="anchor">§</a></h2><div class="methods"><details class="toggle" open><summary><section id="associatedtype.Elem" class="method"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#63">Source</a><h4 class="code-header">type <a href="#associatedtype.Elem" class="associatedtype">Elem</a></h4></section></summary><div class="docblock"><p>The element type of the trailing slice.</p>
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</div></details></div><h2 id="provided-methods" class="section-header">Provided Methods<a href="#provided-methods" class="anchor">§</a></h2><div class="methods"><details class="toggle method-toggle" open><summary><section id="method.split_at_unchecked" class="method"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#78-81">Source</a><h4 class="code-header">unsafe fn <a href="#method.split_at_unchecked" class="fn">split_at_unchecked</a>(&self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&Self></h4></section></summary><div class="docblock"><p>Unsafely splits <code>self</code> in two.</p>
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<h5 id="safety-1"><a class="doc-anchor" href="#safety-1">§</a>Safety</h5>
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<p>The caller promises that <code>l_len</code> is not greater than the length of
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<code>self</code>’s trailing slice.</p>
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</div></details><details class="toggle method-toggle" open><summary><section id="method.split_at" class="method"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#122-131">Source</a><h4 class="code-header">fn <a href="#method.split_at" class="fn">split_at</a>(&self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&Self>></h4></section></summary><div class="docblock"><p>Attempts to split <code>self</code> in two.</p>
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<p>Returns <code>None</code> if <code>l_len</code> is greater than the length of <code>self</code>’s
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trailing slice.</p>
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<h5 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>zerocopy::{SplitAt, FromBytes};
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<span class="attr">#[derive(SplitAt, FromBytes, KnownLayout, Immutable)]
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#[repr(C)]
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</span><span class="kw">struct </span>Packet {
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length: u8,
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body: [u8],
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}
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<span class="comment">// These bytes encode a `Packet`.
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</span><span class="kw">let </span>bytes = <span class="kw-2">&</span>[<span class="number">4</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>][..];
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<span class="kw">let </span>packet = Packet::ref_from_bytes(bytes).unwrap();
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<span class="macro">assert_eq!</span>(packet.length, <span class="number">4</span>);
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<span class="macro">assert_eq!</span>(packet.body, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]);
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<span class="comment">// Attempt to split `packet` at `length`.
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</span><span class="kw">let </span>split = packet.split_at(packet.length <span class="kw">as </span>usize).unwrap();
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<span class="comment">// Use the `Immutable` bound on `Packet` to prove that it's okay to
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// return concurrent references to `packet` and `rest`.
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</span><span class="kw">let </span>(packet, rest) = split.via_immutable();
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<span class="macro">assert_eq!</span>(packet.length, <span class="number">4</span>);
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<span class="macro">assert_eq!</span>(packet.body, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]);
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<span class="macro">assert_eq!</span>(rest, [<span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]);</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.split_at_mut_unchecked" class="method"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#141-144">Source</a><h4 class="code-header">unsafe fn <a href="#method.split_at_mut_unchecked" class="fn">split_at_mut_unchecked</a>(&mut self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&mut Self></h4></section></summary><div class="docblock"><p>Unsafely splits <code>self</code> in two.</p>
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<h5 id="safety-2"><a class="doc-anchor" href="#safety-2">§</a>Safety</h5>
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<p>The caller promises that <code>l_len</code> is not greater than the length of
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<code>self</code>’s trailing slice.</p>
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</div></details><details class="toggle method-toggle" open><summary><section id="method.split_at_mut" class="method"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#194-203">Source</a><h4 class="code-header">fn <a href="#method.split_at_mut" class="fn">split_at_mut</a>(&mut self, l_len: <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.usize.html">usize</a>) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="struct.Split.html" title="struct zerocopy::Split">Split</a><&mut Self>></h4></section></summary><div class="docblock"><p>Attempts to split <code>self</code> in two.</p>
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<p>Returns <code>None</code> if <code>l_len</code> is greater than the length of <code>self</code>’s
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trailing slice, or if the given <code>l_len</code> would result in <a href="trait.KnownLayout.html#slice-dst-layout" title="trait zerocopy::KnownLayout">the trailing
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padding</a> of the left portion overlapping
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the right portion.</p>
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<h5 id="examples-1"><a class="doc-anchor" href="#examples-1">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>zerocopy::{SplitAt, FromBytes};
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<span class="attr">#[derive(SplitAt, FromBytes, KnownLayout, IntoBytes)]
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#[repr(C)]
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</span><span class="kw">struct </span>Packet<B: <span class="question-mark">?</span>Sized> {
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length: u8,
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body: B,
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}
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<span class="comment">// These bytes encode a `Packet`.
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</span><span class="kw">let </span><span class="kw-2">mut </span>bytes = <span class="kw-2">&mut </span>[<span class="number">4</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>][..];
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<span class="kw">let </span>packet = Packet::<[u8]>::mut_from_bytes(bytes).unwrap();
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<span class="macro">assert_eq!</span>(packet.length, <span class="number">4</span>);
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<span class="macro">assert_eq!</span>(packet.body, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]);
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{
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<span class="comment">// Attempt to split `packet` at `length`.
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</span><span class="kw">let </span>split = packet.split_at_mut(packet.length <span class="kw">as </span>usize).unwrap();
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<span class="comment">// Use the `IntoBytes` bound on `Packet` to prove that it's okay to
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// return concurrent references to `packet` and `rest`.
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</span><span class="kw">let </span>(packet, rest) = split.via_into_bytes();
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<span class="macro">assert_eq!</span>(packet.length, <span class="number">4</span>);
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<span class="macro">assert_eq!</span>(packet.body, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]);
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<span class="macro">assert_eq!</span>(rest, [<span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]);
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rest.fill(<span class="number">0</span>);
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}
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<span class="macro">assert_eq!</span>(packet.length, <span class="number">4</span>);
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<span class="macro">assert_eq!</span>(packet.body, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>]);</code></pre></div></div></details></div><h2 id="dyn-compatibility" class="section-header">Dyn Compatibility<a href="#dyn-compatibility" class="anchor">§</a></h2><div class="dyn-compatibility-info"><p>This trait is <b>not</b> <a href="https://doc.rust-lang.org/1.93.1/reference/items/traits.html#dyn-compatibility">dyn compatible</a>.</p><p><i>In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.</i></p></div><h2 id="foreign-impls" class="section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor">§</a></h2><details class="toggle implementors-toggle"><summary><section id="impl-SplitAt-for-%5BT%5D" class="impl"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#207-217">Source</a><a href="#impl-SplitAt-for-%5BT%5D" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="trait.SplitAt.html" title="trait zerocopy::SplitAt">SplitAt</a> for <a class="primitive" href="https://doc.rust-lang.org/1.93.1/core/primitive.slice.html">[T]</a></h3></section></summary><div class="impl-items"><section id="associatedtype.Elem-1" class="associatedtype trait-impl"><a class="src rightside" href="../src/zerocopy/split_at.rs.html#208">Source</a><a href="#associatedtype.Elem-1" class="anchor">§</a><h4 class="code-header">type <a href="#associatedtype.Elem" class="associatedtype">Elem</a> = T</h4></section></div></details><h2 id="implementors" class="section-header">Implementors<a href="#implementors" class="anchor">§</a></h2><div id="implementors-list"></div><script src="../trait.impl/zerocopy/split_at/trait.SplitAt.js" data-ignore-extern-crates="core" async></script></section></div></main></body></html> |