1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Parser Grammar</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Spirit 2.5.8"> 8<link rel="up" href="../nonterminal.html" title="Nonterminal Parsers"> 9<link rel="prev" href="rule.html" title="Parser Rule"> 10<link rel="next" href="../numeric.html" title="Numeric Parsers"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a 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name="spirit.qi.reference.nonterminal.grammar.h0"></a> 31 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.description"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.description">Description</a> 32 </h6> 33<p> 34 The grammar encapsulates a set of <a class="link" href="rule.html" title="Parser Rule">rules</a> 35 (as well as primitive parsers (<a class="link" href="../parser_concepts/primitiveparser.html" title="PrimitiveParser"><code class="computeroutput"><span class="identifier">PrimitiveParser</span></code></a>) and sub-grammars). 36 The grammar is the main mechanism for modularization and composition. 37 Grammars can be composed to form more complex grammars. 38 </p> 39<h6> 40<a name="spirit.qi.reference.nonterminal.grammar.h1"></a> 41 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.header"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.header">Header</a> 42 </h6> 43<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/qi/nonterminal/grammar.hpp></span> 44<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">qi_grammar</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 45</pre> 46<p> 47 Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. 48 </p> 49<h6> 50<a name="spirit.qi.reference.nonterminal.grammar.h2"></a> 51 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.namespace"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.namespace">Namespace</a> 52 </h6> 53<div class="informaltable"><table class="table"> 54<colgroup><col></colgroup> 55<thead><tr><th> 56 <p> 57 Name 58 </p> 59 </th></tr></thead> 60<tbody><tr><td> 61 <p> 62 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">grammar</span></code> 63 </p> 64 </td></tr></tbody> 65</table></div> 66<h6> 67<a name="spirit.qi.reference.nonterminal.grammar.h3"></a> 68 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.synopsis"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.synopsis">Synopsis</a> 69 </h6> 70<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">A1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">A2</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">A3</span><span class="special">></span> 71<span class="keyword">struct</span> <span class="identifier">grammar</span><span class="special">;</span> 72</pre> 73<h6> 74<a name="spirit.qi.reference.nonterminal.grammar.h4"></a> 75 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.template_parameters"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.template_parameters">Template 76 parameters</a> 77 </h6> 78<div class="informaltable"><table class="table"> 79<colgroup> 80<col> 81<col> 82<col> 83</colgroup> 84<thead><tr> 85<th> 86 <p> 87 Parameter 88 </p> 89 </th> 90<th> 91 <p> 92 Description 93 </p> 94 </th> 95<th> 96 <p> 97 Default 98 </p> 99 </th> 100</tr></thead> 101<tbody> 102<tr> 103<td> 104 <p> 105 <code class="computeroutput"><span class="identifier">Iterator</span></code> 106 </p> 107 </td> 108<td> 109 <p> 110 The underlying iterator type that the rule is expected to work 111 on. 112 </p> 113 </td> 114<td> 115 <p> 116 none 117 </p> 118 </td> 119</tr> 120<tr> 121<td> 122 <p> 123 <code class="computeroutput"><span class="identifier">A1</span></code>, <code class="computeroutput"><span class="identifier">A2</span></code>, <code class="computeroutput"><span class="identifier">A3</span></code> 124 </p> 125 </td> 126<td> 127 <p> 128 Either <code class="computeroutput"><span class="identifier">Signature</span></code>, 129 <code class="computeroutput"><span class="identifier">Skipper</span></code> or 130 <code class="computeroutput"><span class="identifier">Locals</span></code> in any 131 order. See table below. 132 </p> 133 </td> 134<td> 135 <p> 136 See table below. 137 </p> 138 </td> 139</tr> 140</tbody> 141</table></div> 142<p> 143 Here is more information about the template parameters: 144 </p> 145<div class="informaltable"><table class="table"> 146<colgroup> 147<col> 148<col> 149<col> 150</colgroup> 151<thead><tr> 152<th> 153 <p> 154 Parameter 155 </p> 156 </th> 157<th> 158 <p> 159 Description 160 </p> 161 </th> 162<th> 163 <p> 164 Default 165 </p> 166 </th> 167</tr></thead> 168<tbody> 169<tr> 170<td> 171 <p> 172 <code class="computeroutput"><span class="identifier">Signature</span></code> 173 </p> 174 </td> 175<td> 176 <p> 177 Specifies the grammar's synthesized (return value) and inherited 178 attributes (arguments). More on this here: <a class="link" href="../parser_concepts/nonterminal.html" title="Nonterminal"><code class="computeroutput"><span class="identifier">Nonterminal</span></code></a>. 179 </p> 180 </td> 181<td> 182 <p> 183 <code class="computeroutput"><span class="identifier">unused_type</span></code>. 