| <!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="Returns true if the given character has significance in a regex."><meta name="keywords" content="rust, rustlang, rust-lang, is_meta_character"><title>is_meta_character in regex_syntax - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../normalize.css"><link rel="stylesheet" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../ayu.css" disabled><link rel="stylesheet" href="../dark.css" disabled><link rel="stylesheet" href="../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../storage.js"></script><script defer src="sidebar-items.js"></script><script defer src="../main.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../favicon.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../regex_syntax/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../regex_syntax/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><div class="sidebar-elems"><h2><a href="index.html">In regex_syntax</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Function <a href="index.html">regex_syntax</a>::<wbr><a class="fn" href="#">is_meta_character</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/regex_syntax/lib.rs.html#255-261">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust fn"><code>pub fn is_meta_character(c: char) -> bool</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Returns true if the given character has significance in a regex.</p> |
| <p>Generally speaking, these are the only characters which <em>must</em> be escaped |
| in order to match their literal meaning. For example, to match a literal |
| <code>|</code>, one could write <code>\|</code>. Sometimes escaping isn’t always necessary. For |
| example, <code>-</code> is treated as a meta character because of its significance |
| for writing ranges inside of character classes, but the regex <code>-</code> will |
| match a literal <code>-</code> because <code>-</code> has no special meaning outside of character |
| classes.</p> |
| <p>In order to determine whether a character may be escaped at all, the |
| <a href="fn.is_escapeable_character.html" title="is_escapeable_character"><code>is_escapeable_character</code></a> routine should be used. The difference between |
| <code>is_meta_character</code> and <code>is_escapeable_character</code> is that the latter will |
| return true for some characters that are <em>not</em> meta characters. For |
| example, <code>%</code> and <code>\%</code> both match a literal <code>%</code> in all contexts. In other |
| words, <code>is_escapeable_character</code> includes “superfluous” escapes.</p> |
| <p>Note that the set of characters for which this function returns <code>true</code> or |
| <code>false</code> is fixed and won’t change in a semver compatible release. (In this |
| case, “semver compatible release” actually refers to the <code>regex</code> crate |
| itself, since reducing or expanding the set of meta characters would be a |
| breaking change for not just <code>regex-syntax</code> but also <code>regex</code> itself.)</p> |
| <h2 id="example"><a href="#example">Example</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>regex_syntax::is_meta_character; |
| |
| <span class="macro">assert!</span>(is_meta_character(<span class="string">'?'</span>)); |
| <span class="macro">assert!</span>(is_meta_character(<span class="string">'-'</span>)); |
| <span class="macro">assert!</span>(is_meta_character(<span class="string">'&'</span>)); |
| <span class="macro">assert!</span>(is_meta_character(<span class="string">'#'</span>)); |
| |
| <span class="macro">assert!</span>(!is_meta_character(<span class="string">'%'</span>)); |
| <span class="macro">assert!</span>(!is_meta_character(<span class="string">'/'</span>)); |
| <span class="macro">assert!</span>(!is_meta_character(<span class="string">'!'</span>)); |
| <span class="macro">assert!</span>(!is_meta_character(<span class="string">'"'</span>)); |
| <span class="macro">assert!</span>(!is_meta_character(<span class="string">'e'</span>));</code></pre></div> |
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