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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="Search for regex matches in `&[u8]` haystacks."><title>regex::bytes - 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="regex" 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 mod"><!--[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="../../regex/index.html">regex</a><span class="version">1.10.3</span></h2></div><h2 class="location"><a href="#">Module bytes</a></h2><div class="sidebar-elems"><section><ul class="block"><li><a href="#structs">Structs</a></li><li><a href="#traits">Traits</a></li></ul></section><h2><a href="../index.html">In crate regex</a></h2></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="../../regex/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>Module <a href="../index.html">regex</a>::<wbr><a class="mod" href="#">bytes</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/regex/bytes.rs.html#1-91">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Search for regex matches in <code>&[u8]</code> haystacks.</p>
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<p>This module provides a nearly identical API via <a href="struct.Regex.html" title="struct regex::bytes::Regex"><code>Regex</code></a> to the one found in
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the top-level of this crate. There are two important differences:</p>
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<ol>
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<li>Matching is done on <code>&[u8]</code> instead of <code>&str</code>. Additionally, <code>Vec<u8></code>
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is used where <code>String</code> would have been used in the top-level API.</li>
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<li>Unicode support can be disabled even when disabling it would result in
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matching invalid UTF-8 bytes.</li>
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</ol>
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<h2 id="example-match-null-terminated-string"><a href="#example-match-null-terminated-string">Example: match null terminated string</a></h2>
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<p>This shows how to find all null-terminated strings in a slice of bytes. This
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works even if a C string contains invalid UTF-8.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>regex::bytes::Regex;
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<span class="kw">let </span>re = Regex::new(<span class="string">r"(?-u)(?<cstr>[^\x00]+)\x00"</span>).unwrap();
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<span class="kw">let </span>hay = <span class="string">b"foo\x00qu\xFFux\x00baz\x00"</span>;
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<span class="comment">// Extract all of the strings without the NUL terminator from each match.
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// The unwrap is OK here since a match requires the `cstr` capture to match.
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</span><span class="kw">let </span>cstrs: Vec<<span class="kw-2">&</span>[u8]> =
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re.captures_iter(hay)
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.map(|c| c.name(<span class="string">"cstr"</span>).unwrap().as_bytes())
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.collect();
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<span class="macro">assert_eq!</span>(cstrs, <span class="macro">vec!</span>[<span class="kw-2">&</span><span class="string">b"foo"</span>[..], <span class="kw-2">&</span><span class="string">b"qu\xFFux"</span>[..], <span class="kw-2">&</span><span class="string">b"baz"</span>[..]]);</code></pre></div>
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<h2 id="example-selectively-enable-unicode-support"><a href="#example-selectively-enable-unicode-support">Example: selectively enable Unicode support</a></h2>
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<p>This shows how to match an arbitrary byte pattern followed by a UTF-8 encoded
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string (e.g., to extract a title from a Matroska file):</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>regex::bytes::Regex;
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<span class="kw">let </span>re = Regex::new(
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<span class="string">r"(?-u)\x7b\xa9(?:[\x80-\xfe]|[\x40-\xff].)(?u:(.*))"
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</span>).unwrap();
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<span class="kw">let </span>hay = <span class="string">b"\x12\xd0\x3b\x5f\x7b\xa9\x85\xe2\x98\x83\x80\x98\x54\x76\x68\x65"</span>;
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<span class="comment">// Notice that despite the `.*` at the end, it will only match valid UTF-8
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// because Unicode mode was enabled with the `u` flag. Without the `u` flag,
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// the `.*` would match the rest of the bytes regardless of whether they were
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// valid UTF-8.
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</span><span class="kw">let </span>(<span class="kw">_</span>, [title]) = re.captures(hay).unwrap().extract();
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<span class="macro">assert_eq!</span>(title, <span class="string">b"\xE2\x98\x83"</span>);
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<span class="comment">// We can UTF-8 decode the title now. And the unwrap here
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// is correct because the existence of a match guarantees
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// that `title` is valid UTF-8.
