| <!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="Source of the Rust file `crates/parser/src/lib.rs`."><title>lib.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.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-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-84e720fa.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="parser" data-themes="" data-resource-suffix="" data-rustdoc-version="1.89.0 (29483883e 2025-08-04)" data-channel="1.89.0" data-search-js="search-92309212.js" data-settings-js="settings-5514c975.js" ><script src="../../static.files/storage-4e99c027.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-fd3af306.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-32bb7600.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">parser/</div>lib.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="doccomment">//! The Rust parser. |
| <a href=#2 id=2 data-nosnippet>2</a>//! |
| <a href=#3 id=3 data-nosnippet>3</a>//! NOTE: The crate is undergoing refactors, don't believe everything the docs |
| <a href=#4 id=4 data-nosnippet>4</a>//! say :-) |
| <a href=#5 id=5 data-nosnippet>5</a>//! |
| <a href=#6 id=6 data-nosnippet>6</a>//! The parser doesn't know about concrete representation of tokens and syntax |
| <a href=#7 id=7 data-nosnippet>7</a>//! trees. Abstract [`TokenSource`] and [`TreeSink`] traits are used instead. As |
| <a href=#8 id=8 data-nosnippet>8</a>//! a consequence, this crate does not contain a lexer. |
| <a href=#9 id=9 data-nosnippet>9</a>//! |
| <a href=#10 id=10 data-nosnippet>10</a>//! The [`Parser`] struct from the [`parser`] module is a cursor into the |
| <a href=#11 id=11 data-nosnippet>11</a>//! sequence of tokens. Parsing routines use [`Parser`] to inspect current |
| <a href=#12 id=12 data-nosnippet>12</a>//! state and advance the parsing. |
| <a href=#13 id=13 data-nosnippet>13</a>//! |
| <a href=#14 id=14 data-nosnippet>14</a>//! The actual parsing happens in the [`grammar`] module. |
| <a href=#15 id=15 data-nosnippet>15</a>//! |
| <a href=#16 id=16 data-nosnippet>16</a>//! Tests for this crate live in the `syntax` crate. |
| <a href=#17 id=17 data-nosnippet>17</a>//! |
| <a href=#18 id=18 data-nosnippet>18</a>//! [`Parser`]: crate::parser::Parser |
| <a href=#19 id=19 data-nosnippet>19</a> |
| <a href=#20 id=20 data-nosnippet>20</a></span><span class="attr">#![allow(rustdoc::private_intra_doc_links)] |
| <a href=#21 id=21 data-nosnippet>21</a>#![cfg_attr(feature = <span class="string">"in-rust-tree"</span>, feature(rustc_private))] |
| <a href=#22 id=22 data-nosnippet>22</a> |
| <a href=#23 id=23 data-nosnippet>23</a>#[cfg(not(feature = <span class="string">"in-rust-tree"</span>))] |
| <a href=#24 id=24 data-nosnippet>24</a></span><span class="kw">extern crate </span>ra_ap_rustc_lexer <span class="kw">as </span>rustc_lexer; |
| <a href=#25 id=25 data-nosnippet>25</a><span class="attr">#[cfg(feature = <span class="string">"in-rust-tree"</span>)] |
| <a href=#26 id=26 data-nosnippet>26</a></span><span class="kw">extern crate </span>rustc_lexer; |
| <a href=#27 id=27 data-nosnippet>27</a> |
| <a href=#28 id=28 data-nosnippet>28</a><span class="kw">mod </span>event; |
| <a href=#29 id=29 data-nosnippet>29</a><span class="kw">mod </span>grammar; |
| <a href=#30 id=30 data-nosnippet>30</a><span class="kw">mod </span>input; |
| <a href=#31 id=31 data-nosnippet>31</a><span class="kw">mod </span>lexed_str; |
| <a href=#32 id=32 data-nosnippet>32</a><span class="kw">mod </span>output; |
| <a href=#33 id=33 data-nosnippet>33</a><span class="kw">mod </span>parser; |
| <a href=#34 id=34 data-nosnippet>34</a><span class="kw">mod </span>shortcuts; |
