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  1. <!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="API documentation for the Rust `parse_quote` macro in crate `syn`."><meta name="keywords" content="rust, rustlang, rust-lang, parse_quote"><title>syn::parse_quote - Rust</title><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="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script></head><body class="rustdoc macro"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><div class="sidebar-elems"><p class='location'><a href='index.html'>syn</a></p><script>window.sidebarCurrent = {name: 'parse_quote', ty: 'macro', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>syn</a>::<wbr><a class="macro" href=''>parse_quote</a></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'>&#x2212;</span>]</a></span><a class='srclink' href='../src/syn/parse_quote.rs.html#82-86' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class="rust macro">
    2. 

  2. <span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">parse_quote</span> {
    3. 

  3.     ($(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">tt</span>:<span class="ident">tt</span>)<span class="kw-2">*</span>) <span class="op">=&gt;</span> { ... };
    4. 

  4. }</pre>
    5. 

  5. </div><div class='docblock'><p>Quasi-quotation macro that accepts input like the <a href="https://docs.rs/quote/0.4/quote/index.html"><code>quote!</code></a> macro but uses
    6. 

  6. type inference to figure out a return type for those tokens.</p>
    7. 

  7. <p>The return type can be any syntax tree node that implements the <a href="synom/trait.Synom.html"><code>Synom</code></a>
    8. 

  8. trait.</p>
    9. 

  9. 

  10. <pre class="rust rust-example-rendered">
    11. 

  11. <span class="attribute">#[<span class="ident">macro_use</span>]</span>
    12. 

  12. <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">syn</span>;
    13. 

  13. 

  14. <span class="attribute">#[<span class="ident">macro_use</span>]</span>
    15. 

  15. <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">quote</span>;
    16. 

  16. 

  17. <span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">Stmt</span>;
    18. 

  18. 

  19. <span class="kw">fn</span> <span class="ident">main</span>() {
    20. 

  20.     <span class="kw">let</span> <span class="ident">name</span> <span class="op">=</span> <span class="macro">quote</span><span class="macro">!</span>(<span class="ident">v</span>);
    21. 

  21.     <span class="kw">let</span> <span class="ident">ty</span> <span class="op">=</span> <span class="macro">quote</span><span class="macro">!</span>(<span class="ident">u8</span>);
    22. 

  22. 

  23.     <span class="kw">let</span> <span class="ident">stmt</span>: <span class="ident">Stmt</span> <span class="op">=</span> <span class="macro">parse_quote</span><span class="macro">!</span> {
    24. 

  24.         <span class="kw">let</span> #<span class="ident">name</span>: #<span class="ident">ty</span> <span class="op">=</span> <span class="ident">Default</span>::<span class="ident">default</span>();
    25. 

  25.     };
    26. 

  26. 

  27.     <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{:#?}&quot;</span>, <span class="ident">stmt</span>);
    28. 

  28. }</pre>
    29. 

  29. <p><em>This macro is available if Syn is built with the <code>&quot;parsing&quot;</code> feature,
    30. 

  30. although interpolation of syntax tree nodes into the quoted tokens is only
    31. 

  31. supported if Syn is built with the <code>&quot;printing&quot;</code> feature as well.</em></p>
    32. 

  32. <h1 id="example" class="section-header"><a href="#example">Example</a></h1>
    33. 

  33. <p>The following helper function adds a bound <code>T: HeapSize</code> to every type
    34. 

  34. parameter <code>T</code> in the input generics.</p>
    35. 

  35. 

  36. <pre class="rust rust-example-rendered">
    37. 

  37. <span class="comment">// Add a bound `T: HeapSize` to every type parameter T.</span>
    38. 

  38. <span class="kw">fn</span> <span class="ident">add_trait_bounds</span>(<span class="kw-2">mut</span> <span class="ident">generics</span>: <span class="ident">Generics</span>) <span class="op">-&gt;</span> <span class="ident">Generics</span> {
    39. 

  39.     <span class="kw">for</span> <span class="ident">param</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">generics</span>.<span class="ident">params</span> {
    40. 

  40.         <span class="kw">if</span> <span class="kw">let</span> <span class="ident">GenericParam</span>::<span class="ident">Type</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">type_param</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="ident">param</span> {
    41. 

  41.             <span class="ident">type_param</span>.<span class="ident">bounds</span>.<span class="ident">push</span>(<span class="macro">parse_quote</span><span class="macro">!</span>(<span class="ident">HeapSize</span>));
    42. 

  42.         }
    43. 

  43.     }
    44. 

  44.     <span class="ident">generics</span>
    45. 

  45. }</pre>
    46. 

  46. <h1 id="special-cases" class="section-header"><a href="#special-cases">Special cases</a></h1>
    47. 

  47. <p>This macro can parse the following additional types as a special case even
    48. 

  48. though they do not implement the <code>Synom</code> trait.</p>
    49. 

  49. <ul>
    50. 

  50. <li><a href="struct.Attribute.html"><code>Attribute</code></a> — parses one attribute, allowing either outer like <code>#[...]</code>
    51. 

  51. or inner like <code>#![...]</code></li>
    52. 

  52. <li><a href="punctuated/struct.Punctuated.html"><code>Punctuated&lt;T, P&gt;</code></a> — parses zero or more <code>T</code> separated by punctuation
    53. 

  53. <code>P</code> with optional trailing punctuation</li>
    54. 

  54. </ul>
    55. 

  55. <h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1>
    56. 

  56. <p>Panics if the tokens fail to parse as the expected syntax tree type. The
    57. 

  57. caller is responsible for ensuring that the input tokens are syntactically
    58. 

  58. valid.</p>
    59. 

  59. </div></section><section id="search" class="content hidden"></section><section class="footer"></section><aside id="help" class="hidden"><div><h1 class="hidden">Help</h1><div class="shortcuts"><h2>Keyboard Shortcuts</h2><dl><dt><kbd>?</kbd></dt><dd>Show this help dialog</dd><dt><kbd>S</kbd></dt><dd>Focus the search field</dd><dt><kbd>↑</kbd></dt><dd>Move up in search results</dd><dt><kbd>↓</kbd></dt><dd>Move down in search results</dd><dt><kbd>↹</kbd></dt><dd>Switch tab</dd><dt><kbd>&#9166;</kbd></dt><dd>Go to active search result</dd><dt><kbd>+</kbd></dt><dd>Expand all sections</dd><dt><kbd>-</kbd></dt><dd>Collapse all sections</dd></dl></div><div class="infos"><h2>Search Tricks</h2><p>Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type.</p><p>Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>.</p><p>Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>)</p><p>Search multiple things at once by splitting your query with comma (e.g. <code>str,u8</code> or <code>String,struct:Vec,test</code>)</p></div></div></aside><script>window.rootPath = "../";window.currentCrate = "syn";</script><script src="../aliases.js"></script><script src="../main.js"></script><script defer src="../search-index.js"></script></body></html>
    60.