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</span><span class="kw">let </span>title = std::str::from_utf8(title).unwrap();
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<span class="macro">assert_eq!</span>(title, <span class="string">"☃"</span>);</code></pre></div>
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<p>In general, if the Unicode flag is enabled in a capture group and that capture
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is part of the overall match, then the capture is <em>guaranteed</em> to be valid
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UTF-8.</p>
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<h2 id="syntax"><a href="#syntax">Syntax</a></h2>
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<p>The supported syntax is pretty much the same as the syntax for Unicode
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regular expressions with a few changes that make sense for matching arbitrary
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bytes:</p>
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<ol>
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<li>The <code>u</code> flag can be disabled even when disabling it might cause the regex to
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match invalid UTF-8. When the <code>u</code> flag is disabled, the regex is said to be in
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“ASCII compatible” mode.</li>
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<li>In ASCII compatible mode, Unicode character classes are not allowed. Literal
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Unicode scalar values outside of character classes are allowed.</li>
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<li>In ASCII compatible mode, Perl character classes (<code>\w</code>, <code>\d</code> and <code>\s</code>)
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revert to their typical ASCII definition. <code>\w</code> maps to <code>[[:word:]]</code>, <code>\d</code> maps
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to <code>[[:digit:]]</code> and <code>\s</code> maps to <code>[[:space:]]</code>.</li>
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<li>In ASCII compatible mode, word boundaries use the ASCII compatible <code>\w</code> to
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determine whether a byte is a word byte or not.</li>
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<li>Hexadecimal notation can be used to specify arbitrary bytes instead of
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Unicode codepoints. For example, in ASCII compatible mode, <code>\xFF</code> matches the
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literal byte <code>\xFF</code>, while in Unicode mode, <code>\xFF</code> is the Unicode codepoint
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<code>U+00FF</code> that matches its UTF-8 encoding of <code>\xC3\xBF</code>. Similarly for octal
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notation when enabled.</li>
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<li>In ASCII compatible mode, <code>.</code> matches any <em>byte</em> except for <code>\n</code>. When the
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<code>s</code> flag is additionally enabled, <code>.</code> matches any byte.</li>
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</ol>
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<h2 id="performance"><a href="#performance">Performance</a></h2>
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<p>In general, one should expect performance on <code>&[u8]</code> to be roughly similar to
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performance on <code>&str</code>.</p>
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</div></details><h2 id="structs" class="section-header"><a href="#structs">Structs</a></h2><ul class="item-table"><li><div class="item-name"><a class="struct" href="struct.CaptureLocations.html" title="struct regex::bytes::CaptureLocations">CaptureLocations</a></div><div class="desc docblock-short">A low level representation of the byte offsets of each capture group.</div></li><li><div class="item-name"><a class="struct" href="struct.CaptureMatches.html" title="struct regex::bytes::CaptureMatches">CaptureMatches</a></div><div class="desc docblock-short">An iterator over all non-overlapping capture matches in a haystack.</div></li><li><div class="item-name"><a class="struct" href="struct.CaptureNames.html" title="struct regex::bytes::CaptureNames">CaptureNames</a></div><div class="desc docblock-short">An iterator over the names of all capture groups in a regex.</div></li><li><div class="item-name"><a class="struct" href="struct.Captures.html" title="struct regex::bytes::Captures">Captures</a></div><div class="desc docblock-short">Represents the capture groups for a single match.</div></li><li><div class="item-name"><a class="struct" href="struct.Match.html" title="struct regex::bytes::Match">Match</a></div><div class="desc docblock-short">Represents a single match of a regex in a haystack.</div></li><li><div class="item-name"><a class="struct" href="struct.Matches.html" title="struct regex::bytes::Matches">Matches</a></div><div class="desc docblock-short">An iterator over all non-overlapping matches in a haystack.</div></li><li><div class="item-name"><a class="struct" href="struct.NoExpand.html" title="struct regex::bytes::NoExpand">NoExpand</a></div><div class="desc docblock-short">A helper type for forcing literal string replacement.</div></li><li><div class="item-name"><a class="struct" href="struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></div><div class="desc docblock-short">A compiled regular expression for searching Unicode haystacks.</div></li><li><div class="item-name"><a class="struct" href="struct.RegexBuilder.html" title="struct regex::bytes::RegexBuilder">RegexBuilder</a></div><div class="desc docblock-short">A configurable builder for a <a href="struct.Regex.html" title="struct regex::bytes::Regex"><code>Regex</code></a>.</div></li><li><div class="item-name"><a class="struct" href="struct.RegexSet.html" title="struct regex::bytes::RegexSet">RegexSet</a></div><div class="desc docblock-short">Match multiple, possibly overlapping, regexes in a single search.</div></li><li><div class="item-name"><a class="struct" href="struct.RegexSetBuilder.html" title="struct regex::bytes::RegexSetBuilder">RegexSetBuilder</a></div><div class="desc docblock-short">A configurable builder for a <a href="struct.RegexSet.html" title="struct regex::bytes::RegexSet"><code>RegexSet</code></a>.</div></li><li><div class="item-name"><a class="struct" href="struct.ReplacerRef.html" title="struct regex::bytes::ReplacerRef">ReplacerRef</a></div><div class="desc docblock-short">A by-reference adaptor for a <a href="trait.Replacer.html" title="trait regex::bytes::Replacer"><code>Replacer</code></a>.</div></li><li><div class="item-name"><a class="struct" href="struct.SetMatches.html" title="struct regex::bytes::SetMatches">SetMatches</a></div><div class="desc docblock-short">A set of matches returned by a regex set.</div></li><li><div class="item-name"><a class="struct" href="struct.SetMatchesIntoIter.html" title="struct regex::bytes::SetMatchesIntoIter">SetMatchesIntoIter</a></div><div class="desc docblock-short">An owned iterator over the set of matches from a regex set.</div></li><li><div class="item-name"><a class="struct" href="struct.SetMatchesIter.html" title="struct regex::bytes::SetMatchesIter">SetMatchesIter</a></div><div class="desc docblock-short">A borrowed iterator over the set of matches from a regex set.</div></li><li><div class="item-name"><a class="struct" href="struct.Split.html" title="struct regex::bytes::Split">Split</a></div><div class="desc docblock-short">An iterator over all substrings delimited by a
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