1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Real Number Generators (float_, double_, etc.)</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="../numeric.html" title="Numeric Generators"> 9<link rel="prev" href="signed_int.html" title="Signed Integer Number Generators (int_, etc.)"> 10<link rel="next" href="boolean.html" title="Boolean Generators (bool_)"> 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="signed_int.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../numeric.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="boolean.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.numeric.real_number"></a><a class="link" href="real_number.html" title="Real Number Generators (float_, double_, etc.)">Real 28 Number Generators (<code class="computeroutput"><span class="identifier">float_</span></code>, 29 <code class="computeroutput"><span class="identifier">double_</span></code>, etc.)</a> 30</h5></div></div></div> 31<h6> 32<a name="spirit.karma.reference.numeric.real_number.h0"></a> 33 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.description"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.description">Description</a> 34 </h6> 35<p> 36 The <code class="computeroutput"><span class="identifier">real_generator</span></code> can 37 generate real numbers of arbitrary length and size limited by its template 38 parameter, <code class="computeroutput"><span class="identifier">Num</span></code>. The numeric 39 base type <code class="computeroutput"><span class="identifier">Num</span></code> can be 40 a user defined numeric type such as fixed_point (fixed point reals) and 41 bignum (unlimited precision numbers) if the type follows certain expression 42 requirements (for more information about the requirements, see <a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.additional_requirements">below</a>). 43 </p> 44<h6> 45<a name="spirit.karma.reference.numeric.real_number.h1"></a> 46 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.header"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.header">Header</a> 47 </h6> 48<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/numeric/real.hpp></span> 49<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_real</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 50</pre> 51<p> 52 Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. 53 </p> 54<h6> 55<a name="spirit.karma.reference.numeric.real_number.h2"></a> 56 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.namespace"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.namespace">Namespace</a> 57 </h6> 58<div class="informaltable"><table class="table"> 59<colgroup><col></colgroup> 60<thead><tr><th> 61 <p> 62 Name 63 </p> 64 </th></tr></thead> 65<tbody> 66<tr><td> 67 <p> 68 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">lit</span> <span class="comment">// alias: 69 boost::spirit::karma::lit</span></code> 70 </p> 71 </td></tr> 72<tr><td> 73 <p> 74 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">float_</span> <span class="comment">// 75 alias: boost::spirit::karma::float_</span></code> 76 </p> 77 </td></tr> 78<tr><td> 79 <p> 80 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">double_</span> <span class="comment">// 81 alias: boost::spirit::karma::double_</span></code> 82 </p> 83 </td></tr> 84<tr><td> 85 <p> 86 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">long_double</span> <span class="comment">// 87 alias: boost::spirit::karma::long_double</span></code> 88 </p> 89 </td></tr> 90</tbody> 91</table></div> 92<div class="note"><table border="0" summary="Note"> 93<tr> 94<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 95<th align="left">Note</th> 96</tr> 97<tr><td align="left" valign="top"><p> 98 <code class="computeroutput"><span class="identifier">lit</span></code> is reused by the 99 <a class="link" href="../string.html" title="String Generators">String Generators</a>, 100 the <a class="link" href="../char.html" title="Char Generators">Character Generators</a>, 101 and the Numeric Generators. In general, a char generator is created 102 when you pass in a character, a string generator is created when you 103 pass in a string, and a numeric generator is created when you use a 104 numeric literal. 105 </p></td></tr> 106</table></div> 107<h6> 108<a name="spirit.karma.reference.numeric.real_number.h3"></a> 109 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.synopsis"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.synopsis">Synopsis</a> 110 </h6> 111<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Num</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">RealPolicies</span><span class="special">></span> 112<span class="keyword">struct</span> <span class="identifier">real_generator</span><span class="special">;</span> 113</pre> 114<h6> 115<a name="spirit.karma.reference.numeric.real_number.h4"></a> 116 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.template_parameters"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.template_parameters">Template 117 parameters</a> 118 </h6> 119<div class="informaltable"><table class="table"> 120<colgroup> 121<col> 122<col> 123<col> 124</colgroup> 125<thead><tr> 126<th> 127 <p> 128 Parameter 129 </p> 130 </th> 131<th> 132 <p> 133 Description 134 </p> 135 </th> 136<th> 137 <p> 138 Default 139 </p> 140 </th> 141</tr></thead> 142<tbody> 143<tr> 144<td> 145 <p> 146 <code class="computeroutput"><span class="identifier">Num</span></code> 147 </p> 148 </td> 149<td> 150 <p> 151 The type of the real number to generate. 152 </p> 153 </td> 154<td> 155 <p> 156 <code class="computeroutput"><span class="keyword">double</span></code> 157 </p> 158 </td> 159</tr> 160<tr> 161<td> 162 <p> 163 <code class="computeroutput"><span class="identifier">RealPolicies</span></code> 164 </p> 165 </td> 166<td> 167 <p> 168 The policies to use while converting the real number. 169 </p> 170 </td> 171<td> 172 <p> 173 <code class="computeroutput"><span class="identifier">real_policies</span><span class="special"><</span><span class="identifier">Num</span><span class="special">></span></code> 174 </p> 175 </td> 176</tr> 177</tbody> 178</table></div> 179<p> 180 For more information about the type <code class="computeroutput"><span class="identifier">RealPolicies</span></code> 181 see <a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.real_number_formatting_policies">below</a>. 