148 lines
7.1 KiB
HTML
148 lines
7.1 KiB
HTML
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<!DOCTYPE html>
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<meta name="generator" content="rustdoc">
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<meta name="description" content="API documentation for the Rust `peek` macro in crate `synom`.">
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<meta name="keywords" content="rust, rustlang, rust-lang, peek">
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<title>synom::peek - Rust</title>
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<!--[if lte IE 8]>
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This old browser is unsupported and will most likely display funky
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things.
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<![endif]-->
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<nav class="sidebar">
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<p class='location'><a href='index.html'>synom</a></p><script>window.sidebarCurrent = {name: 'peek', ty: 'macro', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<section id='main' class="content">
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<h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>synom</a>::<wbr><a class="macro" href=''>peek</a></span><span class='out-of-band'><span id='render-detail'>
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[<span class='inner'>−</span>]
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</a>
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</span><a class='srclink' href='../src/synom/lib.rs.html#625-636' title='goto source code'>[src]</a></span></h1>
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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">peek</span> {
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(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">submac</span>:<span class="macro">ident</span><span class="macro">!</span>( $(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">args</span>:<span class="ident">tt</span>)<span class="op">*</span> )) <span class="op">=></span> { ... };
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(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">f</span>:<span class="ident">expr</span>) <span class="op">=></span> { ... };
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}</pre>
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<div class='docblock'><p>Parse a value without consuming it from the input data.</p>
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<ul>
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<li><strong>Syntax:</strong> <code>peek!(THING)</code></li>
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<li><strong>Output:</strong> <code>THING</code></li>
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</ul>
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<pre class="rust rust-example-rendered">
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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="attribute">#[<span class="ident">macro_use</span>]</span> <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">synom</span>;
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<span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">Expr</span>;
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<span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">parse</span>::{<span class="ident">ident</span>, <span class="ident">expr</span>};
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<span class="kw">use</span> <span class="ident">synom</span>::<span class="ident">IResult</span>;
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<span class="comment">// Parse an expression that begins with an identifier.</span>
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<span class="macro">named</span><span class="macro">!</span>(<span class="ident">ident_expr</span> <span class="op">-></span> <span class="ident">Expr</span>,
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<span class="macro">preceded</span><span class="macro">!</span>(<span class="macro">peek</span><span class="macro">!</span>(<span class="ident">ident</span>), <span class="ident">expr</span>)
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);
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<span class="kw">fn</span> <span class="ident">main</span>() {
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<span class="comment">// begins with an identifier</span>
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<span class="kw">let</span> <span class="ident">input</span> <span class="op">=</span> <span class="string">"banana + 1"</span>;
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<span class="kw">let</span> <span class="ident">parsed</span> <span class="op">=</span> <span class="ident">ident_expr</span>(<span class="ident">input</span>).<span class="ident">expect</span>(<span class="string">"ident"</span>);
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">parsed</span>);
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<span class="comment">// does not begin with an identifier</span>
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<span class="kw">let</span> <span class="ident">input</span> <span class="op">=</span> <span class="string">"1 + banana"</span>;
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<span class="kw">let</span> <span class="ident">err</span> <span class="op">=</span> <span class="ident">ident_expr</span>(<span class="ident">input</span>);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">err</span>, <span class="ident">IResult</span>::<span class="ident">Error</span>);
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}</pre>
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</div></section>
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window.rootPath = "../";
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window.currentCrate = "synom";
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