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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="Returns true if the given character can be escaped in a regex."><title>is_escapeable_character in regex_syntax - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-dd39b87e5fcfba68.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="regex_syntax" data-themes="" data-resource-suffix="" data-rustdoc-version="1.80.0 (051478957 2024-07-21)" data-channel="1.80.0" data-search-js="search-d52510db62a78183.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../static.files/storage-118b08c4c78b968e.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-20a3ad099b048cf2.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-df360f571f6edeae.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.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" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../regex_syntax/index.html">regex_syntax</a><span class="version">0.8.4</span></h2></div><div class="sidebar-elems"></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="index.html">regex_syntax</a>::<wbr><a class="fn" href="#">is_escapeable_character</a><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><span class="out-of-band"><a class="src" href="../src/regex_syntax/lib.rs.html#303-331">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><code>pub fn is_escapeable_character(c: <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.char.html">char</a>) -&gt; <a class="primitive" href="https://doc.rust-lang.org/1.80.0/std/primitive.bool.html">bool</a></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Returns true if the given character can be escaped in a regex.</p>
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2024-02-13 06:38:44 +00:00
<p>This returns true in all cases that <code>is_meta_character</code> returns true, but
also returns true in some cases where <code>is_meta_character</code> returns false.
For example, <code>%</code> is not a meta character, but it is escapeable. That is,
<code>%</code> and <code>\%</code> both match a literal <code>%</code> in all contexts.</p>
<p>The purpose of this routine is to provide knowledge about what characters
may be escaped. Namely, most regex engines permit “superfluous” escapes
where characters without any special significance may be escaped even
though there is no actual <em>need</em> to do so.</p>
<p>This will return false for some characters. For example, <code>e</code> is not
escapeable. Therefore, <code>\e</code> will either result in a parse error (which is
true today), or it could backwards compatibly evolve into a new construct
with its own meaning. Indeed, that is the purpose of banning <em>some</em>
superfluous escapes: it provides a way to evolve the syntax in a compatible
manner.</p>
deploy: 39fc7f2b9fd58ce67982b1c71c788f3b031ae3df
2024-03-27 11:12:16 +00:00
<h2 id="example"><a class="doc-anchor" href="#example">§</a>Example</h2>
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2024-02-13 06:38:44 +00:00
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>regex_syntax::is_escapeable_character;
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'?'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'-'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'&amp;'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'#'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'%'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'/'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'!'</span>));
<span class="macro">assert!</span>(is_escapeable_character(<span class="string">'"'</span>));
<span class="macro">assert!</span>(!is_escapeable_character(<span class="string">'e'</span>));</code></pre></div>
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