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<p class='location'>Struct Regex</p><div class="block items"><ul><li><a href="#methods">Methods</a></li><li><a href="#implementations">Trait Implementations</a></li></ul></div><p class='location'><a href='../index.html'>regex</a>::<wbr><a href='index.html'>bytes</a></p><script>window.sidebarCurrent = {name: 'Regex', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Struct <a href='../index.html'>regex</a>::<wbr><a href='index.html'>bytes</a>::<wbr><a class="struct" href=''>Regex</a></span><span class='out-of-band'><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/regex/re_bytes.rs.html#39' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct Regex(_);</pre><div class='docblock'><p>A compiled regular expression for matching arbitrary bytes.</p>
<p>It can be used to search, split or replace text. All searching is done with
an implicit <code>.*?</code> at the beginning and end of an expression. To force an
expression to match the whole string (or a prefix or a suffix), you must
use an anchor like <code>^</code> or <code>$</code> (or <code>\A</code> and <code>\z</code>).</p>
<p>Like the <code>Regex</code> type in the parent module, matches with this regex return
byte offsets into the search text. <strong>Unlike</strong> the parent <code>Regex</code> type,
these byte offsets may not correspond to UTF-8 sequence boundaries since
the regexes in this module can match arbitrary bytes.</p>
</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/regex/re_bytes.rs.html#74-561' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.new' class="method"><span id='new.v' class='invisible'><code>fn <a href='#method.new' class='fnname'>new</a>(re: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a>, <a class="enum" href="../../regex/enum.Error.html" title="enum regex::Error">Error</a>></code></span></h4>
<div class='docblock'><p>Compiles a regular expression. Once compiled, it can be used repeatedly
to search, split or replace text in a string.</p>
<p>If an invalid expression is given, then an error is returned.</p>
</div><h4 id='method.with_size_limit' class="method"><span id='with_size_limit.v' class='invisible'><code>fn <a href='#method.with_size_limit' class='fnname'>with_size_limit</a>(size: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, re: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a>, <a class="enum" href="../../regex/enum.Error.html" title="enum regex::Error">Error</a>></code></span></h4>
<div class='docblock'><p>Compiles a regular expression with the given size limit.</p>
<p>The size limit is applied to the size of the <em>compiled</em> data structure.
If the data structure exceeds the size given, then an error is
returned.</p>
</div><h4 id='method.is_match' class="method"><span id='is_match.v' class='invisible'><code>fn <a href='#method.is_match' class='fnname'>is_match</a>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Returns true if and only if the regex matches the string given.</p>
<p>It is recommended to use this method if all you need to do is test
a match, since the underlying matching engine may be able to do less
work.</p>
<h1 id='example' class='section-header'><a href='#example'>Example</a></h1>
<p>Test if some text contains at least one word with exactly 13 ASCII word
bytes:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"I categorically deny having triskaidekaphobia."</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"\b\w{13}\b"</span>).<span class="ident">unwrap</span>().<span class="ident">is_match</span>(<span class="ident">text</span>));</pre>
</div><h4 id='method.find' class="method"><span id='find.v' class='invisible'><code>fn <a href='#method.find' class='fnname'>find</a>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>></code></span></h4>
<div class='docblock'><p>Returns the start and end byte range of the leftmost-first match in
<code>text</code>. If no match exists, then <code>None</code> is returned.</p>
<p>Note that this should only be used if you want to discover the position
of the match. Testing the existence of a match is faster if you use
<code>is_match</code>.</p>
<h1 id='example-1' class='section-header'><a href='#example-1'>Example</a></h1>
<p>Find the start and end location of the first word with exactly 13
ASCII word bytes:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"I categorically deny having triskaidekaphobia."</span>;
<span class="kw">let</span> <span class="ident">pos</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"\b\w{13}\b"</span>).<span class="ident">unwrap</span>().<span class="ident">find</span>(<span class="ident">text</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">pos</span>, <span class="prelude-val">Some</span>((<span class="number">2</span>, <span class="number">15</span>)));</pre>
</div><h4 id='method.find_iter' class="method"><span id='find_iter.v' class='invisible'><code>fn <a href='#method.find_iter' class='fnname'>find_iter</a><'r, 't>(&'r self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&'t [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="struct" href="../../regex/bytes/struct.FindMatches.html" title="struct regex::bytes::FindMatches">FindMatches</a><'r, 't></code></span></h4>
<div class='docblock'><p>Returns an iterator for each successive non-overlapping match in
<code>text</code>, returning the start and end byte indices with respect to
<code>text</code>.</p>
<h1 id='example-2' class='section-header'><a href='#example-2'>Example</a></h1>
<p>Find the start and end location of every word with exactly 13 ASCII
