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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="Parse tokens of source code into the chosen syntax tree node."><title>parse in syn - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="syn" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><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">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../syn/index.html">syn</a><span class="version">2.0.52</span></h2></div><div class="sidebar-elems"></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../syn/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="index.html">syn</a>::<wbr><a class="fn" href="#">parse</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../src/syn/lib.rs.html#896-898">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><pre class="rust item-decl"><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/1.76.0/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><details class="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>
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<p>This is preferred over parsing a string because tokens are able to preserve
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information about where in the user’s code they were originally written (the
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“span” of the token), possibly allowing the compiler to produce better error
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messages.</p>
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<p>This function parses a <code>proc_macro::TokenStream</code> which is the type used for
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interop with the compiler in a procedural macro. To parse a
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<code>proc_macro2::TokenStream</code>, use <a href="fn.parse2.html" title="fn syn::parse2"><code>syn::parse2</code></a> instead.</p>
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<h2 id="examples"><a href="#examples">Examples</a></h2>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>proc_macro::TokenStream;
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<span class="kw">use </span>quote::quote;
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<span class="kw">use </span>syn::DeriveInput;
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<span class="attr">#[proc_macro_derive(MyMacro)]
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</span><span class="kw">pub fn </span>my_macro(input: TokenStream) -> TokenStream {
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<span class="comment">// Parse the tokens into a syntax tree
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</span><span class="kw">let </span>ast: DeriveInput = syn::parse(input).unwrap();
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<span class="comment">// Build the output, possibly using quasi-quotation
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</span><span class="kw">let </span>expanded = <span class="macro">quote! </span>{
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<span class="comment">/* ... */
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</span>};
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<span class="comment">// Convert into a token stream and return it
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</span>expanded.into()
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}</code></pre></div>
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</div></details></section></div></main></body></html> |