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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 `quote` crate."><meta name="keywords" content="rust, rustlang, rust-lang, quote"><title>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 mod"><!--[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><p class='location'>Crate quote</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#macros">Macros</a></li><li><a href="#traits">Traits</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'quote', ty: 'mod', relpath: '../'};</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'>Crate <a class="mod" href=''>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/quote/lib.rs.html#1-858' title='goto source code'>[src]</a></span></h1><div class='docblock'><p>This crate provides the <a href="macro.quote.html"><code>quote!</code></a> macro for turning Rust syntax tree data
  2. structures into tokens of source code.</p>
  3. <p>Procedural macros in Rust receive a stream of tokens as input, execute
  4. arbitrary Rust code to determine how to manipulate those tokens, and produce
  5. a stream of tokens to hand back to the compiler to compile into the caller's
  6. crate. Quasi-quoting is a solution to one piece of that -- producing tokens
  7. to return to the compiler.</p>
  8. <p>The idea of quasi-quoting is that we write <em>code</em> that we treat as <em>data</em>.
  9. Within the <code>quote!</code> macro, we can write what looks like code to our text
  10. editor or IDE. We get all the benefits of the editor's brace matching,
  11. syntax highlighting, indentation, and maybe autocompletion. But rather than
  12. compiling that as code into the current crate, we can treat it as data, pass
  13. it around, mutate it, and eventually hand it back to the compiler as tokens
  14. to compile into the macro caller's crate.</p>
  15. <p>This crate is motivated by the procedural macro use case, but is a
  16. general-purpose Rust quasi-quoting library and is not specific to procedural
  17. macros.</p>
  18. <p><em>Version requirement: Quote supports any compiler version back to Rust's
  19. very first support for procedural macros in Rust 1.15.0.</em></p>
  20. <pre><code class="language-toml">[dependencies]
  21. quote = &quot;0.6&quot;
  22. </code></pre>
  23. <pre class="rust rust-example-rendered">
  24. <span class="attribute">#[<span class="ident">macro_use</span>]</span>
  25. <span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">quote</span>;</pre>
  26. <h1 id="example" class="section-header"><a href="#example">Example</a></h1>
  27. <p>The following quasi-quoted block of code is something you might find in <a href="https://serde.rs/">a</a>
  28. procedural macro having to do with data structure serialization. The <code>#var</code>
  29. syntax performs interpolation of runtime variables into the quoted tokens.
  30. Check out the documentation of the <a href="macro.quote.html"><code>quote!</code></a> macro for more detail about
  31. the syntax. See also the <a href="macro.quote_spanned.html"><code>quote_spanned!</code></a> macro which is important for
  32. implementing hygienic procedural macros.</p>
  33. <pre class="rust rust-example-rendered">
  34. <span class="kw">let</span> <span class="ident">tokens</span> <span class="op">=</span> <span class="macro">quote</span><span class="macro">!</span> {
  35. <span class="kw">struct</span> <span class="ident">SerializeWith</span> #<span class="ident">generics</span> #<span class="ident">where_clause</span> {
  36. <span class="ident">value</span>: <span class="kw-2">&amp;</span><span class="lifetime">&#39;a</span> #<span class="ident">field_ty</span>,
  37. <span class="ident">phantom</span>: ::<span class="ident">std</span>::<span class="ident">marker</span>::<span class="ident">PhantomData</span><span class="op">&lt;</span>#<span class="ident">item_ty</span><span class="op">&gt;</span>,
  38. }
  39. <span class="kw">impl</span> #<span class="ident">generics</span> <span class="ident">serde</span>::<span class="ident">Serialize</span> <span class="kw">for</span> <span class="ident">SerializeWith</span> #<span class="ident">generics</span> #<span class="ident">where_clause</span> {
  40. <span class="kw">fn</span> <span class="ident">serialize</span><span class="op">&lt;</span><span class="ident">S</span><span class="op">&gt;</span>(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="ident">serializer</span>: <span class="ident">S</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">S</span>::<span class="prelude-val">Ok</span>, <span class="ident">S</span>::<span class="ident">Error</span><span class="op">&gt;</span>
  41. <span class="kw">where</span>
  42. <span class="ident">S</span>: <span class="ident">serde</span>::<span class="ident">Serializer</span>,
  43. {
  44. #<span class="ident">path</span>(<span class="self">self</span>.<span class="ident">value</span>, <span class="ident">serializer</span>)
  45. }
  46. }
  47. <span class="ident">SerializeWith</span> {
  48. <span class="ident">value</span>: #<span class="ident">value</span>,
  49. <span class="ident">phantom</span>: ::<span class="ident">std</span>::<span class="ident">marker</span>::<span class="ident">PhantomData</span>::<span class="op">&lt;</span>#<span class="ident">item_ty</span><span class="op">&gt;</span>,
  50. }
  51. };</pre>
  52. <h2 id="recursion-limit" class="section-header"><a href="#recursion-limit">Recursion limit</a></h2>
  53. <p>The <code>quote!</code> macro relies on deep recursion so some large invocations may
  54. fail with &quot;recursion limit reached&quot; when you compile. If it fails, bump up
  55. the recursion limit by adding <code>#![recursion_limit = &quot;128&quot;]</code> to your crate.
  56. An even higher limit may be necessary for especially large invocations.</p>
  57. </div><h2 id='macros' class='section-header'><a href="#macros">Macros</a></h2>
  58. <table>
  59. <tr class=' module-item'>
  60. <td><a class="macro" href="macro.quote.html"
  61. title='macro quote::quote'>quote</a></td>
  62. <td class='docblock-short'>
  63. <p>The whole point.</p>
  64. </td>
  65. </tr>
  66. <tr class=' module-item'>
  67. <td><a class="macro" href="macro.quote_spanned.html"
  68. title='macro quote::quote_spanned'>quote_spanned</a></td>
  69. <td class='docblock-short'>
  70. <p>Same as <code>quote!</code>, but applies a given span to all tokens originating within
  71. the macro invocation.</p>
  72. </td>
  73. </tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
  74. <table>
  75. <tr class=' module-item'>
  76. <td><a class="trait" href="trait.ToTokens.html"
  77. title='trait quote::ToTokens'>ToTokens</a></td>
  78. <td class='docblock-short'>
  79. <p>Types that can be interpolated inside a <a href="macro.quote.html"><code>quote!</code></a> invocation.</p>
  80. </td>
  81. </tr>
  82. <tr class=' module-item'>
  83. <td><a class="trait" href="trait.TokenStreamExt.html"
  84. title='trait quote::TokenStreamExt'>TokenStreamExt</a></td>
  85. <td class='docblock-short'>
  86. <p>TokenStream extension trait with methods for appending tokens.</p>
  87. </td>
  88. </tr></table></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 = "quote";</script><script src="../aliases.js"></script><script src="../main.js"></script><script defer src="../search-index.js"></script></body></html>