182 </p> 183<h6> 184<a name="spirit.karma.reference.numeric.real_number.h5"></a> 185 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.model_of"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.model_of">Model of</a> 186 </h6> 187<div class="blockquote"><blockquote class="blockquote"><p> 188 <a class="link" href="../generator_concepts/primitivegenerator.html" title="PrimitiveGenerator"><code class="computeroutput"><span class="identifier">PrimitiveGenerator</span></code></a> 189 </p></blockquote></div> 190<div class="variablelist"> 191<p class="title"><b>Notation</b></p> 192<dl class="variablelist"> 193<dt><span class="term"><code class="computeroutput"><span class="identifier">num</span></code></span></dt> 194<dd><p> 195 Numeric literal, any real number value, or a <a class="link" href="../basics.html#spirit.karma.reference.basics.lazy_argument">Lazy 196 Argument</a> that evaluates to a real number value of type 197 <code class="computeroutput"><span class="identifier">Num</span></code> 198 </p></dd> 199<dt><span class="term"><code class="computeroutput"><span class="identifier">Num</span></code></span></dt> 200<dd><p> 201 Type of <code class="computeroutput"><span class="identifier">num</span></code>: any 202 real number type 203 </p></dd> 204</dl> 205</div> 206<h6> 207<a name="spirit.karma.reference.numeric.real_number.h6"></a> 208 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.expression_semantics"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.expression_semantics">Expression 209 Semantics</a> 210 </h6> 211<p> 212 Semantics of an expression is defined only where it differs from, or 213 is not defined in <a class="link" href="../generator_concepts/primitivegenerator.html" title="PrimitiveGenerator"><code class="computeroutput"><span class="identifier">PrimitiveGenerator</span></code></a>. 214 </p> 215<div class="informaltable"><table class="table"> 216<colgroup> 217<col> 218<col> 219</colgroup> 220<thead><tr> 221<th> 222 <p> 223 Expression 224 </p> 225 </th> 226<th> 227 <p> 228 Semantics 229 </p> 230 </th> 231</tr></thead> 232<tbody> 233<tr> 234<td> 235 <p> 236 <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code> 237 </p> 238 </td> 239<td> 240 <p> 241 Generate the real number literal <code class="computeroutput"><span class="identifier">num</span></code> 242 using the default formatting (no trailing zeros, <code class="computeroutput"><span class="identifier">fixed</span></code> representation for 243 numbers <code class="computeroutput"><span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> <span class="special"><=</span> 244 <span class="number">1e5</span> <span class="special">&&</span> 245 <span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> 246 <span class="special">></span> <span class="number">1e-3</span></code>, 247 scientific representation otherwise, 3 fractional digits, sign 248 is only printed for negative literals). This generator never 249 fails (unless the underlying output stream reports an error). 250 </p> 251 </td> 252</tr> 253<tr> 254<td> 255 <p> 256</p> 257<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">float_</span> 258<span class="identifier">double_</span> 259<span class="identifier">long_double</span></pre> 260<p> 261 </p> 262 </td> 263<td> 264 <p> 265 Generate the real number provided by a mandatory attribute 266 using the default formatting (no trailing zeros, <code class="computeroutput"><span class="identifier">fixed</span></code> representation for 267 numbers <code class="computeroutput"><span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> <span class="special"><=</span> 268 <span class="number">1e5</span> <span class="special">&&</span> 269 <span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> 270 <span class="special">></span> <span class="number">1e-3</span></code>, 271 scientific representation otherwise, 3 fractional digits, sign 272 is only printed for negative literals). This generator never 273 fails (unless the underlying output stream reports an error). 274 </p> 275 </td> 276</tr> 277<tr> 278<td> 279 <p> 280</p> 281<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">float_</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span> 282<span class="identifier">double_</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span> 283<span class="identifier">long_double</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></pre> 284<p> 285 </p> 286 </td> 287<td> 288 <p> 289 Generate the real point number provided by the immediate literal 290 value the generator is initialized from using the default formatting 291 (no trailing zeros, <code class="computeroutput"><span class="identifier">fixed</span></code> 292 representation for numbers <code class="computeroutput"><span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> <span class="special"><=</span> 293 <span class="number">1e5</span> <span class="special">&&</span> 294 <span class="identifier">fabs</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span> 295 <span class="special">></span> <span class="number">1e-3</span></code>, 296 scientific representation otherwise, 3 fractional digits, sign 297 is only printed for negative literals). If this generator has 298 an associated attribute it succeeds only if the attribute is 299 equal to the immediate literal (unless the underlying output 300 stream reports an error). Otherwise this generator fails and 301 does not generate any output. 302 </p> 303 </td> 304</tr> 305</tbody> 306</table></div> 307<p> 308 All generators listed in the table above (except <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code>) are predefined specializations of the 309 <code class="computeroutput"><span class="identifier">real_generator</span><span class="special"><</span><span class="identifier">Num</span><span class="special">,</span> <span class="identifier">RealPolicies</span><span class="special">></span></code> 310 basic real number generator type described below. It is possible to directly 311 use this type to create real number generators using a wide range of 312 formatting options. 313 </p> 314<div class="informaltable"><table class="table"> 315<colgroup> 316<col> 317<col> 318</colgroup> 319<thead><tr> 320<th> 321 <p> 322 Expression 323 </p> 324 </th> 325<th> 326 <p> 327 Semantics 328 </p> 329 </th> 330</tr></thead> 331<tbody> 332<tr> 333<td> 334 <p> 335</p> 336<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">real_generator</span><span class="special"><</span> 337 <span class="identifier">Num</span><span class="special">,</span> <span class="identifier">RealPolicies</span> 338<span class="special">>()</span></pre> 339<p> 340 </p> 341 </td> 342<td> 343 <p> 344 Generate the real number of type <code class="computeroutput"><span class="identifier">Num</span></code> 345 provided by a mandatory attribute using the specified <code class="computeroutput"><span class="identifier">RealPolicies</span></code>. This generator 346 never fails (unless the underlying output stream reports an 347 error). 348 </p> 349 </td> 350</tr> 351<tr> 352<td> 353 <p> 354</p> 355<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">real_generator</span><span class="special"><</span> 356 <span class="identifier">Num</span><span class="special">,</span> <span class="identifier">RealPolicies</span> 357<span class="special">>()(</span><span class="identifier">num</span><span class="special">)</span></pre> 358<p> 359 </p> 360 </td> 361<td> 362 <p> 363 Generate the real number of type <code class="computeroutput"><span class="identifier">Num</span></code> 364 provided by the immediate literal value the generator is initialized 365 from using the specified <code class="computeroutput"><span class="identifier">RealPolicies</span></code>. 