| <a href=#35 id=35 data-nosnippet>35</a><span class="kw">mod </span>syntax_kind; |
| <a href=#36 id=36 data-nosnippet>36</a><span class="kw">mod </span>token_set; |
| <a href=#37 id=37 data-nosnippet>37</a> |
| <a href=#38 id=38 data-nosnippet>38</a><span class="kw">pub use </span>T_ <span class="kw">as </span>T; |
| <a href=#39 id=39 data-nosnippet>39</a> |
| <a href=#40 id=40 data-nosnippet>40</a><span class="attr">#[cfg(test)] |
| <a href=#41 id=41 data-nosnippet>41</a></span><span class="kw">mod </span>tests; |
| <a href=#42 id=42 data-nosnippet>42</a> |
| <a href=#43 id=43 data-nosnippet>43</a><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">use </span>token_set::TokenSet; |
| <a href=#44 id=44 data-nosnippet>44</a> |
| <a href=#45 id=45 data-nosnippet>45</a><span class="kw">pub use </span>edition::Edition; |
| <a href=#46 id=46 data-nosnippet>46</a> |
| <a href=#47 id=47 data-nosnippet>47</a><span class="kw">pub use crate</span>::{ |
| <a href=#48 id=48 data-nosnippet>48</a> input::Input, |
| <a href=#49 id=49 data-nosnippet>49</a> lexed_str::LexedStr, |
| <a href=#50 id=50 data-nosnippet>50</a> output::{Output, Step}, |
| <a href=#51 id=51 data-nosnippet>51</a> shortcuts::StrStep, |
| <a href=#52 id=52 data-nosnippet>52</a> syntax_kind::SyntaxKind, |
| <a href=#53 id=53 data-nosnippet>53</a>}; |
| <a href=#54 id=54 data-nosnippet>54</a> |
| <a href=#55 id=55 data-nosnippet>55</a><span class="doccomment">/// Parse the whole of the input as a given syntactic construct. |
| <a href=#56 id=56 data-nosnippet>56</a>/// |
| <a href=#57 id=57 data-nosnippet>57</a>/// This covers two main use-cases: |
| <a href=#58 id=58 data-nosnippet>58</a>/// |
| <a href=#59 id=59 data-nosnippet>59</a>/// * Parsing a Rust file. |
| <a href=#60 id=60 data-nosnippet>60</a>/// * Parsing a result of macro expansion. |
| <a href=#61 id=61 data-nosnippet>61</a>/// |
| <a href=#62 id=62 data-nosnippet>62</a>/// That is, for something like |
| <a href=#63 id=63 data-nosnippet>63</a>/// |
| <a href=#64 id=64 data-nosnippet>64</a>/// ```ignore |
| <a href=#65 id=65 data-nosnippet>65</a>/// quick_check! { |
| <a href=#66 id=66 data-nosnippet>66</a>/// fn prop() {} |
| <a href=#67 id=67 data-nosnippet>67</a>/// } |
| <a href=#68 id=68 data-nosnippet>68</a>/// ``` |
| <a href=#69 id=69 data-nosnippet>69</a>/// |
| <a href=#70 id=70 data-nosnippet>70</a>/// the input to the macro will be parsed with [`PrefixEntryPoint::Item`], and |
| <a href=#71 id=71 data-nosnippet>71</a>/// the result will be [`TopEntryPoint::MacroItems`]. |
| <a href=#72 id=72 data-nosnippet>72</a>/// |
| <a href=#73 id=73 data-nosnippet>73</a>/// [`TopEntryPoint::parse`] makes a guarantee that |
| <a href=#74 id=74 data-nosnippet>74</a>/// * all input is consumed |
| <a href=#75 id=75 data-nosnippet>75</a>/// * the result is a valid tree (there's one root node) |
| <a href=#76 id=76 data-nosnippet>76</a></span><span class="attr">#[derive(Debug)] |
| <a href=#77 id=77 data-nosnippet>77</a></span><span class="kw">pub enum </span>TopEntryPoint { |
| <a href=#78 id=78 data-nosnippet>78</a> SourceFile, |
| <a href=#79 id=79 data-nosnippet>79</a> MacroStmts, |
| <a href=#80 id=80 data-nosnippet>80</a> MacroItems, |
| <a href=#81 id=81 data-nosnippet>81</a> Pattern, |
| <a href=#82 id=82 data-nosnippet>82</a> Type, |
| <a href=#83 id=83 data-nosnippet>83</a> Expr, |
| <a href=#84 id=84 data-nosnippet>84</a> <span class="doccomment">/// Edge case -- macros generally don't expand to attributes, with the |
| <a href=#85 id=85 data-nosnippet>85</a> /// exception of `cfg_attr` which does! |