word bytes:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"Retroactively relinquishing remunerations is reprehensible."</span>;
<span class="kw">for</span> <span class="ident">pos</span> <span class="kw">in</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"\b\w{13}\b"</span>).<span class="ident">unwrap</span>().<span class="ident">find_iter</span>(<span class="ident">text</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">pos</span>);
}
<span class="comment">// Output:</span>
<span class="comment">// (0, 13)</span>
<span class="comment">// (14, 27)</span>
<span class="comment">// (28, 41)</span>
<span class="comment">// (45, 58)</span></pre>
</div><h4 id='method.captures' class="method"><span id='captures.v' class='invisible'><code>fn <a href='#method.captures' class='fnname'>captures</a><'t>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&'t [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="../../regex/bytes/struct.Captures.html" title="struct regex::bytes::Captures">Captures</a><'t>></code></span></h4>
<div class='docblock'><p>Returns the capture groups corresponding to the leftmost-first
match in <code>text</code>. Capture group <code>0</code> always corresponds to the entire
match. If no match is found, then <code>None</code> is returned.</p>
<p>You should only use <code>captures</code> if you need access to submatches.
Otherwise, <code>find</code> is faster for discovering the location of the overall
match.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Say you have some text with movie names and their release years,
like "'Citizen Kane' (1941)". It'd be nice if we could search for text
looking like that, while also extracting the movie name and its release
year separately.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"'([^']+)'\s+\((\d{4})\)"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"Not my favorite movie: 'Citizen Kane' (1941)."</span>;
<span class="kw">let</span> <span class="ident">caps</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">captures</span>(<span class="ident">text</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">1</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"Citizen Kane"</span>[..]));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"1941"</span>[..]));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">0</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"'Citizen Kane' (1941)"</span>[..]));
<span class="comment">// You can also access the groups by index using the Index notation.</span>
<span class="comment">// Note that this will panic on an invalid index.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="number">1</span>], <span class="string">b"Citizen Kane"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="number">2</span>], <span class="string">b"1941"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="number">0</span>], <span class="string">b"'Citizen Kane' (1941)"</span>);</pre>
<p>Note that the full match is at capture group <code>0</code>. Each subsequent
capture group is indexed by the order of its opening <code>(</code>.</p>
<p>We can make this example a bit clearer by using <em>named</em> capture groups:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"'(?P<title>[^']+)'\s+\((?P<year>\d{4})\)"</span>)
.<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"Not my favorite movie: 'Citizen Kane' (1941)."</span>;
<span class="kw">let</span> <span class="ident">caps</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">captures</span>(<span class="ident">text</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">name</span>(<span class="string">"title"</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"Citizen Kane"</span>[..]));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">name</span>(<span class="string">"year"</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"1941"</span>[..]));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">0</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="string">b"'Citizen Kane' (1941)"</span>[..]));
<span class="comment">// You can also access the groups by name using the Index notation.</span>
<span class="comment">// Note that this will panic on an invalid group name.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="string">"title"</span>], <span class="string">b"Citizen Kane"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="string">"year"</span>], <span class="string">b"1941"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="number">0</span>], <span class="string">b"'Citizen Kane' (1941)"</span>);
</pre>
<p>Here we name the capture groups, which we can access with the <code>name</code>
method or the <code>Index</code> notation with a <code>&str</code>. Note that the named
capture groups are still accessible with <code>at</code> or the <code>Index</code> notation
with a <code>usize</code>.</p>
<p>The <code>0</code>th capture group is always unnamed, so it must always be
accessed with <code>at(0)</code> or <code>[0]</code>.</p>
</div><h4 id='method.captures_iter' class="method"><span id='captures_iter.v' class='invisible'><code>fn <a href='#method.captures_iter' class='fnname'>captures_iter</a><'r, 't>(&'r self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&'t [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="struct" href="../../regex/bytes/struct.FindCaptures.html" title="struct regex::bytes::FindCaptures">FindCaptures</a><'r, 't></code></span></h4>
<div class='docblock'><p>Returns an iterator over all the non-overlapping capture groups matched
in <code>text</code>. This is operationally the same as <code>find_iter</code>, except it
yields information about submatches.</p>