366 If this generator has an associated attribute it succeeds only 367 if the attribute is equal to the immediate literal (unless 368 the underlying output stream reports an error). Otherwise this 369 generator fails and does not generate any output. 370 </p> 371 </td> 372</tr> 373</tbody> 374</table></div> 375<h6> 376<a name="spirit.karma.reference.numeric.real_number.h7"></a> 377 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.additional_requirements"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.additional_requirements">Additional 378 Requirements</a> 379 </h6> 380<p> 381 The following list enumerates the requirements which must be met in order 382 to use a certain type <code class="computeroutput"><span class="identifier">Num</span></code> 383 to instantiate a <code class="computeroutput"><span class="identifier">real_generator</span><span class="special"><</span><span class="identifier">Num</span><span class="special">,</span> <span class="identifier">Policies</span><span class="special">></span></code>. 384 </p> 385<p> 386 In order to be usable as the first template parameter for <code class="computeroutput"><span class="identifier">real_generator</span><span class="special"><></span></code> 387 the type <code class="computeroutput"><span class="identifier">Num</span></code> must have 388 defined: 389 </p> 390<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 391<li class="listitem"> 392 comparison operators for: <code class="computeroutput"><span class="special"><</span></code>, 393 <code class="computeroutput"><span class="special"><=</span></code>, <code class="computeroutput"><span class="special">==</span></code>, <code class="computeroutput"><span class="special">!=</span></code>, 394 <code class="computeroutput"><span class="special">></span></code>, and <code class="computeroutput"><span class="special">>=</span></code> 395 </li> 396<li class="listitem"> 397 numeric operators for: <code class="computeroutput"><span class="special">+</span></code>, 398 <code class="computeroutput"><span class="special">-</span></code>, <code class="computeroutput"><span class="special">/</span></code>, 399 <code class="computeroutput"><span class="special">*</span></code>, and <code class="computeroutput"><span class="special">%</span></code> 400 </li> 401<li class="listitem"> 402 functions implementing the interface and the semantics of: <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">fmod</span></code>, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pow</span></code>, 403 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">log10</span></code>, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">lround</span></code>, 404 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ltrunc</span></code>, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">modf</span></code>, 405 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">floor</span></code>, and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ceil</span></code>. 406 These need to be defined in a way so that they will be found using 407 argument dependent lookup (ADL). 408 </li> 409<li class="listitem"> 410 a valid specialization of the type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special"><</span><span class="identifier">Num</span><span class="special">></span></code> allowing for numeric property 411 inspection. 412 </li> 413</ul></div> 414<h6> 415<a name="spirit.karma.reference.numeric.real_number.h8"></a> 416 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.attributes"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.attributes">Attributes</a> 417 </h6> 418<div class="informaltable"><table class="table"> 419<colgroup> 420<col> 421<col> 422</colgroup> 423<thead><tr> 424<th> 425 <p> 426 Expression 427 </p> 428 </th> 429<th> 430 <p> 431 Attribute 432 </p> 433 </th> 434</tr></thead> 435<tbody> 436<tr> 437<td> 438 <p> 439 <code class="computeroutput"><span class="identifier">lit</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code> 440 </p> 441 </td> 442<td> 443 <p> 444 <code class="computeroutput"><span class="identifier">unused</span></code> 445 </p> 446 </td> 447</tr> 448<tr> 449<td> 450 <p> 451 <code class="computeroutput"><span class="identifier">float_</span></code> 452 </p> 453 </td> 454<td> 455 <p> 456 <code class="computeroutput"><span class="keyword">float</span></code>, attribute 457 is mandatory (otherwise compilation will fail) 458 </p> 459 </td> 460</tr> 461<tr> 462<td> 463 <p> 464 <code class="computeroutput"><span class="identifier">float_</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code> 465 </p> 466 </td> 467<td> 468 <p> 469 <code class="computeroutput"><span class="identifier">float_</span></code>, attribute 470 is optional, if it is supplied, the generator compares the 471 attribute with <code class="computeroutput"><span class="identifier">num</span></code> 472 and succeeds only if both are equal, failing otherwise. 473 </p> 474 </td> 475</tr> 476<tr> 477<td> 478 <p> 479 <code class="computeroutput"><span class="identifier">double_</span></code> 480 </p> 481 </td> 482<td> 483 <p> 484 <code class="computeroutput"><span class="keyword">double</span></code>, attribute 485 is mandatory (otherwise compilation will fail) 486 </p> 487 </td> 488</tr> 489<tr> 490<td> 491 <p> 492 <code class="computeroutput"><span class="identifier">double_</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code> 493 </p> 494 </td> 495<td> 496 <p> 497 <code class="computeroutput"><span class="keyword">double</span></code>, attribute 498 is optional, if it is supplied, the generator compares the 499 attribute with <code class="computeroutput"><span class="identifier">num</span></code> 500 and succeeds only if both are equal, failing otherwise. 501 </p> 502 </td> 503</tr> 504<tr> 505<td> 506 <p> 507 <code class="computeroutput"><span class="identifier">long_double</span></code> 508 </p> 509 </td> 510<td> 511 <p> 512 <code class="computeroutput"><span class="keyword">long</span> <span class="keyword">double</span></code>, 513 attribute is mandatory (otherwise compilation will fail) 514 </p> 515 </td> 516</tr> 517<tr> 518<td> 519 <p> 520 <code class="computeroutput"><span class="identifier">long_double</span><span class="special">(</span><span class="identifier">num</span><span class="special">)</span></code> 521 </p> 522 </td> 523<td> 524 <p> 525 <code class="computeroutput"><span class="keyword">long</span> <span class="keyword">double</span></code>, 526 attribute is optional, if it is supplied, the generator compares 527 the attribute with <code class="computeroutput"><span class="identifier">num</span></code> 528 and succeeds only if both are equal, failing otherwise. 