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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `whitespace` mod in crate `nom`."><meta name="keywords" content="rust, rustlang, rust-lang, whitespace"><title>nom::whitespace - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut icon" href="../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../nom/index.html'><div class='logo-container'><img src='../../rust-logo.png' alt='logo'></div></a><p class='location'>Module whitespace</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#functions">Functions</a></li></ul></div><p class='location'><a href='../index.html'>nom</a></p><script>window.sidebarCurrent = {name: 'whitespace', ty: 'mod', relpath: '../'};</script><script defer src="../sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><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/nom/whitespace.rs.html#1-1197' title='goto source code'>[src]</a></span><span class='in-band'>Module <a href='../index.html'>nom</a>::<wbr><a class="mod" href=''>whitespace</a></span></h1><div class='docblock'><p>Support for whitespace delimited formats</p>
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<p>a lot of textual formats allows spaces and other
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types of separators between tokens. Handling it
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manually with nom means wrapping all parsers
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like this:</p>
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<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered ignore">
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<span class="macro">named</span><span class="macro">!</span>(<span class="ident">token</span>, <span class="macro">delimited</span><span class="macro">!</span>(<span class="ident">space</span>, <span class="ident">tk</span>, <span class="ident">space</span>));</pre></div>
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<p>To ease the development of such parsers, you
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can use the whitespace parsing facility, which works
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as follows:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="macro">named</span><span class="macro">!</span>(<span class="ident">tuple</span><span class="op"><</span><span class="kw-2">&</span>[<span class="ident">u8</span>], (<span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">></span>,
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<span class="macro">ws</span><span class="macro">!</span>(<span class="macro">tuple</span><span class="macro">!</span>( <span class="macro">take</span><span class="macro">!</span>(<span class="number">3</span>), <span class="macro">tag</span><span class="macro">!</span>(<span class="string">"de"</span>) ))
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);
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<span class="macro">assert_eq</span><span class="macro">!</span>(
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<span class="ident">tuple</span>(<span class="kw-2">&</span><span class="string">b" \t abc de fg"</span>[..]),
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<span class="prelude-val">Ok</span>((<span class="kw-2">&</span><span class="string">b"fg"</span>[..], (<span class="kw-2">&</span><span class="string">b"abc"</span>[..], <span class="kw-2">&</span><span class="string">b"de"</span>[..])))
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);</pre></div>
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<p>The <code>ws!</code> combinator will modify the parser to
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intersperse space parsers everywhere. By default,
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it will consume the following characters: <code>" \t\r\n"</code>.</p>
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<p>If you want to modify that behaviour, you can make
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your own whitespace wrapper. As an example, if
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you don't want to consume ends of lines, only
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spaces and tabs, you can do it like this:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="macro">named</span><span class="macro">!</span>(<span class="kw">pub</span> <span class="ident">space</span>, <span class="macro">eat_separator</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="string">b" \t"</span>[..]));
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<span class="attribute">#[<span class="ident">macro_export</span>]</span>
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<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">sp</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">args</span>:<span class="ident">tt</span>)<span class="kw-2">*</span>) <span class="op">=</span><span class="op">></span> (
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{
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<span class="kw">use</span> <span class="ident">nom</span>::<span class="ident">Convert</span>;
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<span class="kw">use</span> <span class="ident">nom</span>::<span class="prelude-val">Err</span>;
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<span class="kw">match</span> <span class="macro">sep</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>, <span class="ident">space</span>, $(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">args</span>)<span class="kw-2">*</span>) {
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<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Err</span>(<span class="ident">e</span>),
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<span class="prelude-val">Ok</span>((<span class="ident">i1</span>,<span class="ident">o</span>)) <span class="op">=</span><span class="op">></span> {
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<span class="kw">match</span> <span class="ident">space</span>(<span class="ident">i1</span>) {
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<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Err</span>(<span class="prelude-val">Err</span>::<span class="ident">convert</span>(<span class="ident">e</span>)),
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<span class="prelude-val">Ok</span>((<span class="ident">i2</span>,<span class="kw">_</span>)) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Ok</span>((<span class="ident">i2</span>, <span class="ident">o</span>))
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}
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}
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}
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}
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)
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);
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<span class="macro">named</span><span class="macro">!</span>(<span class="ident">tuple</span><span class="op"><</span><span class="kw-2">&</span>[<span class="ident">u8</span>], (<span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">></span>,
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<span class="macro">sp</span><span class="macro">!</span>(<span class="macro">tuple</span><span class="macro">!</span>( <span class="macro">take</span><span class="macro">!</span>(<span class="number">3</span>), <span class="macro">tag</span><span class="macro">!</span>(<span class="string">"de"</span>) ))
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);
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<span class="macro">assert_eq</span><span class="macro">!</span>(
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<span class="ident">tuple</span>(<span class="kw-2">&</span><span class="string">b" \t abc de fg"</span>[..]),
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<span class="prelude-val">Ok</span>((<span class="kw-2">&</span><span class="string">b"fg"</span>[..], (<span class="kw-2">&</span><span class="string">b"abc"</span>[..], <span class="kw-2">&</span><span class="string">b"de"</span>[..])))
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);</pre></div>
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<p>This combinator works by replacing each combinator with
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a version that supports wrapping with separator parsers.
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It will not support the combinators you wrote in your
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own code. You can still manually wrap them with the separator
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you want, or you can copy the macros defined in src/whitespace.rs
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and modify them to support a new combinator:</p>
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<ul>
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<li>copy the combinator's code here, add the _sep suffix</li>
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<li>add the <code>$separator:expr</code> as second argument</li>
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<li>wrap any sub parsers with sep!($separator, $submac!($($args)*))</li>
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<li>reference it in the definition of <code>sep!</code> as follows:</li>
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</ul>
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<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered ignore">
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(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">separator</span>:<span class="ident">path</span>, <span class="ident">my_combinator</span> <span class="op">!</span> ($(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">rest</span>:<span class="ident">tt</span>)<span class="kw-2">*</span>) ) <span class="op">=</span><span class="op">></span> {
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<span class="macro">wrap_sep</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">i</span>,
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<span class="macro-nonterminal">$</span><span class="macro-nonterminal">separator</span>,
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<span class="macro">my_combinator_sep</span><span class="macro">!</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">separator</span>, $(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">rest</span>)<span class="kw-2">*</span>)
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)
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};</pre></div>
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</div><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
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<table><tr class='module-item'><td><a class="fn" href="fn.sp.html" title='nom::whitespace::sp fn'>sp</a></td><td class='docblock-short'></td></tr></table></section><section id="search" class="content hidden"></section><section class="footer"></section><script>window.rootPath = "../../";window.currentCrate = "nom";</script><script src="../../aliases.js"></script><script src="../../main.js"></script><script defer src="../../search-index.js"></script></body></html> |