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<h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>syn</a>::<wbr><a class="macro" href=''>reject</a></span><span class='out-of-band'><span id='render-detail'>
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<pre class="rust macro">
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<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">reject</span> {
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(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>:<span class="ident">expr</span>,) <span class="op">=></span> { ... };
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}</pre>
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<div class='docblock'><p>Unconditionally fail to parse anything.</p>
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<p>This may be useful in rejecting some arms of a <code>switch!</code> parser.</p>
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<ul>
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<li><strong>Syntax:</strong> <code>reject!()</code></li>
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<li><strong>Output:</strong> never succeeds</li>
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</ul>
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<pre class="rust rust-example-rendered">
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<span class="attribute">#[<span class="ident">macro_use</span>]</span>
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<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">syn</span>;
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<span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">Item</span>;
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<span class="comment">// Parse any item, except for a module.</span>
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<span class="macro">named</span><span class="macro">!</span>(<span class="ident">almost_any_item</span> <span class="op">-></span> <span class="ident">Item</span>,
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<span class="macro">switch</span><span class="macro">!</span>(<span class="macro">syn</span><span class="macro">!</span>(<span class="ident">Item</span>),
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<span class="ident">Item</span>::<span class="ident">Mod</span>(_) <span class="op">=></span> <span class="macro">reject</span><span class="macro">!</span>()
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<span class="op">|</span>
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<span class="ident">ok</span> <span class="op">=></span> <span class="macro">value</span><span class="macro">!</span>(<span class="ident">ok</span>)
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)
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);</pre>
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<p><em>This macro is available if Syn is built with the <code>"parsing"</code> feature.</em></p>
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