529 </p> 530 </td> 531</tr> 532<tr> 533<td> 534 <p> 535</p> 536<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">real_generator</span><span class="special"><</span> 537 <span class="identifier">Num</span><span class="special">,</span> <span class="identifier">Policies</span> 538<span class="special">>()</span></pre> 539<p> 540 </p> 541 </td> 542<td> 543 <p> 544 <code class="computeroutput"><span class="identifier">Num</span></code>, attribute 545 is mandatory (otherwise compilation will fail) 546 </p> 547 </td> 548</tr> 549<tr> 550<td> 551 <p> 552</p> 553<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">real_generator</span><span class="special"><</span> 554 <span class="identifier">Num</span><span class="special">,</span> <span class="identifier">Policies</span> 555<span class="special">>()(</span><span class="identifier">num</span><span class="special">)</span></pre> 556<p> 557 </p> 558 </td> 559<td> 560 <p> 561 <code class="computeroutput"><span class="identifier">Num</span></code>, attribute 562 is optional, if it is supplied, the generator compares the 563 attribute with <code class="computeroutput"><span class="identifier">num</span></code> 564 and succeeds only if both are equal, failing otherwise. 565 </p> 566 </td> 567</tr> 568</tbody> 569</table></div> 570<div class="note"><table border="0" summary="Note"> 571<tr> 572<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 573<th align="left">Note</th> 574</tr> 575<tr><td align="left" valign="top"><p> 576 In addition to their usual attribute of type <code class="computeroutput"><span class="identifier">Num</span></code> 577 all listed generators accept an instance of a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special"><</span><span class="identifier">Num</span><span class="special">></span></code> as well. If the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special"><></span></code> is initialized (holds a value) 578 the generators behave as if their attribute was an instance of <code class="computeroutput"><span class="identifier">Num</span></code> and emit the value stored in 579 the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special"><></span></code>. 580 Otherwise the generators will fail. 581 </p></td></tr> 582</table></div> 583<h6> 584<a name="spirit.karma.reference.numeric.real_number.h9"></a> 585 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.real_number_formatting_policies"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.real_number_formatting_policies">Real 586 Number Formatting Policies</a> 587 </h6> 588<p> 589 If special formatting of a real number is needed, overload the policy 590 class <code class="computeroutput"><span class="identifier">real_policies</span><span class="special"><</span><span class="identifier">Num</span><span class="special">></span></code> 591 and use it as a template parameter to the <code class="computeroutput"><span class="identifier">real_generator</span><span class="special"><></span></code> real number generator. For instance: 592 </p> 593<pre class="programlisting"><span class="comment">// define a new real number formatting policy</span> 594<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Num</span><span class="special">></span> 595<span class="keyword">struct</span> <span class="identifier">scientific_policy</span> <span class="special">:</span> <span class="identifier">real_policies</span><span class="special"><</span><span class="identifier">Num</span><span class="special">></span> 596<span class="special">{</span> 597 <span class="comment">// we want the numbers always to be in scientific format</span> 598 <span class="keyword">static</span> <span class="keyword">int</span> <span class="identifier">floatfield</span><span class="special">(</span><span class="identifier">Num</span> <span class="identifier">n</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">fmtflags</span><span class="special">::</span><span class="identifier">scientific</span><span class="special">;</span> <span class="special">}</span> 599<span class="special">};</span> 600 601<span class="comment">// define a new generator type based on the new policy</span> 602<span class="keyword">typedef</span> <span class="identifier">real_generator</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="identifier">scientific_policy</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="special">></span> <span class="identifier">science_type</span><span class="special">;</span> 603<span class="identifier">science_type</span> <span class="keyword">const</span> <span class="identifier">scientific</span> <span class="special">=</span> <span class="identifier">science_type</span><span class="special">();</span> 604 605<span class="comment">// use the new generator </span> 606<span class="identifier">generate</span><span class="special">(</span><span class="identifier">sink</span><span class="special">,</span> <span class="identifier">science_type</span><span class="special">(),</span> <span class="number">1.0</span><span class="special">);</span> <span class="comment">// will output: 1.0e00</span> 607<span class="identifier">generate</span><span class="special">(</span><span class="identifier">sink</span><span class="special">,</span> <span class="identifier">scientific</span><span class="special">,</span> <span class="number">0.1</span><span class="special">);</span> <span class="comment">// will output: 1.0e-01</span> 608</pre> 609<p> 610 The template parameter <code class="computeroutput"><span class="identifier">Num</span></code> 611 should be the type to be formatted using the overloaded policy type. 612 At the same time <code class="computeroutput"><span class="identifier">Num</span></code> 613 will be used as the attribute type of the created real number generator. 614 </p> 615<h6> 616<a name="spirit.karma.reference.numeric.real_number.h10"></a> 617 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.real_number_formatting_policy_expression_semantics"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.real_number_formatting_policy_expression_semantics">Real 618 Number Formatting Policy Expression Semantics</a> 619 </h6> 620<p> 621 A real number formatting policy should expose the following variables 622 and functions: 623 </p> 624<div class="informaltable"><table class="table"> 625<colgroup> 626<col> 627<col> 628</colgroup> 629<thead><tr> 630<th> 631 <p> 632 Expression 633 </p> 634 </th> 635<th> 636 <p> 637 Description 638 </p> 639 </th> 640</tr></thead> 641<tbody> 642<tr> 643<td> 644 <p> 645</p> 646<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">Inserter</span> 647 <span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span> 648 <span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Policies</span><span class="special">></span> 649<span class="keyword">bool</span> <span class="identifier">call</span> <span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span> 650 <span class="special">,</span> <span class="identifier">Policies</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">p</span><span class="special">);</span> 651</pre> 652<p> 653 </p> 654 </td> 655<td> 656 <p> 657 This is the main function used to generate the output for a 658 real number. It is called by the real generator in order to 659 perform the conversion. In theory all