1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Repetition Generator Directive (repeat[])</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="../directive.html" title="Generator Directives"> 9<link rel="prev" href="alignment.html" title="Alignment Generator Directives (left_align[], center[], right_align[])"> 10<link rel="next" href="delimit.html" title="Generator Directives Controlling Automatic Delimiting (verbatim[], no_delimit[], delimit[])"> 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 href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="alignment.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.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="delimit.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="spirit.karma.reference.directive.repeat"></a><a class="link" href="repeat.html" title="Repetition Generator Directive (repeat[])">Repetition 28 Generator Directive (<code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code>)</a> 29</h5></div></div></div> 30<h6> 31<a name="spirit.karma.reference.directive.repeat.h0"></a> 32 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.description"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.description">Description</a> 33 </h6> 34<p> 35 The repetition directive allows to repeat an arbitrary generator expression 36 while optionally specifying the lower and upper repetition counts. It 37 provides a more powerful and flexible mechanism for repeating a generator. 38 There are grammars that are impractical and cumbersome, if not impossible, 39 for the basic EBNF iteration syntax ( <a class="link" href="../operator/kleene.html" title="Kleene Star Generator (*a)">unary 40 <code class="computeroutput"><span class="char">'*'</span></code></a> and the <a class="link" href="../operator/plus.html" title="Plus Generator (+a)">unary 41 <code class="computeroutput"><span class="char">'+'</span></code></a>) to specify. Examples: 42 </p> 43<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 44<li class="listitem"> 45 A file name may have a maximum of 255 characters only. 46 </li> 47<li class="listitem"> 48 A specific bitmap file format has exactly 4096 RGB color information. 49 </li> 50<li class="listitem"> 51 A 256 bit binary string (1..256 1s or 0s). 52 </li> 53</ul></div> 54<h6> 55<a name="spirit.karma.reference.directive.repeat.h1"></a> 56 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.header"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.header">Header</a> 57 </h6> 58<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/directive/repeat.hpp></span> 59<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">karma_repeat</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 60</pre> 61<p> 62 Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. 63 </p> 64<h6> 65<a name="spirit.karma.reference.directive.repeat.h2"></a> 66 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.namespace"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.namespace">Namespace</a> 67 </h6> 68<div class="informaltable"><table class="table"> 69<colgroup><col></colgroup> 70<thead><tr><th> 71 <p> 72 Name 73 </p> 74 </th></tr></thead> 75<tbody> 76<tr><td> 77 <p> 78 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">repeat</span> <span class="comment">// 79 alias: boost::spirit::karma::repeat</span></code> 80 </p> 81 </td></tr> 82<tr><td> 83 <p> 84 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">inf</span> <span class="comment">// alias: 85 boost::spirit::karma::inf</span></code> 86 </p> 87 </td></tr> 88</tbody> 89</table></div> 90<h6> 91<a name="spirit.karma.reference.directive.repeat.h3"></a> 92 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.model_of"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.model_of">Model of</a> 93 </h6> 94<div class="blockquote"><blockquote class="blockquote"><p> 95 <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a> 96 </p></blockquote></div> 97<div class="variablelist"> 98<p class="title"><b>Notation</b></p> 99<dl class="variablelist"> 100<dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt> 101<dd><p> 102 A generator object 103 </p></dd> 104<dt><span class="term"><code class="computeroutput"><span class="identifier">num</span><span class="special">,</span> 105 <span class="identifier">num1</span><span class="special">,</span> 106 <span class="identifier">num2</span></code></span></dt> 107<dd><p> 108 Numeric literals, any unsigned integer value, or a <a class="link" href="../basics.html#spirit.karma.reference.basics.lazy_argument">Lazy 109 Argument</a> that evaluates to an unsigned integer value 110 </p></dd> 111<dt><span class="term"><code class="computeroutput"><span class="identifier">inf</span></code></span></dt> 112<dd><p> 113 Placeholder expression standing for 'no upper repeat limit' 114 </p></dd> 115</dl> 116</div> 117<h6> 118<a name="spirit.karma.reference.directive.repeat.h4"></a> 119 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.expression_semantics"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.expression_semantics">Expression 120 Semantics</a> 121 </h6> 122<p> 123 Semantics of an expression is defined only where it differs from, or 124 is not defined in <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a>. 125 </p> 126<div class="informaltable"><table class="table"> 127<colgroup> 128<col> 129<col> 130</colgroup> 131<thead><tr> 132<th> 133 <p> 134 Expression 135 </p> 136 </th> 137<th> 138 <p> 139 Semantics 140 </p> 141 </th> 142</tr></thead> 143<tbody> 144<tr> 145<td> 146 <p> 147 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 148 </p> 149 </td> 150<td> 151 <p> 152 Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code> 153 zero or more times. This generator succeeds as long as its 154 embedded generator <code class="computeroutput"><span class="identifier">a</span></code> 155 does not fail (except if the underlying output stream reports 156 an error). This variant of <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> is semantically equivalent 157 to the <a class="link" href="../operator/kleene.html" title="Kleene Star Generator (*a)">Kleene 158 Star operator <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code></a> 159 </p> 160 </td> 161</tr> 162<tr> 163<td> 164 <p> 165 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 166 </p> 167 </td> 168<td> 169 <p> 170 Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code> 171 exactly <code class="computeroutput"><span class="identifier">num</span></code> 172 times. This generator succeeds as long as its embedded generator 173 <code class="computeroutput"><span class="identifier">a</span></code> does not 174 fail and as long as the associated attribute (container) contains 175 at least <code class="computeroutput"><span class="identifier">num</span></code> 176 elements (unless the underlying output stream reports an error). 