32 lines
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32 lines
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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."><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" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../dark.css" disabled><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../storage.js"></script><script src="../crates.js"></script><script defer src="../main.js"></script>
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</a><div class="sidebar-elems"><h2 class="location">Other items in<br><a href="index.html">syn</a></h2><div id="sidebar-vars" data-name="parse" data-ty="fn" data-relpath=""></div><script defer src="sidebar-items.js"></script></div></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../syn/index.html"><img class="rust-logo" src="../rust-logo.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><button type="button" id="help-button" title="help">?</button><a id="settings-menu" href="../settings.html" title="settings"><img width="18" height="18" alt="Change settings" src="../wheel.svg"></a></div></form></nav></div><section id="main-content" class="content"><h1 class="fqn"><span class="in-band">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></span><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../src/syn/lib.rs.html#895-897" title="goto source code">[src]</a></span></h1><div class="docblock 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/1.59.0/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></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>
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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"><code>syn::parse2</code></a> instead.</p>
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<p><em>This function is available only if Syn is built with both the <code>"parsing"</code> and
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<code>"proc-macro"</code> features.</em></p>
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<h2 id="examples" class="section-header"><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> <span class="ident">proc_macro::TokenStream</span>;
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<span class="kw">use</span> <span class="ident">quote::quote</span>;
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<span class="kw">use</span> <span class="ident">syn::DeriveInput</span>;
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<span class="attribute">#[<span class="ident">proc_macro_derive</span>(<span class="ident">MyMacro</span>)]</span>
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<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">my_macro</span>(<span class="ident">input</span>: <span class="ident">TokenStream</span>) -> <span class="ident">TokenStream</span> {
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<span class="comment">// Parse the tokens into a syntax tree</span>
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<span class="kw">let</span> <span class="ident">ast</span>: <span class="ident">DeriveInput</span> <span class="op">=</span> <span class="ident">syn::parse</span>(<span class="ident">input</span>).<span class="ident">unwrap</span>();
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<span class="comment">// Build the output, possibly using quasi-quotation</span>
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<span class="kw">let</span> <span class="ident">expanded</span> <span class="op">=</span> <span class="macro">quote!</span> {
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<span class="comment">/* ... */</span>
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};
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<span class="comment">// Convert into a token stream and return it</span>
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<span class="ident">expanded</span>.<span class="ident">into</span>()
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}</code></pre></div>
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