of the work can be implemented 660 here, but the easiest way is to use existing functionality 661 provided by the type specified by the template parameter <code class="computeroutput"><span class="identifier">Inserter</span></code>. The default implementation 662 of this functions is: 663</p> 664<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">Inserter</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span> 665 <span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Policies</span><span class="special">></span> 666<span class="keyword">static</span> <span class="keyword">bool</span> 667<span class="identifier">call</span> <span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">Policies</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">p</span><span class="special">)</span> 668<span class="special">{</span> 669 <span class="keyword">return</span> <span class="identifier">Inserter</span><span class="special">::</span><span class="identifier">call_n</span><span class="special">(</span><span class="identifier">sink</span><span class="special">,</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">p</span><span class="special">);</span> 670<span class="special">}</span> 671</pre> 672<p> 673 <code class="computeroutput"><span class="identifier">sink</span></code> is the 674 output iterator to use for generation 675 </p> 676 <p> 677 <code class="computeroutput"><span class="identifier">n</span></code> is the real 678 number to convert 679 </p> 680 <p> 681 <code class="computeroutput"><span class="identifier">p</span></code> is the instance 682 of the policy type used to instantiate this real number generator. 683 </p> 684 </td> 685</tr> 686<tr> 687<td> 688 <p> 689</p> 690<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">bool</span> <span class="identifier">force_sign</span><span class="special">(</span><span class="identifier">Num</span> <span class="identifier">n</span><span class="special">);</span> 691</pre> 692<p> 693 </p> 694 </td> 695<td> 696 <p> 697 The default behavior is to not to require generating a sign. 698 If the function <code class="computeroutput"><span class="identifier">force_sign</span><span class="special">()</span></code> returns true, then all generated 699 numbers will have a sign (<code class="computeroutput"><span class="char">'+'</span></code> 700 or <code class="computeroutput"><span class="char">'-'</span></code>, zeros will 701 have a space instead of a sign). 702 </p> 703 <p> 704 <code class="computeroutput"><span class="identifier">n</span></code> is the real 705 number to output. This can be used to adjust the required behavior 706 depending on the value of this number. 707 </p> 708 </td> 709</tr> 710<tr> 711<td> 712 <p> 713</p> 714<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">bool</span> <span class="identifier">trailing_zeros</span><span class="special">(</span><span class="identifier">Num</span> <span class="identifier">n</span><span class="special">);</span> 715</pre> 716<p> 717 </p> 718 </td> 719<td> 720 <p> 721 Return whether trailing zero digits have to be emitted in the 722 fractional part of the output. If set, this flag instructs 723 the real number generator to emit trailing zeros up to the 724 required precision digits (as returned by the <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> 725 function). 726 </p> 727 <p> 728 <code class="computeroutput"><span class="identifier">n</span></code> is the real 729 number to output. This can be used to adjust the required behavior 730 depending on the value of this number. 731 </p> 732 </td> 733</tr> 734<tr> 735<td> 736 <p> 737</p> 738<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">int</span> <span class="identifier">floatfield</span><span class="special">(</span><span class="identifier">Num</span> <span class="identifier">n</span><span class="special">);</span> 739</pre> 740<p> 741 </p> 742 </td> 743<td> 744 <p> 745 Decide, which representation type to use in the generated output. 746 </p> 747 <p> 748 By default all numbers having an absolute value of zero or 749 in between <code class="computeroutput"><span class="number">0.001</span></code> 750 and <code class="computeroutput"><span class="number">100000</span></code> will 751 be generated using the fixed format, all others will be generated 752 using the scientific representation. 753 </p> 754 <p> 755 The <code class="computeroutput"><span class="identifier">trailing_zeros</span><span class="special">()</span></code> can be used to force the 756 output of trailing zeros in the fractional part up to the number 757 of digits returned by the <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> member function. The default 758 is not to generate the trailing zeros. 759 </p> 760 <p> 761 <code class="computeroutput"><span class="identifier">n</span></code> is the real 762 number to output. This can be used to adjust the formatting 763 flags depending on the value of this number. 764 </p> 765 <p> 766 The return value has to be either <code class="computeroutput"><span class="identifier">fmtflags</span><span class="special">::</span><span class="identifier">scientific</span></code> 767 (generate real number values in scientific notation) or <code class="computeroutput"><span class="identifier">fmtflags</span><span class="special">::</span><span class="identifier">fixed</span></code> (generate real number 768 values in fixed-point notation). 769 </p> 770 </td> 771</tr> 772<tr> 773<td> 774 <p> 775</p> 776<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">unsigned</span> <span class="identifier">precision</span><span class="special">(</span><span class="identifier">Num</span> <span class="identifier">n</span><span class="special">);</span> 777</pre> 778<p> 779 </p> 780 </td> 781<td> 782 <p> 783 Return the maximum number of decimal digits to generate in 784 the fractional part of the output. 785 </p> 786 <p> 787 <code class="computeroutput"><span class="identifier">n</span></code> is the real 788 number to output. This can be used to adjust the required precision 789 depending on the value of this number. If the trailing zeros 790 flag is specified the fractional part of the output will be 791 'filled' with zeros, if appropriate. 792 </p> 793 <p> 794 <span class="bold"><strong>Note:</strong></span> If the trailing_zeros 795 flag is not in effect additional semantics apply. See the description 796 for the <code class="computeroutput"><span class="identifier">fraction_part</span><span class="special">()</span></code> function below. Moreover, 797 this precision will be limited to the value of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">digits10</span> <span class="special">+</span> 798 <span class="number">1</span></code>. 