<h1 id='example-3' class='section-header'><a href='#example-3'>Example</a></h1>
<p>We can use this to find all movie titles and their release years in
some text, where the movie is formatted like "'Title' (xxxx)":</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"'(?P<title>[^']+)'\s+\((?P<year>\d{4})\)"</span>)
.<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"'Citizen Kane' (1941), 'The Wizard of Oz' (1939), 'M' (1931)."</span>;
<span class="kw">for</span> <span class="ident">caps</span> <span class="kw">in</span> <span class="ident">re</span>.<span class="ident">captures_iter</span>(<span class="ident">text</span>) {
<span class="kw">let</span> <span class="ident">title</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="string">"title"</span>]).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">year</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="string">"year"</span>]).<span class="ident">unwrap</span>();
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Movie: {:?}, Released: {:?}"</span>, <span class="ident">title</span>, <span class="ident">year</span>);
}
<span class="comment">// Output:</span>
<span class="comment">// Movie: Citizen Kane, Released: 1941</span>
<span class="comment">// Movie: The Wizard of Oz, Released: 1939</span>
<span class="comment">// Movie: M, Released: 1931</span></pre>
</div><h4 id='method.split' class="method"><span id='split.v' class='invisible'><code>fn <a href='#method.split' class='fnname'>split</a><'r, 't>(&'r self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&'t [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="struct" href="../../regex/bytes/struct.Splits.html" title="struct regex::bytes::Splits">Splits</a><'r, 't></code></span></h4>
<div class='docblock'><p>Returns an iterator of substrings of <code>text</code> delimited by a match of the
regular expression. Namely, each element of the iterator corresponds to
text that <em>isn't</em> matched by the regular expression.</p>
<p>This method will <em>not</em> copy the text given.</p>
<h1 id='example-4' class='section-header'><a href='#example-4'>Example</a></h1>
<p>To split a string delimited by arbitrary amounts of spaces or tabs:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"[ \t]+"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">fields</span>: <span class="ident">Vec</span><span class="op"><</span><span class="kw-2">&</span>[<span class="ident">u8</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">split</span>(<span class="string">b"a b \t c\td e"</span>).<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">fields</span>, <span class="macro">vec</span><span class="macro">!</span>[
<span class="kw-2">&</span><span class="string">b"a"</span>[..], <span class="kw-2">&</span><span class="string">b"b"</span>[..], <span class="kw-2">&</span><span class="string">b"c"</span>[..], <span class="kw-2">&</span><span class="string">b"d"</span>[..], <span class="kw-2">&</span><span class="string">b"e"</span>[..],
]);</pre>
</div><h4 id='method.splitn' class="method"><span id='splitn.v' class='invisible'><code>fn <a href='#method.splitn' class='fnname'>splitn</a><'r, 't>(&'r self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&'t [</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>) -> <a class="struct" href="../../regex/bytes/struct.SplitsN.html" title="struct regex::bytes::SplitsN">SplitsN</a><'r, 't></code></span></h4>
<div class='docblock'><p>Returns an iterator of at most <code>limit</code> substrings of <code>text</code> delimited
by a match of the regular expression. (A <code>limit</code> of <code>0</code> will return no
substrings.) Namely, each element of the iterator corresponds to text
that <em>isn't</em> matched by the regular expression. The remainder of the
string that is not split will be the last element in the iterator.</p>
<p>This method will <em>not</em> copy the text given.</p>
<h1 id='example-5' class='section-header'><a href='#example-5'>Example</a></h1>
<p>Get the first two words in some text:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"\W+"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">fields</span>: <span class="ident">Vec</span><span class="op"><</span><span class="kw-2">&</span>[<span class="ident">u8</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">splitn</span>(<span class="string">b"Hey! How are you?"</span>, <span class="number">3</span>).<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">fields</span>, <span class="macro">vec</span><span class="macro">!</span>[<span class="kw-2">&</span><span class="string">b"Hey"</span>[..], <span class="kw-2">&</span><span class="string">b"How"</span>[..], <span class="kw-2">&</span><span class="string">b"are you?"</span>[..]]);</pre>
</div><h4 id='method.replace' class="method"><span id='replace.v' class='invisible'><code>fn <a href='#method.replace' class='fnname'>replace</a><R: <a class="trait" href="../../regex/bytes/trait.Replacer.html" title="trait regex::bytes::Replacer">Replacer</a>>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>, rep: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>></code></span></h4>
<div class='docblock'><p>Replaces the leftmost-first match with the replacement provided. The
replacement can be a regular byte string (where <code>$N</code> and <code>$name</code> are
expanded to match capture groups) or a function that takes the matches'
<code>Captures</code> and returns the replaced byte string.</p>
<p>If no match is found, then a copy of the byte string is returned
unchanged.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<p>Note that this function is polymorphic with respect to the replacement.
