<!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 `DoubleEndedSearcher` trait in crate `alloc`."><meta name="keywords" content="rust, rustlang, rust-lang, DoubleEndedSearcher"><title>alloc::str::pattern::DoubleEndedSearcher - 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><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></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='../../../alloc/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><p class='location'>Trait DoubleEndedSearcher</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='../../index.html'>alloc</a>::<wbr><a href='../index.html'>str</a>::<wbr><a href='index.html'>pattern</a></p><script>window.sidebarCurrent = {name: 'DoubleEndedSearcher', 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 js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><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='in-band'>Trait <a href='../../index.html'>alloc</a>::<wbr><a href='../index.html'>str</a>::<wbr><a href='index.html'>pattern</a>::<wbr><a class="trait" href=''>DoubleEndedSearcher</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version '></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='../../../src/core/str/pattern.rs.html#244' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust trait'>pub trait DoubleEndedSearcher<'a>: <a class="trait" href="../../../alloc/str/pattern/trait.ReverseSearcher.html" title="trait alloc::str::pattern::ReverseSearcher">ReverseSearcher</a><'a> { }</pre></div><div class='stability'><div class='stab unstable'><details><summary><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>pattern </code><a href="https://github.com/rust-lang/rust/issues/27721">#27721</a>)</summary><p>API not fully fleshed out and ready to be stabilized</p>
</details></div></div><div class='docblock'><p>A marker trait to express that a <code>ReverseSearcher</code>
can be used for a <code>DoubleEndedIterator</code> implementation.</p>
<p>For this, the impl of <code>Searcher</code> and <code>ReverseSearcher</code> need
to follow these conditions:</p>
<ul>
<li>All results of <code>next()</code> need to be identical
to the results of <code>next_back()</code> in reverse order.</li>
<li><code>next()</code> and <code>next_back()</code> need to behave as
the two ends of a range of values, that is they
can not "walk past each other".</li>
</ul>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p><code>char::Searcher</code> is a <code>DoubleEndedSearcher</code> because searching for a
<code>char</code> only requires looking at one at a time, which behaves the same
from both ends.</p>
<p><code>(&str)::Searcher</code> is not a <code>DoubleEndedSearcher</code> because
the pattern <code>"aa"</code> in the haystack <code>"aaa"</code> matches as either
<code>"[aa]a"</code> or <code>"a[aa]"</code>, depending from which side it is searched.</p>
</div>
<h2 id='implementors' class='small-section-header'>
Implementors<a href='#implementors' class='anchor'></a>
</h2>
<ul class='item-list' id='implementors-list'>
<li><table class='table-display'><tbody><tr><td><code>impl<'a> DoubleEndedSearcher<'a> for <a class="struct" href="../../../alloc/str/pattern/struct.CharSearcher.html" title="struct alloc::str::pattern::CharSearcher">CharSearcher</a><'a></code><td><div class='out-of-band'><a class='srclink' href='../../../src/core/str/pattern.rs.html#429' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<'a, F> DoubleEndedSearcher<'a> for <a class="struct" href="../../../alloc/str/pattern/struct.CharPredicateSearcher.html" title="struct alloc::str::pattern::CharPredicateSearcher">CharPredicateSearcher</a><'a, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../../core/ops/function/trait.FnMut.html" title="trait core::ops::function::FnMut">FnMut</a>(char) -> bool, </span></code><td><div class='out-of-band'><a class='srclink' href='../../../src/core/str/pattern.rs.html#691-692' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<'a, 'b> DoubleEndedSearcher<'a> for <a class="struct" href="../../../alloc/str/pattern/struct.CharSliceSearcher.html" title="struct alloc::str::pattern::CharSliceSearcher">CharSliceSearcher</a><'a, 'b></code><td><div class='out-of-band'><a class='srclink' href='../../../src/core/str/pattern.rs.html#653' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
</ul><script type="text/javascript">window.inlined_types=new Set([]);</script><script type="text/javascript" async
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