184 When <code class="computeroutput"><span class="identifier">Signature</span></code> 185 defaults to <code class="computeroutput"><span class="identifier">unused_type</span></code>, 186 the effect is the same as specifying a signature of <code class="computeroutput"><span class="keyword">void</span><span class="special">()</span></code> 187 which is also equivalent to <code class="computeroutput"><span class="identifier">unused_type</span><span class="special">()</span></code> 188 </p> 189 </td> 190</tr> 191<tr> 192<td> 193 <p> 194 <code class="computeroutput"><span class="identifier">Skipper</span></code> 195 </p> 196 </td> 197<td> 198 <p> 199 Specifies the grammar's skipper parser. Specify this if you 200 want the grammar to skip white spaces. 201 </p> 202 </td> 203<td> 204 <p> 205 <code class="computeroutput"><span class="identifier">unused_type</span></code> 206 </p> 207 </td> 208</tr> 209<tr> 210<td> 211 <p> 212 <code class="computeroutput"><span class="identifier">Locals</span></code> 213 </p> 214 </td> 215<td> 216 <p> 217 Specifies the grammar's local variables. See <a class="link" href="../parser_concepts/nonterminal.html" title="Nonterminal"><code class="computeroutput"><span class="identifier">Nonterminal</span></code></a>. 218 </p> 219 </td> 220<td> 221 <p> 222 <code class="computeroutput"><span class="identifier">unused_type</span></code> 223 </p> 224 </td> 225</tr> 226</tbody> 227</table></div> 228<h6> 229<a name="spirit.qi.reference.nonterminal.grammar.h5"></a> 230 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.model_of"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.model_of">Model of</a> 231 </h6> 232<div class="blockquote"><blockquote class="blockquote"><p> 233 <a class="link" href="../parser_concepts/nonterminal.html" title="Nonterminal"><code class="computeroutput"><span class="identifier">Nonterminal</span></code></a> 234 </p></blockquote></div> 235<div class="variablelist"> 236<p class="title"><b>Notation</b></p> 237<dl class="variablelist"> 238<dt><span class="term"><code class="computeroutput"><span class="identifier">g</span></code></span></dt> 239<dd><p> 240 A grammar 241 </p></dd> 242</dl> 243</div> 244<h6> 245<a name="spirit.qi.reference.nonterminal.grammar.h6"></a> 246 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.expression_semantics"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.expression_semantics">Expression 247 Semantics</a> 248 </h6> 249<p> 250 Semantics of an expression is defined only where it differs from, or 251 is not defined in <a class="link" href="../parser_concepts/nonterminal.html" title="Nonterminal"><code class="computeroutput"><span class="identifier">Nonterminal</span></code></a>. 252 </p> 253<div class="informaltable"><table class="table"> 254<colgroup> 255<col> 256<col> 257</colgroup> 258<thead><tr> 259<th> 260 <p> 261 Expression 262 </p> 263 </th> 264<th> 265 <p> 266 Semantics 267 </p> 268 </th> 269</tr></thead> 270<tbody><tr> 271<td> 272 <p> 273</p> 274<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span> 275<span class="keyword">struct</span> <span class="identifier">my_grammar</span> <span class="special">:</span> <span class="identifier">grammar</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">,</span> <span class="identifier">A2</span><span class="special">,</span> <span class="identifier">A3</span><span class="special">></span> 276<span class="special">{</span> 277 <span class="identifier">my_grammar</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">my_grammar</span><span class="special">::</span><span class="identifier">base_type</span><span class="special">(</span><span class="identifier">start</span><span class="special">,</span> <span class="identifier">name</span><span class="special">)</span> 278 <span class="special">{</span> 279 <span class="comment">// Rule definitions</span> 280 <span class="identifier">start</span> <span class="special">=</span> <span class="comment">/* ... */</span><span class="special">;</span> 281 <span class="special">}</span> 282 283 <span class="identifier">rule</span><span class="special"><</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">,</span> <span class="identifier">A2</span><span class="special">,</span> <span class="identifier">A3</span><span class="special">></span> <span class="identifier">start</span><span class="special">;</span> 284 <span class="comment">// more rule declarations...</span> 285<span class="special">};</span> 286</pre> 287<p> 288 </p> 289 </td> 290<td> 291 <p> 292 Grammar definition. <code class="computeroutput"><span class="identifier">name</span></code> 293 is an optional string that gives the grammar its name, useful 294 for debugging and error handling. 295 </p> 296 </td> 297</tr></tbody> 298</table></div> 299<div class="note"><table border="0" summary="Note"> 300<tr> 301<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 302<th align="left">Note</th> 303</tr> 304<tr><td align="left" valign="top"><p> 305 The template parameters of a grammar and its start rule (the rule passed 306 to the grammar's base class constructor) must match, otherwise you 307 will see compilation errors. 