799 </p> 800 </td> 801</tr> 802<tr> 803<td> 804 <p> 805</p> 806<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">OutputIterator</span><span class="special">></span> 807<span class="keyword">bool</span> <span class="identifier">integer_part</span><span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span> 808 <span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span><span class="special">,</span> <span class="keyword">bool</span> <span class="identifier">sign</span><span class="special">,</span> <span class="keyword">bool</span> <span class="identifier">force_sign</span><span class="special">);</span> 809</pre> 810<p> 811 </p> 812 </td> 813<td> 814 <p> 815 This function is called to generate the integer part of the 816 real number. 817 </p> 818 <p> 819 <code class="computeroutput"><span class="identifier">sink</span></code> is the 820 output iterator to use for generation 821 </p> 822 <p> 823 <code class="computeroutput"><span class="identifier">n</span></code> is the absolute 824 value of the integer part of the real number to convert (always 825 non-negative) 826 </p> 827 <p> 828 <code class="computeroutput"><span class="identifier">sign</span></code> is the 829 sign of the overall real number to convert. 830 </p> 831 <p> 832 <code class="computeroutput"><span class="identifier">force_sign</span></code> 833 is a flag indicating whether a sign has to be generated even 834 for non-negative numbers (this is the same as has been returned 835 from the function <code class="computeroutput"><span class="identifier">force_sign</span><span class="special">()</span></code> described above) 836 </p> 837 <p> 838 The return value defines the outcome of the whole generator. 839 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 840 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 841 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 842 output generation continues. 843 </p> 844 </td> 845</tr> 846<tr> 847<td> 848 <p> 849</p> 850<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">OutputIterator</span><span class="special">></span> 851<span class="keyword">bool</span> <span class="identifier">dot</span><span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span><span class="special">,</span> 852 <span class="keyword">unsigned</span> <span class="identifier">precision</span><span class="special">);</span> 853</pre> 854<p> 855 </p> 856 </td> 857<td> 858 <p> 859 This function is called to generate the decimal point. 860 </p> 861 <p> 862 <code class="computeroutput"><span class="identifier">sink</span></code> is the 863 output iterator to use for generation 864 </p> 865 <p> 866 <code class="computeroutput"><span class="identifier">n</span></code> is the fractional 867 part of the real number to convert. Note that this number is 868 scaled such, that it represents the number of units which correspond 869 to the value returned from the <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> function earlier. I.e. a 870 fractional part of <code class="computeroutput"><span class="number">0.01234</span></code> 871 is represented as <code class="computeroutput"><span class="number">1234</span></code> 872 when the function <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> returned <code class="computeroutput"><span class="number">5</span></code>. 873 </p> 874 <p> 875 <code class="computeroutput"><span class="identifier">precision</span></code> is 876 the number of digits to emit as returned by the function <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> 877 described above 878 </p> 879 <p> 880 This is given to allow to decide, whether a decimal point has 881 to be generated at all. 882 </p> 883 <p> 884 <span class="bold"><strong>Note:</strong></span> If the <code class="computeroutput"><span class="identifier">trailing_zeros</span></code> flag is not 885 in effect additional comments apply. See the description for 886 the <code class="computeroutput"><span class="identifier">fraction_part</span><span class="special">()</span></code> function below. 887 </p> 888 <p> 889 The return value defines the outcome of the whole generator. 890 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 891 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 892 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 893 output generation continues. 894 </p> 895 </td> 896</tr> 897<tr> 898<td> 899 <p> 900</p> 901<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">OutputIterator</span><span class="special">></span> 902<span class="keyword">bool</span> <span class="identifier">fraction_part</span><span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span> 903 <span class="special">,</span> <span class="keyword">unsigned</span> <span class="identifier">adjprec</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="identifier">precision</span><span class="special">);</span> 904</pre> 905<p> 906 </p> 907 </td> 908<td> 909 <p> 910 This function is called to generate the fractional part of 911 the number. 912 </p> 913 <p> 914 <code class="computeroutput"><span class="identifier">sink</span></code> is the 915 output iterator to use for generation 916 </p> 917 <p> 918 <code class="computeroutput"><span class="identifier">n</span></code> is the fractional 919 part of the real number to convert. Note that this number is 920 scaled such, that it represents the number of units which correspond 921 to the value returned from the <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> function earlier. I.e. a 922 fractional part of <code class="computeroutput"><span class="number">0.01234</span></code> 923 is represented as <code class="computeroutput"><span class="number">1234</span></code> 924 when the function <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> returned <code class="computeroutput"><span class="number">5</span></code>. 925 </p> 926 <p> 927 <code class="computeroutput"><span class="identifier">adjprec</span></code> is 928 the corrected number of digits to emit (see note below) 929 </p> 930 <p> 931 <code class="computeroutput"><span class="identifier">precision</span></code> is 932 the number of digits to emit as returned by the function <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> 933 described above 934 </p> 935 <p> 936 <span class="bold"><strong>Note:</strong></span> If <code class="computeroutput"><span class="identifier">trailing_zeros</span><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code> 937 the <code class="computeroutput"><span class="identifier">adjprec</span></code> 938 parameter will have been corrected from the value the <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> 939 function returned earlier (defining the maximal number of fractional 940 digits) in the sense, that it takes into account trailing zeros. 