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| <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></h1><span class="out-of-band"> |
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| <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/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><div class="item-info"><div class="stab portability">This is supported on <strong>crate features <code>parsing</code> and <code>proc-macro</code></strong> only.</div></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> |
| <p><em>This function is available only if Syn is built with both the <code>"parsing"</code> and |
| <code>"proc-macro"</code> features.</em></p> |
| <h2 id="examples" class="section-header"><a href="#examples">Examples</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use</span> <span class="ident">proc_macro::TokenStream</span>; |
| <span class="kw">use</span> <span class="ident">quote::quote</span>; |
| <span class="kw">use</span> <span class="ident">syn::DeriveInput</span>; |
| |
| <span class="attribute">#[<span class="ident">proc_macro_derive</span>(<span class="ident">MyMacro</span>)]</span> |
| <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> { |
| <span class="comment">// Parse the tokens into a syntax tree</span> |
| <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>(); |
| |
| <span class="comment">// Build the output, possibly using quasi-quotation</span> |
| <span class="kw">let</span> <span class="ident">expanded</span> <span class="op">=</span> <span class="macro">quote!</span> { |
| <span class="comment">/* ... */</span> |
| }; |
| |
| <span class="comment">// Convert into a token stream and return it</span> |
| <span class="ident">expanded</span>.<span class="ident">into</span>() |
| }</code></pre></div> |
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