| <a href=#86 id=86 data-nosnippet>86</a> </span>MetaItem, |
| <a href=#87 id=87 data-nosnippet>87</a>} |
| <a href=#88 id=88 data-nosnippet>88</a> |
| <a href=#89 id=89 data-nosnippet>89</a><span class="kw">impl </span>TopEntryPoint { |
| <a href=#90 id=90 data-nosnippet>90</a> <span class="kw">pub fn </span>parse(<span class="kw-2">&</span><span class="self">self</span>, input: <span class="kw-2">&</span>Input, edition: Edition) -> Output { |
| <a href=#91 id=91 data-nosnippet>91</a> <span class="kw">let </span>_p = <span class="macro">tracing::info_span!</span>(<span class="string">"TopEntryPoint::parse"</span>, <span class="question-mark">?</span><span class="self">self</span>).entered(); |
| <a href=#92 id=92 data-nosnippet>92</a> <span class="kw">let </span>entry_point: <span class="kw">fn</span>(<span class="kw-2">&</span><span class="lifetime">'_ </span><span class="kw-2">mut </span>parser::Parser<<span class="lifetime">'_</span>>) = <span class="kw">match </span><span class="self">self </span>{ |
| <a href=#93 id=93 data-nosnippet>93</a> TopEntryPoint::SourceFile => grammar::entry::top::source_file, |
| <a href=#94 id=94 data-nosnippet>94</a> TopEntryPoint::MacroStmts => grammar::entry::top::macro_stmts, |
| <a href=#95 id=95 data-nosnippet>95</a> TopEntryPoint::MacroItems => grammar::entry::top::macro_items, |
| <a href=#96 id=96 data-nosnippet>96</a> TopEntryPoint::Pattern => grammar::entry::top::pattern, |
| <a href=#97 id=97 data-nosnippet>97</a> TopEntryPoint::Type => grammar::entry::top::type_, |
| <a href=#98 id=98 data-nosnippet>98</a> TopEntryPoint::Expr => grammar::entry::top::expr, |
| <a href=#99 id=99 data-nosnippet>99</a> TopEntryPoint::MetaItem => grammar::entry::top::meta_item, |
| <a href=#100 id=100 data-nosnippet>100</a> }; |
| <a href=#101 id=101 data-nosnippet>101</a> <span class="kw">let </span><span class="kw-2">mut </span>p = parser::Parser::new(input, edition); |
| <a href=#102 id=102 data-nosnippet>102</a> entry_point(<span class="kw-2">&mut </span>p); |
| <a href=#103 id=103 data-nosnippet>103</a> <span class="kw">let </span>events = p.finish(); |
| <a href=#104 id=104 data-nosnippet>104</a> <span class="kw">let </span>res = event::process(events); |
| <a href=#105 id=105 data-nosnippet>105</a> |
| <a href=#106 id=106 data-nosnippet>106</a> <span class="kw">if </span><span class="macro">cfg!</span>(debug_assertions) { |
| <a href=#107 id=107 data-nosnippet>107</a> <span class="kw">let </span><span class="kw-2">mut </span>depth = <span class="number">0</span>; |
| <a href=#108 id=108 data-nosnippet>108</a> <span class="kw">let </span><span class="kw-2">mut </span>first = <span class="bool-val">true</span>; |
| <a href=#109 id=109 data-nosnippet>109</a> <span class="kw">for </span>step <span class="kw">in </span>res.iter() { |
| <a href=#110 id=110 data-nosnippet>110</a> <span class="macro">assert!</span>(depth > <span class="number">0 </span>|| first); |
| <a href=#111 id=111 data-nosnippet>111</a> first = <span class="bool-val">false</span>; |
| <a href=#112 id=112 data-nosnippet>112</a> <span class="kw">match </span>step { |
| <a href=#113 id=113 data-nosnippet>113</a> Step::Enter { .. } => depth += <span class="number">1</span>, |
| <a href=#114 id=114 data-nosnippet>114</a> Step::Exit => depth -= <span class="number">1</span>, |
| <a href=#115 id=115 data-nosnippet>115</a> Step::FloatSplit { ends_in_dot: has_pseudo_dot } => { |
| <a href=#116 id=116 data-nosnippet>116</a> depth -= <span class="number">1 </span>+ !has_pseudo_dot <span class="kw">as </span>usize |
| <a href=#117 id=117 data-nosnippet>117</a> } |
| <a href=#118 id=118 data-nosnippet>118</a> Step::Token { .. } | Step::Error { .. } => (), |