308 </p></td></tr> 309</table></div> 310<h6> 311<a name="spirit.qi.reference.nonterminal.grammar.h7"></a> 312 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.attributes"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.attributes">Attributes</a> 313 </h6> 314<div class="blockquote"><blockquote class="blockquote"><p> 315 The parser attribute of the grammar is <code class="computeroutput"><span class="identifier">T</span></code>, 316 its synthesized attribute. See <a class="link" href="../parser_concepts/nonterminal.html#spirit.qi.reference.parser_concepts.nonterminal.attributes"><code class="computeroutput"><span class="identifier">Attribute</span></code></a> 317 </p></blockquote></div> 318<h6> 319<a name="spirit.qi.reference.nonterminal.grammar.h8"></a> 320 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.complexity"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.complexity">Complexity</a> 321 </h6> 322<div class="blockquote"><blockquote class="blockquote"><p> 323 The complexity is defined by the complexity of the its definition. 324 </p></blockquote></div> 325<h6> 326<a name="spirit.qi.reference.nonterminal.grammar.h9"></a> 327 <span class="phrase"><a name="spirit.qi.reference.nonterminal.grammar.example"></a></span><a class="link" href="grammar.html#spirit.qi.reference.nonterminal.grammar.example">Example</a> 328 </h6> 329<div class="note"><table border="0" summary="Note"> 330<tr> 331<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 332<th align="left">Note</th> 333</tr> 334<tr><td align="left" valign="top"><p> 335 The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.qi.reference.basics.examples">Basics Examples</a> 336 section. 337 </p></td></tr> 338</table></div> 339<p> 340 Some using declarations: 341 </p> 342<p> 343</p> 344<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">ascii</span><span class="special">::</span><span class="identifier">space_type</span><span class="special">;</span> 345<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">int_</span><span class="special">;</span> 346<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">grammar</span><span class="special">;</span> 347<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">::</span><span class="identifier">rule</span><span class="special">;</span> 348</pre> 349<p> 350 </p> 351<p> 352 Basic grammar usage: 353 </p> 354<p> 355</p> 356<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">num_list</span> <span class="special">:</span> <span class="identifier">grammar</span><span class="special"><</span><span class="keyword">char</span> <span class="keyword">const</span><span class="special">*,</span> <span class="identifier">space_type</span><span class="special">></span> 357<span class="special">{</span> 358 <span class="identifier">num_list</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">start</span><span class="special">)</span> 359 <span class="special">{</span> 360 <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">int_</span><span class="special">;</span> 361 <span class="identifier">num</span> <span class="special">=</span> <span class="identifier">int_</span><span class="special">;</span> 362 <span class="identifier">start</span> <span class="special">=</span> <span class="identifier">num</span> <span class="special">>></span> <span class="special">*(</span><span class="char">','</span> <span class="special">>></span> <span class="identifier">num</span><span class="special">);</span> 363 <span class="special">}</span> 364 365 <span class="identifier">rule</span><span class="special"><</span><span class="keyword">char</span> <span class="keyword">const</span><span class="special">*,</span> <span class="identifier">space_type</span><span class="special">></span> <span class="identifier">start</span><span class="special">,</span> <span class="identifier">num</span><span class="special">;</span> 366<span class="special">};</span> 367</pre> 368<p> 369 </p> 370<p> 371 How to use the example grammar: 372 </p> 373<p> 374</p> 375<pre class="programlisting"><span class="identifier">num_list</span> <span class="identifier">nlist</span><span class="special">;</span> 376<span class="identifier">test_phrase_parser</span><span class="special">(</span><span class="string">"123, 456, 789"</span><span class="special">,</span> <span class="identifier">nlist</span><span class="special">);</span> 377</pre> 378<p> 379 </p> 380</div> 381<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 382<td align="left"></td> 383<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p> 384 Distributed under the Boost Software License, Version 1.0. (See accompanying 385 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 386 </p> 387</div></td> 388</tr></table> 389<hr> 390<div class="spirit-nav"> 391<a accesskey="p" href="rule.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../nonterminal.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../numeric.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 392</div> 393</body> 394</html> 395
