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443 lines
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<title>regex::Regex - Rust</title>
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<a href='../regex/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a>
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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></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 class="struct" href=''>Regex</a></span><span class='out-of-band'><span id='render-detail'>
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<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
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[<span class='inner'>−</span>]
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</span><a class='srclink' href='../src/regex/re_unicode.rs.html#100' title='goto source code'>[src]</a></span></h1>
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<pre class='rust struct'>pub struct Regex(_);</pre><div class='docblock'><p>A compiled regular expression for matching Unicode strings.</p>
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<p>It is represented as either a sequence of bytecode instructions (dynamic)
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or as a specialized Rust function (native). It can be used to search, split
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or replace text. All searching is done with an implicit <code>.*?</code> at the
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beginning and end of an expression. To force an expression to match the
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whole string (or a prefix or a suffix), you must use an anchor like <code>^</code> or
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<code>$</code> (or <code>\A</code> and <code>\z</code>).</p>
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<p>While this crate will handle Unicode strings (whether in the regular
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expression or in the search text), all positions returned are <strong>byte
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indices</strong>. Every byte index is guaranteed to be at a Unicode code point
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boundary.</p>
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<p>The lifetimes <code>'r</code> and <code>'t</code> in this crate correspond to the lifetime of a
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compiled regular expression and text to search, respectively.</p>
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<p>The only methods that allocate new strings are the string replacement
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methods. All other methods (searching and splitting) return borrowed
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pointers into the string given.</p>
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<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
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<p>Find the location of a US phone number:</p>
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<pre class="rust rust-example-rendered">
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<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">"[0-9]{3}-[0-9]{3}-[0-9]{4}"</span>).<span class="ident">unwrap</span>();
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">re</span>.<span class="ident">find</span>(<span class="string">"phone: 111-222-3333"</span>), <span class="prelude-val">Some</span>((<span class="number">7</span>, <span class="number">19</span>)));</pre>
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<h1 id='using-the-stdstrstrext-methods-with-regex' class='section-header'><a href='#using-the-stdstrstrext-methods-with-regex'>Using the <code>std::str::StrExt</code> methods with <code>Regex</code></a></h1>
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<blockquote>
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<p><strong>Note</strong>: This section requires that this crate is currently compiled with
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the <code>pattern</code> Cargo feature enabled.</p>
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</blockquote>
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<p>Since <code>Regex</code> implements <code>Pattern</code>, you can use regexes with methods
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defined on <code>std::str::StrExt</code>. For example, <code>is_match</code>, <code>find</code>, <code>find_iter</code>
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and <code>split</code> can be replaced with <code>StrExt::contains</code>, <code>StrExt::find</code>,
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<code>StrExt::match_indices</code> and <code>StrExt::split</code>.</p>
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<p>Here are some examples:</p>
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<pre class="rust rust-example-rendered">
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<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"\d+"</span>).<span class="ident">unwrap</span>();
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<span class="kw">let</span> <span class="ident">haystack</span> <span class="op">=</span> <span class="string">"a111b222c"</span>;
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<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">haystack</span>.<span class="ident">contains</span>(<span class="kw-2">&</span><span class="ident">re</span>));
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">haystack</span>.<span class="ident">find</span>(<span class="kw-2">&</span><span class="ident">re</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">haystack</span>.<span class="ident">match_indices</span>(<span class="kw-2">&</span><span class="ident">re</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>(),
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<span class="macro">vec</span><span class="macro">!</span>[(<span class="number">1</span>, <span class="number">4</span>), (<span class="number">5</span>, <span class="number">8</span>)]);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">haystack</span>.<span class="ident">split</span>(<span class="kw-2">&</span><span class="ident">re</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>(), <span class="macro">vec</span><span class="macro">!</span>[<span class="string">"a"</span>, <span class="string">"b"</span>, <span class="string">"c"</span>]);</pre>
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</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl <a class="struct" href="../regex/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#158-680' title='goto source code'>[src]</a></span></h3>
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<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/struct.Regex.html" title="struct regex::Regex">Regex</a>, <a class="enum" href="../regex/enum.Error.html" title="enum regex::Error">Error</a>></code></span></h4>
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<div class='docblock'><p>Compiles a regular expression. Once compiled, it can be used repeatedly
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to search, split or replace text in a string.</p>
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<p>If an invalid expression is given, then an error is returned.</p>
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</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/struct.Regex.html" title="struct regex::Regex">Regex</a>, <a class="enum" href="../regex/enum.Error.html" title="enum regex::Error">Error</a>></code></span></h4>
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<div class='docblock'><p>Compiles a regular expression with the given size limit.</p>
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<p>The size limit is applied to the size of the <em>compiled</em> data structure.
