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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><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="syn" 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="../syn/index.html">syn</a><span class="version">2.0.72</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">syn</a>::<wbr><a class="fn" href="#">parse</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/syn/lib.rs.html#914-916">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/1.80.0/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 class="doc-anchor" href="#examples">§</a>Examples</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> |