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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="Creates a `Vec` containing the arguments."><title>vec in allocator_api2 - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="allocator_api2" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc macro"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../allocator_api2/index.html">allocator_api2</a><span class="version">0.2.16</span></h2></div><div class="sidebar-elems"></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../allocator_api2/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Macro <a href="index.html">allocator_api2</a>::<wbr><a class="macro" href="#">vec</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../src/allocator_api2/stable/macros.rs.html#56-83">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><pre class="rust item-decl"><span class="macro">macro_rules! </span>vec {
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(<span class="kw">in </span><span class="macro-nonterminal">$alloc</span>:expr $(;)<span class="question-mark">?</span>) => { ... };
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(<span class="kw">in </span><span class="macro-nonterminal">$alloc</span>:expr; <span class="macro-nonterminal">$elem</span>:expr; <span class="macro-nonterminal">$n</span>:expr) => { ... };
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(<span class="kw">in </span><span class="macro-nonterminal">$alloc</span>:expr; $(<span class="macro-nonterminal">$x</span>:expr),+ $(,)<span class="question-mark">?</span>) => { ... };
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() => { ... };
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(<span class="macro-nonterminal">$elem</span>:expr; <span class="macro-nonterminal">$n</span>:expr) => { ... };
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($(<span class="macro-nonterminal">$x</span>:expr),+ $(,)<span class="question-mark">?</span>) => { ... };
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}</pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Creates a <a href="vec/struct.Vec.html" title="struct allocator_api2::vec::Vec"><code>Vec</code></a> containing the arguments.</p>
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<p><code>vec!</code> allows <code>Vec</code>s to be defined with the same syntax as array expressions.
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There are two forms of this macro:</p>
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<ul>
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<li>Create a <a href="vec/struct.Vec.html" title="struct allocator_api2::vec::Vec"><code>Vec</code></a> containing a given list of elements:</li>
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</ul>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>allocator_api2::vec;
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<span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
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<span class="macro">assert_eq!</span>(v[<span class="number">0</span>], <span class="number">1</span>);
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<span class="macro">assert_eq!</span>(v[<span class="number">1</span>], <span class="number">2</span>);
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<span class="macro">assert_eq!</span>(v[<span class="number">2</span>], <span class="number">3</span>);</code></pre></div>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>allocator_api2::{vec, alloc::Global};
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<span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="kw">in </span>Global; <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
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<span class="macro">assert_eq!</span>(v[<span class="number">0</span>], <span class="number">1</span>);
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<span class="macro">assert_eq!</span>(v[<span class="number">1</span>], <span class="number">2</span>);
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<span class="macro">assert_eq!</span>(v[<span class="number">2</span>], <span class="number">3</span>);</code></pre></div>
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<ul>
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<li>Create a <a href="vec/struct.Vec.html" title="struct allocator_api2::vec::Vec"><code>Vec</code></a> from a given element and size:</li>
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</ul>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>allocator_api2::vec;
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<span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="number">1</span>; <span class="number">3</span>];
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<span class="macro">assert_eq!</span>(v, [<span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>]);</code></pre></div>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>allocator_api2::{vec, alloc::Global};
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<span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="kw">in </span>Global; <span class="number">1</span>; <span class="number">3</span>];
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<span class="macro">assert_eq!</span>(v, [<span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>]);</code></pre></div>
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<p>Note that unlike array expressions this syntax supports all elements
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which implement <a href="https://doc.rust-lang.org/1.76.0/core/clone/trait.Clone.html" title="trait core::clone::Clone"><code>Clone</code></a> and the number of elements doesn’t have to be
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a constant.</p>
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<p>This will use <code>clone</code> to duplicate an expression, so one should be careful
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using this with types having a nonstandard <code>Clone</code> implementation. For
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example, <code>vec![Rc::new(1); 5]</code> will create a vector of five references
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to the same boxed integer value, not five references pointing to independently
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boxed integers.</p>
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<p>Also, note that <code>vec![expr; 0]</code> is allowed, and produces an empty vector.
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This will still evaluate <code>expr</code>, however, and immediately drop the resulting value, so
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be mindful of side effects.</p>
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</div></details></section></div></main></body></html> |