<!DOCTYPE html><htmllang="en"><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metaname="generator"content="rustdoc"><metaname="description"content="Provides types for dealing with capturing groups."><title>regex_automata::util::captures - Rust</title><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><linkrel="stylesheet"href="../../../static.files/normalize-76eba96aa4d2e634.css"><linkrel="stylesheet"href="../../../static.files/rustdoc-5bc39a1768837dd0.css"><metaname="rustdoc-vars"data-root-path="../../../"data-static-root-path="../../../static.files/"data-current-crate="regex_automata"data-themes=""data-resource-suffix=""data-rustdoc-version="1.77.0 (aedd173a2 2024-03-17)"data-channel="1.77.0"data-search-js="search-dd67cee4cfa65049.js"data-settings-js="settings-4313503d2e1961c2.js"><scriptsrc="../../../static.files/storage-4c98445ec4002617.js"></script><scriptdefersrc="../sidebar-items.js"></script><scriptdefersrc="../../../static.files/main-48f368f3872407c8.js"></script><noscript><linkrel="stylesheet"href="../../../static.files/noscript-04d5337699b92874.css"></noscript><linkrel="alternate icon"type="image/png"href="../../../static.files/favicon-16x16-8b506e7a72182f1c.png"><linkrel="alternate icon"type="image/png"href="../../../static.files/favicon-32x32-422f7d1d52889060.png"><linkrel="icon"type="image/svg+xml"href="../../../static.files/favicon-2c020d218678b618.svg"></head><bodyclass="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><navclass="mobile-topbar"><buttonclass="sidebar-menu-toggle"title="show sidebar"></button></nav><navclass="sidebar"><divclass="sidebar-crate"><h2><ahref="../../../regex_automata/index.html">regex_automata</a><spanclass="version">0.4.6</span></h2></div><h2class="location"><ahref="#">Module captures</a></h2><divclass="sidebar-elems"><section><ulclass="block"><li><ahref="#structs">Structs</a></li></ul></section><h2><ahref="../index.html">In regex_automata::util</a></h2></div></nav><divclass="sidebar-resizer"></div>
<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../../regex_automata/all.html"title="show sidebar"></a></div><inputclass="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"><divid="help-button"tabindex="-1"><ahref="../../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Module <ahref="../../index.html">regex_automata</a>::<wbr><ahref="../index.html">util</a>::<wbr><aclass="mod"href="#">captures</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../../src/regex_automata/util/captures.rs.html#1-2548">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p>Provides types for dealing with capturing groups.</p>
<p>Capturing groups refer to sub-patterns of regexes that some regex engines can
report matching offsets for. For example, matching <code>[a-z]([0-9]+)</code> against
<code>a789</code> would give <code>a789</code> as the overall match (for the implicit capturing group
at index <code>0</code>) and <code>789</code> as the match for the capturing group <code>([0-9]+)</code> (an
explicit capturing group at index <code>1</code>).</p>
<p>Not all regex engines can report match offsets for capturing groups. Indeed,
to a first approximation, regex engines that can report capturing group offsets
tend to be quite a bit slower than regex engines that can’t. This is because
tracking capturing groups at search time usually requires more “power” that
in turn adds overhead.</p>
<p>Other regex implementations might call capturing groups “submatches.”</p>
<li><ahref="struct.Captures.html"title="struct regex_automata::util::captures::Captures"><code>Captures</code></a> records the capturing group offsets found during a search. It
provides convenience routines for looking up capturing group offsets by either
index or name.</li>
<li><ahref="struct.GroupInfo.html"title="struct regex_automata::util::captures::GroupInfo"><code>GroupInfo</code></a> records the mapping between capturing groups and “slots,”
where the latter are how capturing groups are recorded during a regex search.
This also keeps a mapping from capturing group name to index, and capture
group index to name. A <code>GroupInfo</code> is used by <code>Captures</code> internally to
provide a convenient API. It is unlikely that you’ll use a <code>GroupInfo</code>
directly, but for example, if you’ve compiled an Thompson NFA, then you can use
<ahref="../../nfa/thompson/struct.NFA.html#method.group_info"title="method regex_automata::nfa::thompson::NFA::group_info"><code>thompson::NFA::group_info</code></a> to get its
</div></details><h2id="structs"class="section-header">Structs<ahref="#structs"class="anchor">§</a></h2><ulclass="item-table"><li><divclass="item-name"><aclass="struct"href="struct.Captures.html"title="struct regex_automata::util::captures::Captures">Captures</a></div><divclass="desc docblock-short">The span offsets of capturing groups after a match has been found.</div></li><li><divclass="item-name"><aclass="struct"href="struct.CapturesPatternIter.html"title="struct regex_automata::util::captures::CapturesPatternIter">CapturesPatternIter</a></div><divclass="desc docblock-short">An iterator over all capturing groups in a <code>Captures</code> value.</div></li><li><divclass="item-name"><aclass="struct"href="struct.GroupInfo.html"title="struct regex_automata::util::captures::GroupInfo">GroupInfo</a></div><divclass="desc docblock-short">Represents information about capturing groups in a compiled regex.</div></li><li><divclass="item-name"><aclass="struct"href="struct.GroupInfoAllNames.html"title="struct regex_automata::util::captures::GroupInfoAllNames">GroupInfoAllNames</a></div><divclass="desc docblock-short">An iterator over capturing groups and their names for a <code>GroupInfo</code>.</div></li><li><divclass="item-name"><aclass="struct"href="struct.GroupInfoError.html"title="struct regex_automata::util::captures::GroupInfoError">GroupInfoError</a></div><divclass="desc docblock-short">An error that may occur when building a <code>GroupInfo</code>.</div></li><li><divclass="item-name"><aclass="struct"href="struct.GroupInfoPatternNames.html"title="struct regex_automata::util::captures::GroupInfoPatternNames">GroupInfoPatternNames</a></div><divclass="desc docblock-short">An iterator over capturing groups and their names for a specific pattern.</div></li></ul></section></div></main></body></html>