941 I.e. a real number <code class="computeroutput"><span class="number">0.0123</span></code> 942 and a value of <code class="computeroutput"><span class="number">5</span></code> 943 returned from <code class="computeroutput"><span class="identifier">precision</span><span class="special">()</span></code> will result in: 944 </p> 945 <p> 946 <code class="computeroutput"><span class="identifier">trailing_zeros</span><span class="special">()</span></code> returned <code class="computeroutput"><span class="keyword">false</span></code>: 947 <code class="computeroutput"><span class="identifier">n</span></code> will be 948 <code class="computeroutput"><span class="number">123</span></code>, and <code class="computeroutput"><span class="identifier">adjprec</span></code> will be <code class="computeroutput"><span class="number">4</span></code> (as we need to print <code class="computeroutput"><span class="number">0123</span></code>) 949 </p> 950 <p> 951 <code class="computeroutput"><span class="identifier">trailing_zeros</span><span class="special">()</span></code> returned <code class="computeroutput"><span class="keyword">true</span></code>: 952 <code class="computeroutput"><span class="identifier">n</span></code> will be 953 <code class="computeroutput"><span class="number">1230</span></code>, and <code class="computeroutput"><span class="identifier">adjprec</span></code> will be <code class="computeroutput"><span class="number">5</span></code> (as we need to print <code class="computeroutput"><span class="number">01230</span></code>) 954 </p> 955 <p> 956 The missing preceding zeros in the fractional part have to 957 be supplied by the implementation of this policy function. 958 </p> 959 <p> 960 The return value defines the outcome of the whole generator. 961 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 962 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 963 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 964 output generation continues. 965 </p> 966 </td> 967</tr> 968<tr> 969<td> 970 <p> 971</p> 972<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">CharEncoding</span><span class="special">,</span> 973 <span class="keyword">typename</span> <span class="identifier">Tag</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span> 974<span class="keyword">bool</span> <span class="identifier">exponent</span><span class="special">(</span> 975 <span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="keyword">long</span> <span class="identifier">n</span><span class="special">);</span> 976</pre> 977<p> 978 </p> 979 </td> 980<td> 981 <p> 982 This function is called to generate the exponential part of 983 the number (this is called only if the <code class="computeroutput"><span class="identifier">floatfield</span><span class="special">()</span></code> function returned the <code class="computeroutput"><span class="identifier">fmtflags</span><span class="special">::</span><span class="identifier">scientific</span></code> flag). 984 </p> 985 <p> 986 <code class="computeroutput"><span class="identifier">sink</span></code> is the 987 output iterator to use for generation 988 </p> 989 <p> 990 <code class="computeroutput"><span class="identifier">n</span></code> is the (signed) 991 exponential part of the real number to convert. 992 </p> 993 <p> 994 The template parameters <code class="computeroutput"><span class="identifier">CharEncoding</span></code> 995 and <code class="computeroutput"><span class="identifier">Tag</span></code> are 996 either of the type <code class="computeroutput"><span class="identifier">unused_type</span></code> 997 or describe the character class and conversion to be applied 998 to any output possibly influenced by either the <code class="computeroutput"><span class="identifier">lower</span><span class="special">[]</span></code> 999 or <code class="computeroutput"><span class="identifier">upper</span><span class="special">[]</span></code> 1000 directives. 1001 </p> 1002 <p> 1003 The return value defines the outcome of the whole generator. 1004 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 1005 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 1006 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 1007 output generation continues. 1008 </p> 1009 </td> 1010</tr> 1011<tr> 1012<td> 1013 <p> 1014</p> 1015<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">CharEncoding</span> 1016 <span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Tag</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span> 1017<span class="keyword">bool</span> <span class="identifier">nan</span> <span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span> 1018 <span class="special">,</span> <span class="keyword">bool</span> <span class="identifier">force_sign</span><span class="special">);</span> 1019</pre> 1020<p> 1021 </p> 1022 </td> 1023<td> 1024 <p> 1025 This function is called whenever the number to print is a non-normal 1026 real number of type <code class="computeroutput"><span class="identifier">NaN</span></code>. 1027 </p> 1028 <p> 1029 <code class="computeroutput"><span class="identifier">sink</span></code> is the 1030 output iterator to use for generation 1031 </p> 1032 <p> 1033 <code class="computeroutput"><span class="identifier">n</span></code> is the (signed) 1034 real number to convert 1035 </p> 1036 <p> 1037 <code class="computeroutput"><span class="identifier">force_sign</span></code> 1038 is a flag indicating whether a sign has to be generated even 1039 for non-negative numbers (this is the same as has been returned 1040 from the function <code class="computeroutput"><span class="identifier">force_sign</span><span class="special">()</span></code> described above) 1041 </p> 1042 <p> 1043 The template parameters <code class="computeroutput"><span class="identifier">CharEncoding</span></code> 1044 and <code class="computeroutput"><span class="identifier">Tag</span></code> are 1045 either of the type <code class="computeroutput"><span class="identifier">unused_type</span></code> 1046 or describe the character class and conversion to be applied 1047 to any output possibly influenced by either the <code class="computeroutput"><span class="identifier">lower</span><span class="special">[]</span></code> 1048 or <code class="computeroutput"><span class="identifier">upper</span><span class="special">[]</span></code> 1049 directives. 1050 </p> 1051 <p> 1052 The return value defines the outcome of the whole generator. 1053 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 1054 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 1055 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 1056 output generation continues. 1057 </p> 1058 </td> 1059</tr> 1060<tr> 1061<td> 1062 <p> 1063</p> 1064<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">CharEncoding</span> 1065 <span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Tag</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span> 1066<span class="keyword">bool</span> <span class="identifier">inf</span> <span class="special">(</span><span class="identifier">OutputIterator</span><span class="special">&</span> <span class="identifier">sink</span><span class="special">,</span> <span class="identifier">Num</span> <span class="identifier">n</span> 1067 <span class="special">,</span> <span class="keyword">bool</span> <span class="identifier">force_sign</span><span class="special">);</span> 1068</pre> 1069<p> 1070 </p> 1071 </td> 1072<td> 1073 <p> 1074 This function is called whenever the number to print is a non-normal 1075 real number of type <code class="computeroutput"><span class="identifier">Inf</span></code>. 