177 </p> 178 </td> 179</tr> 180<tr> 181<td> 182 <p> 183 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> 184 <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 185 </p> 186 </td> 187<td> 188 <p> 189 Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code> 190 at least <code class="computeroutput"><span class="identifier">num1</span></code> 191 times but not more than <code class="computeroutput"><span class="identifier">num2</span></code> 192 times. This generator succeeds as long as its embedded generator 193 <code class="computeroutput"><span class="identifier">a</span></code> does not 194 fail and as long as the associated attribute (container) contains 195 at least <code class="computeroutput"><span class="identifier">num1</span></code> 196 elements (unless the underlying output stream reports an error). 197 If the associated attribute (container) does contain more than 198 <code class="computeroutput"><span class="identifier">num2</span></code> elements, 199 this directive limits the repeat count to <code class="computeroutput"><span class="identifier">num2</span></code>. 200 </p> 201 </td> 202</tr> 203<tr> 204<td> 205 <p> 206 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> 207 <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 208 </p> 209 </td> 210<td> 211 <p> 212 Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code> 213 at least <code class="computeroutput"><span class="identifier">num1</span></code> 214 times. No upper limit for the repeat count is set. This generator 215 succeeds as long as its embedded generator <code class="computeroutput"><span class="identifier">a</span></code> 216 does not fail and as long as the associated attribute (container) 217 contains at least <code class="computeroutput"><span class="identifier">num</span></code> 218 elements (unless the underlying output stream reports an error). 219 </p> 220 </td> 221</tr> 222</tbody> 223</table></div> 224<div class="note"><table border="0" summary="Note"> 225<tr> 226<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 227<th align="left">Note</th> 228</tr> 229<tr><td align="left" valign="top"><p> 230 All failing iterations of the embedded generator will consume one element 231 from the supplied attribute. The overall <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> will succeed as long as the iteration 232 criteria (number of successful invocations of the embedded generator) 233 is fulfilled (unless the underlying output stream reports an error). 234 </p></td></tr> 235</table></div> 236<h6> 237<a name="spirit.karma.reference.directive.repeat.h5"></a> 238 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.attributes"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.attributes">Attributes</a> 239 </h6> 240<p> 241 See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.karma.quick_reference.compound_attribute_rules.notation">Compound 242 Attribute Notation</a>. 243 </p> 244<div class="informaltable"><table class="table"> 245<colgroup> 246<col> 247<col> 248</colgroup> 249<thead><tr> 250<th> 251 <p> 252 Expression 253 </p> 254 </th> 255<th> 256 <p> 257 Attribute 258 </p> 259 </th> 260</tr></thead> 261<tbody> 262<tr> 263<td> 264 <p> 265 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> 266 </p> 267 </td> 268<td> 269 <p> 270</p> 271<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span> 272<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> 273<p> 274 </p> 275 </td> 276</tr> 277<tr> 278<td> 279 <p> 280 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 281 </p> 282 </td> 283<td> 284 <p> 285</p> 286<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span> 287<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> 288<p> 289 </p> 290 </td> 291</tr> 292<tr> 293<td> 294 <p> 295 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> 296 <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 297 </p> 298 </td> 299<td> 300 <p> 301</p> 302<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span> 303<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> 304<p> 305 </p> 306 </td> 307</tr> 308<tr> 309<td> 310 <p> 311 <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> 312 <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> 313 </p> 314 </td> 315<td> 316 <p> 317</p> 318<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span> 319<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> 320<p> 321 </p> 322 </td> 323</tr> 324</tbody> 325</table></div> 326<div class="important"><table border="0" summary="Important"> 327<tr> 328<td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../images/important.png"></td> 329<th align="left">Important</th> 330</tr> 331<tr><td align="left" valign="top"> 332<p> 333 The table above uses <code class="computeroutput"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span></code> as placeholders only. 334 </p> 335<p> 336 The notation of <code class="computeroutput"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">A</span><span class="special">></span></code> stands for <span class="emphasis"><em>any STL container</em></span> 337 holding elements of type <code class="computeroutput"><span class="identifier">A</span></code>. 