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<section id='main' class="content"><h1 class='fqn'><span class='in-band'>Function <a href='index.html'>combine</a>::<wbr><a class="fn" href=''>choice</a></span><span class='out-of-band'><span id='render-detail'>
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</span><a class='srclink' href='../src/combine/combinator.rs.html#753-759' title='goto source code'>[src]</a></span></h1><pre class='rust fn'>pub fn choice<S, P>(ps: S) -> <a class="struct" href="../combine/combinator/struct.Choice.html" title="struct combine::combinator::Choice">Choice</a><S, P> <span class="where fmt-newline">where<br> S: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.AsMut.html" title="trait core::convert::AsMut">AsMut</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">[</a>P<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>>,<br> P: <a class="trait" href="../combine/trait.Parser.html" title="trait combine::Parser">Parser</a>, </span></pre><div class='docblock'><p>Takes an array of parsers and tries to apply them each in order.
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Fails if all the parsers fails or if an applied parser consumes input before failing.</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">parser</span> <span class="op">=</span> <span class="ident">choice</span>([<span class="ident">string</span>(<span class="string">"Apple"</span>), <span class="ident">string</span>(<span class="string">"Banana"</span>), <span class="ident">string</span>(<span class="string">"Orange"</span>)]);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">parser</span>.<span class="ident">parse</span>(<span class="string">"Banana"</span>), <span class="prelude-val">Ok</span>((<span class="string">"Banana"</span>, <span class="string">""</span>)));
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">parser</span>.<span class="ident">parse</span>(<span class="string">"Orangexx"</span>), <span class="prelude-val">Ok</span>((<span class="string">"Orange"</span>, <span class="string">"xx"</span>)));
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<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">parser</span>.<span class="ident">parse</span>(<span class="string">"Appl"</span>).<span class="ident">is_err</span>());
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<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">parser</span>.<span class="ident">parse</span>(<span class="string">"Pear"</span>).<span class="ident">is_err</span>());
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">parser2</span> <span class="op">=</span> <span class="ident">choice</span>([<span class="ident">string</span>(<span class="string">"one"</span>), <span class="ident">string</span>(<span class="string">"two"</span>), <span class="ident">string</span>(<span class="string">"three"</span>)]);
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<span class="comment">// Fails as the parser for "two" consumes the first 't' before failing</span>
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<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">parser2</span>.<span class="ident">parse</span>(<span class="string">"three"</span>).<span class="ident">is_err</span>());
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<span class="comment">// Use 'try' to make failing parsers always act as if they have not consumed any input</span>
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">parser3</span> <span class="op">=</span> <span class="ident">choice</span>([<span class="ident">try</span>(<span class="ident">string</span>(<span class="string">"one"</span>)), <span class="ident">try</span>(<span class="ident">string</span>(<span class="string">"two"</span>)), <span class="ident">try</span>(<span class="ident">string</span>(<span class="string">"three"</span>))]);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">parser3</span>.<span class="ident">parse</span>(<span class="string">"three"</span>), <span class="prelude-val">Ok</span>((<span class="string">"three"</span>, <span class="string">""</span>)));</pre>
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