1076 </p> 1077 <p> 1078 <code class="computeroutput"><span class="identifier">sink</span></code> is the 1079 output iterator to use for generation 1080 </p> 1081 <p> 1082 <code class="computeroutput"><span class="identifier">n</span></code> is the (signed) 1083 real number to convert 1084 </p> 1085 <p> 1086 <code class="computeroutput"><span class="identifier">force_sign</span></code> 1087 is a flag indicating whether a sign has to be generated even 1088 for non-negative numbers (this is the same as has been returned 1089 from the function <code class="computeroutput"><span class="identifier">force_sign</span><span class="special">()</span></code> described above) 1090 </p> 1091 <p> 1092 The template parameters <code class="computeroutput"><span class="identifier">CharEncoding</span></code> 1093 and <code class="computeroutput"><span class="identifier">Tag</span></code> are 1094 either of the type <code class="computeroutput"><span class="identifier">unused_type</span></code> 1095 or describe the character class and conversion to be applied 1096 to any output possibly influenced by either the <code class="computeroutput"><span class="identifier">lower</span><span class="special">[]</span></code> 1097 or <code class="computeroutput"><span class="identifier">upper</span><span class="special">[]</span></code> 1098 directives. 1099 </p> 1100 <p> 1101 The return value defines the outcome of the whole generator. 1102 If it is <code class="computeroutput"><span class="keyword">false</span></code>, 1103 no further output is generated, immediately returning <code class="computeroutput"><span class="keyword">false</span></code> from the calling <code class="computeroutput"><span class="identifier">real_generator</span></code> as well. If 1104 it is <code class="computeroutput"><span class="keyword">true</span></code>, normal 1105 output generation continues. 1106 </p> 1107 </td> 1108</tr> 1109</tbody> 1110</table></div> 1111<div class="tip"><table border="0" summary="Tip"> 1112<tr> 1113<td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../images/tip.png"></td> 1114<th align="left">Tip</th> 1115</tr> 1116<tr><td align="left" valign="top"><p> 1117 The easiest way to implement a proper real number formatting policy 1118 is to derive a new type from the type <code class="computeroutput"><span class="identifier">real_policies</span><span class="special"><></span></code> while overriding the aspects 1119 of the formatting which need to be changed. 1120 </p></td></tr> 1121</table></div> 1122<h6> 1123<a name="spirit.karma.reference.numeric.real_number.h11"></a> 1124 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.complexity"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.complexity">Complexity</a> 1125 </h6> 1126<div class="blockquote"><blockquote class="blockquote"><p> 1127 O(N), where <code class="computeroutput"><span class="identifier">N</span></code> is the 1128 number of digits needed to represent the generated real number. 1129 </p></blockquote></div> 1130<h6> 1131<a name="spirit.karma.reference.numeric.real_number.h12"></a> 1132 <span class="phrase"><a name="spirit.karma.reference.numeric.real_number.example"></a></span><a class="link" href="real_number.html#spirit.karma.reference.numeric.real_number.example">Example</a> 1133 </h6> 1134<div class="note"><table border="0" summary="Note"> 1135<tr> 1136<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> 1137<th align="left">Note</th> 1138</tr> 1139<tr><td align="left" valign="top"><p> 1140 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> 1141 section. 1142 </p></td></tr> 1143</table></div> 1144<p> 1145 Some includes: 1146 </p> 1147<p> 1148</p> 1149<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> 1150<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> 1151<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> 1152<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> 1153<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> 1154<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 1155<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">string</span><span class="special">></span> 1156</pre> 1157<p> 1158 </p> 1159<p> 1160 Some using declarations: 1161 </p> 1162<p> 1163</p> 1164<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> 1165<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">lit</span><span class="special">;</span> 1166</pre> 1167<p> 1168 </p> 1169<p> 1170 Basic usage of an <code class="computeroutput"><span class="identifier">double_</span></code> 1171 generator: 1172 </p> 1173<p> 1174</p> 1175<pre class="programlisting"><span class="identifier">test_generator</span><span class="special">(</span><span class="string">"2.0"</span><span class="special">,</span> <span class="identifier">lit</span><span class="special">(</span><span class="number">2.0</span><span class="special">));</span> 1176<span class="identifier">test_generator</span><span class="special">(</span><span class="string">"2.0"</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">(</span><span class="number">2</span><span class="special">));</span> 1177<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"2.0"</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">(</span><span class="number">2.0</span><span class="special">),</span> <span class="number">2.0</span><span class="special">);</span> 1178<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">""</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">(</span><span class="number">2.0</span><span class="special">),</span> <span class="number">3.0</span><span class="special">);</span> <span class="comment">// fails (as 2.0 != 3.0)!</span> 1179<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"-2.0"</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">,</span> <span class="special">-</span><span class="number">2.0</span><span class="special">);</span> 1180 1181<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"1.234e05"</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">,</span> <span class="number">1234.0e2</span><span class="special">);</span> 1182<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"1.234e-06"</span><span class="special">,</span> <span class="identifier">double_</span><span class="special">,</span> <span class="number">0.000001234</span><span class="special">);</span> 1183</pre> 1184<p> 1185 </p> 1186</div> 1187<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 1188<td align="left"></td> 1189<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p> 1190 Distributed under the Boost Software License, Version 1.0. (See accompanying 1191 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>) 1192 </p> 1193</div></td> 1194</tr></table> 1195<hr> 1196<div class="spirit-nav"> 1197<a accesskey="p" href="signed_int.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../numeric.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="boolean.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 1198</div> 1199</body> 1200</html> 1201