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If the data structure exceeds the size given, then an error is
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returned.</p>
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</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.str.html">str</a>) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></h4>
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<div class='docblock'><p>Returns true if and only if the regex matches the string given.</p>
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<p>It is recommended to use this method if all you need to do is test
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a match, since the underlying matching engine may be able to do less
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work.</p>
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<h1 id='example' class='section-header'><a href='#example'>Example</a></h1>
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<p>Test if some text contains at least one word with exactly 13
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Unicode word characters:</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">"I categorically deny having triskaidekaphobia."</span>;
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<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>
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</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.str.html">str</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>
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<div class='docblock'><p>Returns the start and end byte range of the leftmost-first match in
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<code>text</code>. If no match exists, then <code>None</code> is returned.</p>
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<p>Note that this should only be used if you want to discover the position
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of the match. Testing the existence of a match is faster if you use
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<code>is_match</code>.</p>
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<h1 id='example-1' class='section-header'><a href='#example-1'>Example</a></h1>
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<p>Find the start and end location of the first word with exactly 13
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Unicode word characters:</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">"I categorically deny having triskaidekaphobia."</span>;
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<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>);
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<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>
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</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: &'t <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="struct" href="../regex/struct.FindMatches.html" title="struct regex::FindMatches">FindMatches</a><'r, 't></code></span></h4>
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<div class='docblock'><p>Returns an iterator for each successive non-overlapping match in
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<code>text</code>, returning the start and end byte indices with respect to
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<code>text</code>.</p>
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<h1 id='example-2' class='section-header'><a href='#example-2'>Example</a></h1>
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<p>Find the start and end location of every word with exactly 13 Unicode
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word characters:</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">"Retroactively relinquishing remunerations is reprehensible."</span>;
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<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>) {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">pos</span>);
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}
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<span class="comment">// Output:</span>
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<span class="comment">// (0, 13)</span>
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<span class="comment">// (14, 27)</span>
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<span class="comment">// (28, 41)</span>
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<span class="comment">// (45, 58)</span></pre>
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</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: &'t <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/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="../regex/struct.Captures.html" title="struct regex::Captures">Captures</a><'t>></code></span></h4>
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<div class='docblock'><p>Returns the capture groups corresponding to the leftmost-first
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match in <code>text</code>. Capture group <code>0</code> always corresponds to the entire
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match. If no match is found, then <code>None</code> is returned.</p>
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<p>You should only use <code>captures</code> if you need access to submatches.
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Otherwise, <code>find</code> is faster for discovering the location of the overall
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match.</p>
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<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
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<p>Say you have some text with movie names and their release years,
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like "'Citizen Kane' (1941)". It'd be nice if we could search for text
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looking like that, while also extracting the movie name and its release
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year separately.</p>
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<pre class="rust rust-example-rendered">
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<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>();
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<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">"Not my favorite movie: 'Citizen Kane' (1941)."</span>;
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<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>();
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<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="string">"Citizen Kane"</span>));
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<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="string">"1941"</span>));
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<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="string">"'Citizen Kane' (1941)"</span>));
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<span class="comment">// You can also access the groups by index using the Index notation.</span>
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<span class="comment">// Note that this will panic on an invalid index.</span>
|
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<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">"Citizen Kane"</span>);
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<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">"1941"</span>);
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<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">"'Citizen Kane' (1941)"</span>);</pre>
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<p>Note that the full match is at capture group <code>0</code>. Each subsequent
|
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capture group is indexed by the order of its opening <code>(</code>.</p>
|
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<p>We can make this example a bit clearer by using <em>named</em> capture groups:</p>
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<pre class="rust rust-example-rendered">
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<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>)
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.<span class="ident">unwrap</span>();
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<span class="kw">let</span> <span class="ident">text</span> <span class="op">=</span> <span class="string">"Not my favorite movie: 'Citizen Kane' (1941)."</span>;
|
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<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>();
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<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="string">"Citizen Kane"</span>));
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<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="string">"1941"</span>));
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<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="string">"'Citizen Kane' (1941)"</span>));
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<span class="comment">// You can also access the groups by name using the Index notation.</span>
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<span class="comment">// Note that this will panic on an invalid group name.</span>
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<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">"Citizen Kane"</span>);
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<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">"1941"</span>);
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<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">"'Citizen Kane' (1941)"</span>);
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</pre>
|
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<p>Here we name the capture groups, which we can access with the <code>name</code>
|
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method or the <code>Index</code> notation with a <code>&str</code>. Note that the named
|
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capture groups are still accessible with <code>at</code> or the <code>Index</code> notation
|
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with a <code>usize</code>.</p>
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<p>The <code>0</code>th capture group is always unnamed, so it must always be
|
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accessed with <code>at(0)</code> or <code>[0]</code>.</p>
|
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</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: &'t <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="struct" href="../regex/struct.FindCaptures.html" title="struct regex::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">"'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="macro">println</span><span class="macro">!</span>(<span class="string">"Movie: {:?}, Released: {:?}"</span>,
|
||
<span class="ident">caps</span>.<span class="ident">name</span>(<span class="string">"title"</span>), <span class="ident">caps</span>.<span class="ident">name</span>(<span class="string">"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: &'t <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>) -> <a class="struct" href="../regex/struct.RegexSplits.html" title="struct regex::RegexSplits">RegexSplits</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">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">split</span>(<span class="string">"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="string">"a"</span>, <span class="string">"b"</span>, <span class="string">"c"</span>, <span class="string">"d"</span>, <span class="string">"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: &'t <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>) -> <a class="struct" href="../regex/struct.RegexSplitsN.html" title="struct regex::RegexSplitsN">RegexSplitsN</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">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">splitn</span>(<span class="string">"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="string">"Hey"</span>, <span class="string">"How"</span>, <span class="string">"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/trait.Replacer.html" title="trait regex::Replacer">Replacer</a>>(&self, text: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>, rep: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html" title="struct alloc::string::String">String</a></code></span></h4>
|
||
<div class='docblock'><p>Replaces the leftmost-first match with the replacement provided.