338 </p> 339</td></tr> 340</table></div> 341<p> 342 It is important to note, that the <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> directive does not perform any buffering 343 of the output generated by its embedded elements. That means that any 344 failing element generator might have already generated some output, which 345 is <span class="emphasis"><em>not</em></span> rolled back. 346 </p> 347<div class="tip"><table border="0" summary="Tip"> 348<tr> 349<td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../images/tip.png"></td> 350<th align="left">Tip</th> 351</tr> 352<tr><td align="left" valign="top"> 353<p> 354 The simplest way to force a <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> directive to behave as if it did 355 buffering is to wrap it into a buffering directive (see <a class="link" href="buffer.html" title="Generator Directive for Temporary Output Buffering (buffer[])"><code class="computeroutput"><span class="identifier">buffer</span></code></a>): 356 </p> 357<p> 358</p> 359<pre class="programlisting"><span class="identifier">buffer</span><span class="special">[</span><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]]</span></pre> 360<p> 361 </p> 362<p> 363 which will <span class="emphasis"><em>not</em></span> generate any output in case of 364 a failing generator <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>. The expression: 365 </p> 366<p> 367</p> 368<pre class="programlisting"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">buffer</span><span class="special">[</span><span class="identifier">a</span><span class="special">]]</span></pre> 369<p> 370 </p> 371<p> 372 will not generate any partial output from a generator <code class="computeroutput"><span class="identifier">a</span></code> if it fails generating in the middle 373 of its output. The overall expression will still generate the output 374 as produced by all succeeded invocations of the generator <code class="computeroutput"><span class="identifier">a</span></code>. 375 </p> 376</td></tr> 377</table></div> 378<h6> 379<a name="spirit.karma.reference.directive.repeat.h6"></a> 380 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.complexity"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.complexity">Complexity</a> 381 </h6> 382<div class="blockquote"><blockquote class="blockquote"><p> 383 The overall complexity of the repetition generator is defined by the 384 complexity of its embedded generator. The complexity of the repeat 385 itself is O(N), where N is the number of repetitions to execute. 386 </p></blockquote></div> 387<h6> 388<a name="spirit.karma.reference.directive.repeat.h7"></a> 389 <span class="phrase"><a name="spirit.karma.reference.directive.repeat.example"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.example">Example</a> 390 </h6> 391<div class="note"><table border="0" summary="Note"> 392<tr> 393<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 394<th align="left">Note</th> 395</tr> 396<tr><td align="left" valign="top"><p> 397 The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.karma.reference.basics.examples">Basics Examples</a> 398 section. 399 </p></td></tr> 400</table></div> 401<p> 402 Some includes: 403 </p> 404<p> 405</p> 406<pre class="programlisting"><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">karma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 407<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">support_utree</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 408<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">phoenix_core</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 409<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">phoenix_operator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 410<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">std_pair</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 411<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 412<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> 413</pre> 414<p> 415 </p> 416<p> 417 Some using declarations: 418 </p> 419<p> 420</p> 421<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">karma</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> 422<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">karma</span><span class="special">::</span><span class="identifier">repeat</span><span class="special">;</span> 423</pre> 424<p> 425 </p> 426<p> 427 Basic usage of <code class="computeroutput"><span class="identifier">repeat</span></code> 428 generator directive: 429 </p> 430<p> 431</p> 432<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">v</span><span class="special">;</span> 433<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">1.0</span><span class="special">);</span> 434<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span> 435<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">3.0</span><span class="special">);</span> 436 437<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"[1.0][2.0][3.0]"</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">[</span><span class="char">'['</span> <span class="special"><<</span> <span class="identifier">double_</span> <span class="special"><<</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span> 438<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"[1.0][2.0]"</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">(</span><span class="number">2</span><span class="special">)[</span><span class="char">'['</span> <span class="special"><<</span> <span class="identifier">double_</span> <span class="special"><<</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span> 439 440<span class="comment">// fails because of insufficient number of items</span> 441<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">""</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">(</span><span class="number">4</span><span class="special">)[</span><span class="char">'['</span> <span class="special"><<</span> <span class="identifier">double_</span> <span class="special"><<</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span> 442</pre> 443<p> 444 </p> 445</div> 446<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 447<td align="left"></td> 448<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p> 449 Distributed under the Boost Software License, Version 1.0. (See accompanying 450 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>) 451 </p> 452</div></td> 453</tr></table> 454<hr> 455<div class="spirit-nav"> 456<a accesskey="p" href="alignment.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.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="delimit.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 457</div> 458</body> 459</html> 460
