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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 `Into` trait in crate `nom`."><meta name="keywords" content="rust, rustlang, rust-lang, Into"><title>nom::lib::std::convert::Into - 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 trait"><!--[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">☰</div><a href='../../../../nom/index.html'><div class='logo-container'><img src='../../../../rust-logo.png' alt='logo'></div></a><p class='location'>Trait Into</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#required-methods">Required Methods</a><div class="sidebar-links"><a href="#tymethod.into">into</a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='../../../index.html'>nom</a>::<wbr><a href='../../index.html'>lib</a>::<wbr><a href='../index.html'>std</a>::<wbr><a href='index.html'>convert</a></p><script>window.sidebarCurrent = {name: 'Into', ty: 'trait', 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"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled 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 class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#287-291' title='goto source code'>[src]</a></span><span class='in-band'>Trait <a href='../../../index.html'>nom</a>::<wbr><a href='../../index.html'>lib</a>::<wbr><a href='../index.html'>std</a>::<wbr><a href='index.html'>convert</a>::<wbr><a class="trait" href=''>Into</a></span></h1><div class="docblock type-decl hidden-by-usual-hider"><pre class='rust trait'>pub trait Into<T> {
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fn <a href='#tymethod.into' class='fnname'>into</a>(self) -> T;
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}</pre></div><div class='docblock'><p>A value-to-value conversion that consumes the input value. The
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opposite of <a href="trait.From.html"><code>From</code></a>.</p>
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<p>One should avoid implementing <a href="trait.Into.html"><code>Into</code></a> and implement <a href="trait.From.html"><code>From</code></a> instead.
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Implementing <a href="trait.From.html"><code>From</code></a> automatically provides one with an implementation of <a href="trait.Into.html"><code>Into</code></a>
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thanks to the blanket implementation in the standard library.</p>
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<p>Prefer using <a href="trait.Into.html"><code>Into</code></a> over <a href="trait.From.html"><code>From</code></a> when specifying trait bounds on a generic function
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to ensure that types that only implement <a href="trait.Into.html"><code>Into</code></a> can be used as well.</p>
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<p><strong>Note: This trait must not fail</strong>. If the conversion can fail, use <a href="trait.TryInto.html"><code>TryInto</code></a>.</p>
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<h1 id="generic-implementations" class="section-header"><a href="#generic-implementations">Generic Implementations</a></h1>
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<ul>
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<li><a href="trait.From.html"><code>From</code></a><code><T> for U</code> implies <code>Into<U> for T</code></li>
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<li><a href="trait.Into.html"><code>Into</code></a> is reflexive, which means that <code>Into<T> for T</code> is implemented</li>
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</ul>
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<h1 id="implementing-into-for-conversions-to-external-types-in-old-versions-of-rust" class="section-header"><a href="#implementing-into-for-conversions-to-external-types-in-old-versions-of-rust">Implementing <code>Into</code> for conversions to external types in old versions of Rust</a></h1>
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<p>Prior to Rust 1.41, if the destination type was not part of the current crate
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then you couldn't implement <a href="trait.From.html"><code>From</code></a> directly.
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For example, take this code:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">struct</span> <span class="ident">Wrapper</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
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<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">Wrapper</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span> <span class="kw">for</span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
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<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">w</span>: <span class="ident">Wrapper</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
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<span class="ident">w</span>.<span class="number">0</span>
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}
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}</pre></div>
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<p>This will fail to compile in older versions of the language because Rust's orphaning rules
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used to be a little bit more strict. To bypass this, you could implement <a href="trait.Into.html"><code>Into</code></a> directly:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">struct</span> <span class="ident">Wrapper</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
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<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Into</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span> <span class="kw">for</span> <span class="ident">Wrapper</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
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<span class="kw">fn</span> <span class="ident">into</span>(<span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
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<span class="self">self</span>.<span class="number">0</span>
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}
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}</pre></div>
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<p>It is important to understand that <a href="trait.Into.html"><code>Into</code></a> does not provide a <a href="trait.From.html"><code>From</code></a> implementation
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(as <a href="trait.From.html"><code>From</code></a> does with <a href="trait.Into.html"><code>Into</code></a>). Therefore, you should always try to implement <a href="trait.From.html"><code>From</code></a>
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and then fall back to <a href="trait.Into.html"><code>Into</code></a> if <a href="trait.From.html"><code>From</code></a> can't be implemented.</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<p><a href="../../std/string/struct.String.html"><code>String</code></a> implements <a href="trait.Into.html"><code>Into</code></a><code><</code><a href="../../std/vec/struct.Vec.html"><code>Vec</code></a><code><</code>[<code>u8</code>]<code>>></code>:</p>
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<p>In order to express that we want a generic function to take all arguments that can be
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converted to a specified type <code>T</code>, we can use a trait bound of <a href="trait.Into.html"><code>Into</code></a><code><T></code>.
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For example: The function <code>is_hello</code> takes all arguments that can be converted into a
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<a href="../../std/vec/struct.Vec.html"><code>Vec</code></a><code><</code>[<code>u8</code>]<code>></code>.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">fn</span> <span class="ident">is_hello</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Into</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span><span class="op">></span>(<span class="ident">s</span>: <span class="ident">T</span>) {
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<span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> <span class="string">b"hello"</span>.<span class="ident">to_vec</span>();
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">bytes</span>, <span class="ident">s</span>.<span class="ident">into</span>());
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}
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<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="string">"hello"</span>.<span class="ident">to_string</span>();
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<span class="ident">is_hello</span>(<span class="ident">s</span>);</pre></div>
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</div>
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<h2 id='required-methods' class='small-section-header'>Required methods<a href='#required-methods' class='anchor'></a></h2><div class='methods'><h3 id='tymethod.into' class='method'><code id='into.v'>fn <a href='#tymethod.into' class='fnname'>into</a>(self) -> T</code></h3><div class='docblock'><p>Performs the conversion.</p>
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</div></div><span class='loading-content'>Loading content...</span>
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<h2 id='implementors' class='small-section-header'>Implementors<a href='#implementors' class='anchor'></a></h2><div class='item-list' id='implementors-list'><h3 id='impl-Into%3CU%3E' class='impl'><code class='in-band'>impl<T, U> Into<U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="../../../../nom/lib/std/prelude/v1/v1/trait.From.html" title="trait nom::lib::std::prelude::v1::v1::From">From</a><T>, </span></code><a href='#impl-Into%3CU%3E' class='anchor'></a><a class='srclink' href='https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#553-560' title='goto source code'>[src]</a></h3><div class='impl-items'><h4 id='method.into' class="method hidden"><code id='into.v-1'>fn <a href='#method.into' class='fnname'>into</a>(self) -> U</code><a class='srclink' href='https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#557-559' title='goto source code'>[src]</a></h4></div></div><span class='loading-content'>Loading content...</span><script type="text/javascript" src="../../../../implementors/core/convert/trait.Into.js" async></script></section><section id="search" class="content hidden"></section><section class="footer"></section><script>window.rootPath = "../../../../";window.currentCrate = "nom";</script><script src="../../../../aliases.js"></script><script src="../../../../main.js"></script><script defer src="../../../../search-index.js"></script></body></html> |