|
||
The replacement can be a regular 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 string.</p>
|
||
|
||
<p>If no match is found, then a copy of the string is returned unchanged.</p>
|
||
|
||
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
|
||
<p>Note that this function is polymorphic with respect to the replacement.
|
||
In typical usage, this can just be a normal 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">"1078910"</span>, <span class="string">""</span>), <span class="string">"1010"</span>);</pre>
|
||
|
||
<p>But anything satisfying the <code>Replacer</code> trait will work. For example,
|
||
a closure of type <code>|&Captures| -> String</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">"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="macro">format</span><span class="macro">!</span>(<span class="string">"{} {}"</span>, <span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">2</span>).<span class="ident">unwrap_or</span>(<span class="string">""</span>), <span class="ident">caps</span>.<span class="ident">at</span>(<span class="number">1</span>).<span class="ident">unwrap_or</span>(<span class="string">""</span>))
|
||
});
|
||
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">"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>$name</code> into the corresponding capture
|
||
group. Here's the last example, but using this expansion technique
|
||
with named capture groups:</p>
|
||
|
||
<pre class="rust rust-example-rendered">
|
||
<span class="kw">let</span> <span class="ident">re</span> <span class="op">=</span> <span class="ident">Regex</span>::<span class="ident">new</span>(<span class="string">r"(?P<last>[^,\s]+),\s+(?P<first>\S+)"</span>).<span class="ident">unwrap</span>();
|
||
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">re</span>.<span class="ident">replace</span>(<span class="string">"Springsteen, Bruce"</span>, <span class="string">"$first $last"</span>);
|
||
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">"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>Finally, sometimes you just want to replace a literal string with no
|
||
submatch expansion. This can be done by wrapping a 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">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">"Springsteen, Bruce"</span>, <span class="ident">NoExpand</span>(<span class="string">"$2 $last"</span>));
|
||
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="string">"$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/trait.Replacer.html" title="trait regex::Replacer">Replacer</a>>(&self, text: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>, rep: R) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html" title="struct alloc::string::String">String</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 string.</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/trait.Replacer.html" title="trait regex::Replacer">Replacer</a>>(&self, text: &<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</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/string/struct.String.html" title="struct alloc::string::String">String</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 string.</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.str.html">str</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">"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/struct.CaptureNames.html" title="struct regex::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/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#99' 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/struct.Regex.html" title="struct regex::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/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#116-121' 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/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#123-128' 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/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a> for <a class="struct" href="../regex/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#141-145' title='goto source code'>[src]</a></span></h3>
|
||
<div class='docblock'><p>Equality comparison is based on the original string. It is possible that
|
||
different regular expressions have the same matching behavior, but are
|
||
still compared unequal. For example, <code>\d+</code> and <code>\d\d*</code> match the same set
|
||
of strings, but are not considered equal.</p>
|
||
</div><div class='impl-items'><h4 id='method.eq' class="method"><span id='eq.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq' class='fnname'>eq</a>(&self, other: &<a class="struct" href="../regex/struct.Regex.html" title="struct regex::Regex">Regex</a>) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></h4>
|
||
<div class='docblock'><p>This method tests for <code>self</code> and <code>other</code> values to be equal, and is used by <code>==</code>. <a href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq">Read more</a></p>
|
||
</div><h4 id='method.ne' class="method"><span id='ne.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#method.ne' class='fnname'>ne</a>(&self, other: &Rhs) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code><div class='since' title='Stable since Rust version 1.0.0'>1.0.0</div></span></h4>
|
||
<div class='docblock'><p>This method tests for <code>!=</code>.</p>
|
||
</div></div><h3 class='impl'><span class='in-band'><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a> for <a class="struct" href="../regex/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#147' title='goto source code'>[src]</a></span></h3>
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<div class='impl-items'></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/struct.Regex.html" title="struct regex::Regex">Regex</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/regex/re_unicode.rs.html#149-156' title='goto source code'>[src]</a></span></h3>
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<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>
|
||
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|
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<div class='docblock'><p>Attempts to parse a string into a regular expression</p>
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