| <!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="Equivalent to `p1.or(p2)`."><meta name="keywords" content="rust, rustlang, rust-lang, or"><title>or in combine::parser::choice - 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="../../../combine/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="../../../combine/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 combine::parser::choice</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">combine</a>::<wbr><a href="../index.html">parser</a>::<wbr><a href="index.html">choice</a>::<wbr><a class="fn" href="#">or</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/combine/parser/choice.rs.html#624-631">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 or<Input, P1, P2>(p1: P1, p2: P2) -> <a class="struct" href="struct.Or.html" title="struct combine::parser::choice::Or">Or</a><P1, P2><span class="where fmt-newline">where<br> Input: <a class="trait" href="../../trait.Stream.html" title="trait combine::Stream">Stream</a>,<br> P1: <a class="trait" href="../../trait.Parser.html" title="trait combine::Parser">Parser</a><Input>,<br> P2: <a class="trait" href="../../trait.Parser.html" title="trait combine::Parser">Parser</a><Input, Output = P1::<a class="associatedtype" href="../../trait.Parser.html#associatedtype.Output" title="type combine::Parser::Output">Output</a>>,</span></code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Equivalent to <a href="../trait.Parser.html#method.or"><code>p1.or(p2)</code></a>.</p> |
| <p>If you are looking to chain 3 or more parsers using <code>or</code> you may consider using the |
| <a href="../../macro.choice.html"><code>choice!</code></a> macro instead, which can be clearer and may result in a faster parser.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">let </span><span class="kw-2">mut </span>parser = or( |
| string(<span class="string">"let"</span>), |
| or(digit().map(|<span class="kw">_</span>| <span class="string">"digit"</span>), string(<span class="string">"led"</span>)), |
| ); |
| <span class="macro">assert_eq!</span>(parser.parse(<span class="string">"let"</span>), <span class="prelude-val">Ok</span>((<span class="string">"let"</span>, <span class="string">""</span>))); |
| <span class="macro">assert_eq!</span>(parser.parse(<span class="string">"1"</span>), <span class="prelude-val">Ok</span>((<span class="string">"digit"</span>, <span class="string">""</span>))); |
| <span class="macro">assert!</span>(parser.parse(<span class="string">"led"</span>).is_err()); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>parser2 = or(string(<span class="string">"two"</span>), string(<span class="string">"three"</span>)); |
| <span class="comment">// Fails as the parser for "two" consumes the first 't' before failing |
| </span><span class="macro">assert!</span>(parser2.parse(<span class="string">"three"</span>).is_err()); |
| |
| <span class="comment">// Use 'attempt' to make failing parsers always act as if they have not committed any input |
| </span><span class="kw">let </span><span class="kw-2">mut </span>parser3 = or(attempt(string(<span class="string">"two"</span>)), attempt(string(<span class="string">"three"</span>))); |
| <span class="macro">assert_eq!</span>(parser3.parse(<span class="string">"three"</span>), <span class="prelude-val">Ok</span>((<span class="string">"three"</span>, <span class="string">""</span>)));</code></pre></div> |
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