| <!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="Parse tokens of source code into the chosen syntax tree node."><meta name="keywords" content="rust, rustlang, rust-lang, parse"><title>parse in syn - 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="../syn/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="../syn/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 syn</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">syn</a>::<wbr><a class="fn" href="#">parse</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/syn/lib.rs.html#858-860">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 parse<T: <a class="trait" href="parse/trait.Parse.html" title="trait syn::parse::Parse">Parse</a>>(tokens: <a class="struct" href="https://doc.rust-lang.org/nightly/proc_macro/struct.TokenStream.html" title="struct proc_macro::TokenStream">TokenStream</a>) -> <a class="type" href="parse/type.Result.html" title="type syn::parse::Result">Result</a><T></code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Parse tokens of source code into the chosen syntax tree node.</p> |
| <p>This is preferred over parsing a string because tokens are able to preserve |
| information about where in the user’s code they were originally written (the |
| “span” of the token), possibly allowing the compiler to produce better error |
| messages.</p> |
| <p>This function parses a <code>proc_macro::TokenStream</code> which is the type used for |
| interop with the compiler in a procedural macro. To parse a |
| <code>proc_macro2::TokenStream</code>, use <a href="fn.parse2.html"><code>syn::parse2</code></a> instead.</p> |
| <h2 id="examples"><a href="#examples">Examples</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>proc_macro::TokenStream; |
| <span class="kw">use </span>quote::quote; |
| <span class="kw">use </span>syn::DeriveInput; |
| |
| <span class="attribute">#[proc_macro_derive(MyMacro)] |
| </span><span class="kw">pub fn </span>my_macro(input: TokenStream) -> TokenStream { |
| <span class="comment">// Parse the tokens into a syntax tree |
| </span><span class="kw">let </span>ast: DeriveInput = syn::parse(input).unwrap(); |
| |
| <span class="comment">// Build the output, possibly using quasi-quotation |
| </span><span class="kw">let </span>expanded = <span class="macro">quote! </span>{ |
| <span class="comment">/* ... */ |
| </span>}; |
| |
| <span class="comment">// Convert into a token stream and return it |
| </span>expanded.into() |
| }</code></pre></div> |
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