| <a href=#119 id=119 data-nosnippet>119</a> } |
| <a href=#120 id=120 data-nosnippet>120</a> } |
| <a href=#121 id=121 data-nosnippet>121</a> <span class="macro">assert!</span>(!first, <span class="string">"no tree at all"</span>); |
| <a href=#122 id=122 data-nosnippet>122</a> <span class="macro">assert_eq!</span>(depth, <span class="number">0</span>, <span class="string">"unbalanced tree"</span>); |
| <a href=#123 id=123 data-nosnippet>123</a> } |
| <a href=#124 id=124 data-nosnippet>124</a> |
| <a href=#125 id=125 data-nosnippet>125</a> res |
| <a href=#126 id=126 data-nosnippet>126</a> } |
| <a href=#127 id=127 data-nosnippet>127</a>} |
| <a href=#128 id=128 data-nosnippet>128</a> |
| <a href=#129 id=129 data-nosnippet>129</a><span class="doccomment">/// Parse a prefix of the input as a given syntactic construct. |
| <a href=#130 id=130 data-nosnippet>130</a>/// |
| <a href=#131 id=131 data-nosnippet>131</a>/// This is used by macro-by-example parser to implement things like `$i:item` |
| <a href=#132 id=132 data-nosnippet>132</a>/// and the naming of variants follows the naming of macro fragments. |
| <a href=#133 id=133 data-nosnippet>133</a>/// |
| <a href=#134 id=134 data-nosnippet>134</a>/// Note that this is generally non-optional -- the result is intentionally not |
| <a href=#135 id=135 data-nosnippet>135</a>/// `Option<Output>`. The way MBE work, by the time we *try* to parse `$e:expr` |
| <a href=#136 id=136 data-nosnippet>136</a>/// we already commit to expression. In other words, this API by design can't be |
| <a href=#137 id=137 data-nosnippet>137</a>/// used to implement "rollback and try another alternative" logic. |
| <a href=#138 id=138 data-nosnippet>138</a></span><span class="attr">#[derive(Debug)] |
| <a href=#139 id=139 data-nosnippet>139</a></span><span class="kw">pub enum </span>PrefixEntryPoint { |
| <a href=#140 id=140 data-nosnippet>140</a> Vis, |
| <a href=#141 id=141 data-nosnippet>141</a> Block, |
| <a href=#142 id=142 data-nosnippet>142</a> Stmt, |
| <a href=#143 id=143 data-nosnippet>143</a> Pat, |
| <a href=#144 id=144 data-nosnippet>144</a> PatTop, |
| <a href=#145 id=145 data-nosnippet>145</a> Ty, |
| <a href=#146 id=146 data-nosnippet>146</a> Expr, |
| <a href=#147 id=147 data-nosnippet>147</a> Path, |
| <a href=#148 id=148 data-nosnippet>148</a> Item, |
| <a href=#149 id=149 data-nosnippet>149</a> MetaItem, |
| <a href=#150 id=150 data-nosnippet>150</a>} |
| <a href=#151 id=151 data-nosnippet>151</a> |
| <a href=#152 id=152 data-nosnippet>152</a><span class="kw">impl </span>PrefixEntryPoint { |
| <a href=#153 id=153 data-nosnippet>153</a> <span class="kw">pub fn </span>parse(<span class="kw-2">&</span><span class="self">self</span>, input: <span class="kw-2">&</span>Input, edition: Edition) -> Output { |
| <a href=#154 id=154 data-nosnippet>154</a> <span class="kw">let </span>entry_point: <span class="kw">fn</span>(<span class="kw-2">&</span><span class="lifetime">'_ </span><span class="kw-2">mut </span>parser::Parser<<span class="lifetime">'_</span>>) = <span class="kw">match </span><span class="self">self </span>{ |
| <a href=#155 id=155 data-nosnippet>155</a> PrefixEntryPoint::Vis => grammar::entry::prefix::vis, |
| <a href=#156 id=156 data-nosnippet>156</a> PrefixEntryPoint::Block => grammar::entry::prefix::block, |
| <a href=#157 id=157 data-nosnippet>157</a> PrefixEntryPoint::Stmt => grammar::entry::prefix::stmt, |
| <a href=#158 id=158 data-nosnippet>158</a> PrefixEntryPoint::Pat => grammar::entry::prefix::pat, |
| <a href=#159 id=159 data-nosnippet>159</a> PrefixEntryPoint::PatTop => grammar::entry::prefix::pat_top, |
