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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="API documentation for the Rust `array_refs` macro in crate `arrayref`."><meta name="keywords" content="rust, rustlang, rust-lang, array_refs"><title>arrayref::array_refs - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc macro"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><a href='../arrayref/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='index.html'>arrayref</a></p><script>window.sidebarCurrent = {name: 'array_refs', ty: 'macro', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../src/arrayref/lib.rs.html#105-156' title='goto source code'>[src]</a></span><span class='in-band'>Macro <a href='index.html'>arrayref</a>::<wbr><a class="macro" href=''>array_refs</a></span></h1><div class="docblock type-decl hidden-by-usual-hider"><div class="example-wrap"><pre class="rust macro">
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">array_refs</span> {
( <span class="macro-nonterminal">$</span><span class="macro-nonterminal">arr</span>:<span class="ident">expr</span>, $( <span class="macro-nonterminal">$</span><span class="macro-nonterminal">pre</span>:<span class="ident">expr</span> ),<span class="op">*</span> ; .. ; $( <span class="macro-nonterminal">$</span><span class="macro-nonterminal">post</span>:<span class="ident">expr</span> ),<span class="op">*</span> ) <span class="op">=</span><span class="op">&gt;</span> { ... };
( <span class="macro-nonterminal">$</span><span class="macro-nonterminal">arr</span>:<span class="ident">expr</span>, $( <span class="macro-nonterminal">$</span><span class="macro-nonterminal">len</span>:<span class="ident">expr</span> ),<span class="op">*</span> ) <span class="op">=</span><span class="op">&gt;</span> { ... };
}</pre></div>
</div><div class='docblock'><p>You can use <code>array_refs</code> to generate a series of array references
to an input array reference. The idea is if you want to break an
array into a series of contiguous and non-overlapping arrays.
<code>array_refs</code> is a bit funny in that it insists on slicing up the
<em>entire</em> array. This is intentional, as I find it handy to make
me ensure that my sub-arrays add up to the entire array. This
macro will <em>never</em> panic, since the sizes are all checked at
compile time.</p>
<p>Note that unlike <code>array_ref!</code>, <code>array_refs</code> <em>requires</em> that the
first argument be an array reference. The following arguments are
the lengths of each subarray you wish a reference to. The total
of these arguments <em>must</em> equal the size of the array itself.</p>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">arrayref</span>;
<span class="kw">fn</span> <span class="ident">read_u16</span>(<span class="ident">bytes</span>: <span class="kw-2">&amp;</span>[<span class="ident">u8</span>; <span class="number">2</span>]) <span class="op">-</span><span class="op">&gt;</span> <span class="ident">u16</span> {
<span class="ident">bytes</span>[<span class="number">0</span>] <span class="kw">as</span> <span class="ident">u16</span> <span class="op">+</span> ((<span class="ident">bytes</span>[<span class="number">1</span>] <span class="kw">as</span> <span class="ident">u16</span>) <span class="op">&lt;</span><span class="op">&lt;</span> <span class="number">8</span>)
}
<span class="comment">// ...</span>
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> [<span class="number">0</span>,<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">6</span>,<span class="number">7</span>];
<span class="kw">let</span> (<span class="ident">a</span>,<span class="ident">b</span>,<span class="ident">c</span>) <span class="op">=</span> <span class="macro">array_refs</span><span class="macro">!</span>[<span class="kw-2">&amp;</span><span class="ident">data</span>,<span class="number">2</span>,<span class="number">2</span>,<span class="number">4</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">read_u16</span>(<span class="ident">a</span>), <span class="number">256</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">read_u16</span>(<span class="ident">b</span>), <span class="number">3</span><span class="kw-2">*</span><span class="number">256</span><span class="op">+</span><span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">c</span>, [<span class="number">4</span>,<span class="number">0</span>,<span class="number">6</span>,<span class="number">7</span>]);</pre></div>
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