In typical usage, this can just be a normal byte string:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">"[^01]+"</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">re</span>.<span class="ident">replace</span>(<span class="string">b"1078910"</span>, <span class="kw-2">&</span><span class="string">b""</span>[..]), <span class="string">b"1010"</span>);</pre>
<p>But anything satisfying the <code>Replacer</code> trait will work. For example, a
closure of type <code>|&Captures| -> Vec<u8></code> provides direct access to the
captures corresponding to a match. This allows one to access submatches
easily:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"([^,\s]+),\s+(\S+)"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">replace</span>(<span class="string">b"Springsteen, Bruce"</span>, <span class="op">|</span><span class="ident">caps</span>: <span class="kw-2">&</span><span class="ident">Captures</span><span class="op">|</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">replacement</span> <span class="op">=</span> <span class="ident">caps</span>[<span class="number">2</span>].<span class="ident">to_owned</span>();
<span class="ident">replacement</span>.<span class="ident">push</span>(<span class="string">b' '</span>);
<span class="ident">replacement</span>.<span class="ident">extend</span>(<span class="kw-2">&</span><span class="ident">caps</span>[<span class="number">1</span>]);
<span class="ident">replacement</span>
});
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">b"Bruce Springsteen"</span>);</pre>
<p>But this is a bit cumbersome to use all the time. Instead, a simple
syntax is supported that expands <code>$name</code> into the corresponding capture
group. Here's the last example, but using this expansion technique
with named capture groups:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"(?P<last>[^,\s]+),\s+(?P<first>\S+)"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">replace</span>(<span class="string">b"Springsteen, Bruce"</span>, <span class="kw-2">&</span><span class="string">b"$first $last"</span>[..]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">b"Bruce Springsteen"</span>);</pre>
<p>Note that using <code>$2</code> instead of <code>$first</code> or <code>$1</code> instead of <code>$last</code>
would produce the same result. To write a literal <code>$</code> use <code>$$</code>.</p>
<p>If <code>$name</code> isn't a valid capture group (whether the name doesn't exist
or isn't a valid index), then it is replaced with the empty string.</p>
<p>The longest possible name is used. e.g., <code>$1a</code> looks up the capture
group named <code>1a</code> and not the capture group at index <code>1</code>. To exert more
precise control over the name, use braces, e.g., <code>${1}a</code>.</p>
<p>Finally, sometimes you just want to replace a literal string with no
submatch expansion. This can be done by wrapping a byte string with
<code>NoExpand</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">regex</span>::<span class="ident">bytes</span>::<span class="ident">NoExpand</span>;
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"(?P<last>[^,\s]+),\s+(\S+)"</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">replace</span>(<span class="string">b"Springsteen, Bruce"</span>, <span class="ident">NoExpand</span>(<span class="string">b"$2 $last"</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">b"$2 $last"</span>);</pre>
</div><h4 id='method.replace_all' class="method"><span id='replace_all.v' class='invisible'><code>fn <a href='#method.replace_all' class='fnname'>replace_all</a><R: <a class="trait" href="../../regex/bytes/trait.Replacer.html" title="trait regex::bytes::Replacer">Replacer</a>>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>, rep: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>></code></span></h4>
<div class='docblock'><p>Replaces all non-overlapping matches in <code>text</code> with the replacement
provided. This is the same as calling <code>replacen</code> with <code>limit</code> set to
<code>0</code>.</p>
<p>See the documentation for <code>replace</code> for details on how to access
submatches in the replacement text.</p>
</div><h4 id='method.replacen' class="method"><span id='replacen.v' class='invisible'><code>fn <a href='#method.replacen' class='fnname'>replacen</a><R: <a class="trait" href="../../regex/bytes/trait.Replacer.html" title="trait regex::bytes::Replacer">Replacer</a>>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, rep: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>></code></span></h4>
<div class='docblock'><p>Replaces at most <code>limit</code> non-overlapping matches in <code>text</code> with the
replacement provided. If <code>limit</code> is 0, then all non-overlapping matches
are replaced.</p>
<p>See the documentation for <code>replace</code> for details on how to access
submatches in the replacement text.</p>