| <a href=#160 id=160 data-nosnippet>160</a> PrefixEntryPoint::Ty => grammar::entry::prefix::ty, |
| <a href=#161 id=161 data-nosnippet>161</a> PrefixEntryPoint::Expr => grammar::entry::prefix::expr, |
| <a href=#162 id=162 data-nosnippet>162</a> PrefixEntryPoint::Path => grammar::entry::prefix::path, |
| <a href=#163 id=163 data-nosnippet>163</a> PrefixEntryPoint::Item => grammar::entry::prefix::item, |
| <a href=#164 id=164 data-nosnippet>164</a> PrefixEntryPoint::MetaItem => grammar::entry::prefix::meta_item, |
| <a href=#165 id=165 data-nosnippet>165</a> }; |
| <a href=#166 id=166 data-nosnippet>166</a> <span class="kw">let </span><span class="kw-2">mut </span>p = parser::Parser::new(input, edition); |
| <a href=#167 id=167 data-nosnippet>167</a> entry_point(<span class="kw-2">&mut </span>p); |
| <a href=#168 id=168 data-nosnippet>168</a> <span class="kw">let </span>events = p.finish(); |
| <a href=#169 id=169 data-nosnippet>169</a> event::process(events) |
| <a href=#170 id=170 data-nosnippet>170</a> } |
| <a href=#171 id=171 data-nosnippet>171</a>} |
| <a href=#172 id=172 data-nosnippet>172</a> |
| <a href=#173 id=173 data-nosnippet>173</a><span class="doccomment">/// A parsing function for a specific braced-block. |
| <a href=#174 id=174 data-nosnippet>174</a></span><span class="kw">pub struct </span>Reparser(<span class="kw">fn</span>(<span class="kw-2">&mut </span>parser::Parser<<span class="lifetime">'_</span>>)); |
| <a href=#175 id=175 data-nosnippet>175</a> |
| <a href=#176 id=176 data-nosnippet>176</a><span class="kw">impl </span>Reparser { |
| <a href=#177 id=177 data-nosnippet>177</a> <span class="doccomment">/// If the node is a braced block, return the corresponding `Reparser`. |
| <a href=#178 id=178 data-nosnippet>178</a> </span><span class="kw">pub fn </span>for_node( |
| <a href=#179 id=179 data-nosnippet>179</a> node: SyntaxKind, |
| <a href=#180 id=180 data-nosnippet>180</a> first_child: <span class="prelude-ty">Option</span><SyntaxKind>, |
| <a href=#181 id=181 data-nosnippet>181</a> parent: <span class="prelude-ty">Option</span><SyntaxKind>, |
| <a href=#182 id=182 data-nosnippet>182</a> ) -> <span class="prelude-ty">Option</span><Reparser> { |
| <a href=#183 id=183 data-nosnippet>183</a> grammar::reparser(node, first_child, parent).map(Reparser) |
| <a href=#184 id=184 data-nosnippet>184</a> } |
| <a href=#185 id=185 data-nosnippet>185</a> |
| <a href=#186 id=186 data-nosnippet>186</a> <span class="doccomment">/// Re-parse given tokens using this `Reparser`. |
| <a href=#187 id=187 data-nosnippet>187</a> /// |
| <a href=#188 id=188 data-nosnippet>188</a> /// Tokens must start with `{`, end with `}` and form a valid brace |
| <a href=#189 id=189 data-nosnippet>189</a> /// sequence. |
| <a href=#190 id=190 data-nosnippet>190</a> </span><span class="kw">pub fn </span>parse(<span class="self">self</span>, tokens: <span class="kw-2">&</span>Input, edition: Edition) -> Output { |
| <a href=#191 id=191 data-nosnippet>191</a> <span class="kw">let </span>Reparser(r) = <span class="self">self</span>; |
| <a href=#192 id=192 data-nosnippet>192</a> <span class="kw">let </span><span class="kw-2">mut </span>p = parser::Parser::new(tokens, edition); |
| <a href=#193 id=193 data-nosnippet>193</a> r(<span class="kw-2">&mut </span>p); |
| <a href=#194 id=194 data-nosnippet>194</a> <span class="kw">let </span>events = p.finish(); |
| <a href=#195 id=195 data-nosnippet>195</a> event::process(events) |
| <a href=#196 id=196 data-nosnippet>196</a> } |
| <a href=#197 id=197 data-nosnippet>197</a>}</code></pre></div></section></main></body></html> |