</div><h4 id='method.shortest_match' class="method"><span id='shortest_match.v' class='invisible'><code>fn <a href='#method.shortest_match' class='fnname'>shortest_match</a>(&self, text: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>></code></span></h4>
<div class='docblock'><p>Returns the end location of a match in the text given.</p>
<p>This method may have the same performance characteristics as
<code>is_match</code>, except it provides an end location for a match. In
particular, the location returned <em>may be shorter</em> than the proper end
of the leftmost-first match.</p>
<h1 id='example-6' class='section-header'><a href='#example-6'>Example</a></h1>
<p>Typically, <code>a+</code> would match the entire first sequence of <code>a</code> in some
text, but <code>shortest_match</code> can give up as soon as it sees the first
<code>a</code>.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">b"aaaaa"</span>;
<span class="kw">let</span> <span class="ident">pos</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"a+"</span>).<span class="ident">unwrap</span>().<span class="ident">shortest_match</span>(<span class="ident">text</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">pos</span>, <span class="prelude-val">Some</span>(<span class="number">1</span>));</pre>
</div><h4 id='method.as_str' class="method"><span id='as_str.v' class='invisible'><code>fn <a href='#method.as_str' class='fnname'>as_str</a>(&self) -> &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a></code></span></h4>
<div class='docblock'><p>Returns the original string of this regex.</p>
</div><h4 id='method.capture_names' class="method"><span id='capture_names.v' class='invisible'><code>fn <a href='#method.capture_names' class='fnname'>capture_names</a>(&self) -> <a class="struct" href="../../regex/bytes/struct.CaptureNames.html" title="struct regex::bytes::CaptureNames">CaptureNames</a></code></span></h4>
<div class='docblock'><p>Returns an iterator over the capture names.</p>
</div><h4 id='method.captures_len' class="method"><span id='captures_len.v' class='invisible'><code>fn <a href='#method.captures_len' class='fnname'>captures_len</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></code></span></h4>
<div class='docblock'><p>Returns the number of captures.</p>
</div></div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a> for <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/regex/re_bytes.rs.html#38' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&self) -> <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span></h4>
<div class='docblock'><p>Returns a copy of the value. <a href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#tymethod.clone">Read more</a></p>
</div><h4 id='method.clone_from' class="method"><span id='clone_from.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#method.clone_from' class='fnname'>clone_from</a>(&mut self, source: &Self)</code><div class='since' title='Stable since Rust version 1.0.0'>1.0.0</div></span></h4>
<div class='docblock'><p>Performs copy-assignment from <code>source</code>. <a href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#method.clone_from">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Display.html" title="trait core::fmt::Display">Display</a> for <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/regex/re_bytes.rs.html#41-46' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Display.html#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span></h4>
<div class='docblock'><p>Shows the original regular expression.</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/regex/re_bytes.rs.html#48-53' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt-1' class="method"><span id='fmt.v-1' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span></h4>
<div class='docblock'><p>Shows the original regular expression.</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/str/trait.FromStr.html" title="trait core::str::FromStr">FromStr</a> for <a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/regex/re_bytes.rs.html#65-72' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Err' class="type"><span id='Err.t' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/str/trait.FromStr.html#associatedtype.Err' class="type">Err</a> = <a class="enum" href="../../regex/enum.Error.html" title="enum regex::Error">Error</a></code></span></h4>
<div class='docblock'><p>The associated error which can be returned from parsing.</p>
</div><h4 id='method.from_str' class="method"><span id='from_str.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/str/trait.FromStr.html#tymethod.from_str' class='fnname'>from_str</a>(s: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="struct" href="../../regex/bytes/struct.Regex.html" title="struct regex::bytes::Regex">Regex</a>, <a class="enum" href="../../regex/enum.Error.html" title="enum regex::Error">Error</a>></code></span></h4>
<div class='docblock'><p>Attempts to parse a string into a regular expression</p>
</div></div></section>
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