1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Iterator Facade</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="Chapter 1. Fusion 2.2"> 8<link rel="up" href="../extension.html" title="Extension"> 9<link rel="prev" href="sequence_facade.html" title="Sequence Facade"> 10<link rel="next" href="../functional.html" title="Functional"> 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="sequence_facade.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../extension.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="../functional.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="fusion.extension.iterator_facade"></a><a class="link" href="iterator_facade.html" title="Iterator Facade">Iterator Facade</a> 28</h3></div></div></div> 29<h5> 30<a name="fusion.extension.iterator_facade.h0"></a> 31 <span class="phrase"><a name="fusion.extension.iterator_facade.description"></a></span><a class="link" href="iterator_facade.html#fusion.extension.iterator_facade.description">Description</a> 32 </h5> 33<p> 34 The <a class="link" href="iterator_facade.html" title="Iterator Facade"><code class="computeroutput"><span class="identifier">iterator_facade</span></code></a> 35 template provides an intrusive mechanism for producing a conforming Fusion 36 iterator. 37 </p> 38<h5> 39<a name="fusion.extension.iterator_facade.h1"></a> 40 <span class="phrase"><a name="fusion.extension.iterator_facade.synopsis"></a></span><a class="link" href="iterator_facade.html#fusion.extension.iterator_facade.synopsis">Synopsis</a> 41 </h5> 42<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Derived</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">TravesalTag</span><span class="special">></span> 43<span class="keyword">struct</span> <span class="identifier">iterator_facade</span><span class="special">;</span> 44</pre> 45<h5> 46<a name="fusion.extension.iterator_facade.h2"></a> 47 <span class="phrase"><a name="fusion.extension.iterator_facade.usage"></a></span><a class="link" href="iterator_facade.html#fusion.extension.iterator_facade.usage">Usage</a> 48 </h5> 49<p> 50 The user of iterator_facade derives his iterator type from a specialization 51 of iterator_facade and passes the derived iterator type as the first template 52 parameter. The second template parameter should be the traversal category 53 of the iterator being implemented. 54 </p> 55<p> 56 The user must implement the key expressions required by their iterator type. 57 </p> 58<div class="table"> 59<a name="fusion.extension.iterator_facade.t0"></a><p class="title"><b>Table 1.108. Parameters</b></p> 60<div class="table-contents"><table class="table" summary="Parameters"> 61<colgroup> 62<col> 63<col> 64</colgroup> 65<thead><tr> 66<th> 67 <p> 68 Name 69 </p> 70 </th> 71<th> 72 <p> 73 Description 74 </p> 75 </th> 76</tr></thead> 77<tbody> 78<tr> 79<td> 80 <p> 81 <code class="computeroutput"><span class="identifier">iterator</span></code>, <code class="computeroutput"><span class="identifier">It</span></code>, <code class="computeroutput"><span class="identifier">It1</span></code>, 82 <code class="computeroutput"><span class="identifier">It2</span></code> 83 </p> 84 </td> 85<td> 86 <p> 87 A type derived from <a class="link" href="iterator_facade.html" title="Iterator Facade"><code class="computeroutput"><span class="identifier">iterator_facade</span></code></a> 88 </p> 89 </td> 90</tr> 91<tr> 92<td> 93 <p> 94 <code class="computeroutput"><span class="identifier">N</span></code> 95 </p> 96 </td> 97<td> 98 <p> 99 An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL 100 Integral Constant</a> 101 </p> 102 </td> 103</tr> 104</tbody> 105</table></div> 106</div> 107<br class="table-break"><div class="table"> 108<a name="fusion.extension.iterator_facade.t1"></a><p class="title"><b>Table 1.109. Key Expressions</b></p> 109<div class="table-contents"><table class="table" summary="Key Expressions"> 110<colgroup> 111<col> 112<col> 113<col> 114</colgroup> 115<thead><tr> 116<th> 117 <p> 118 Expression 119 </p> 120 </th> 121<th> 122 <p> 123 Result 124 </p> 125 </th> 126<th> 127 <p> 128 Default 129 </p> 130 </th> 131</tr></thead> 132<tbody> 133<tr> 134<td> 135 <p> 136 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">value_of</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 137 </p> 138 </td> 139<td> 140 <p> 141 The element stored at iterator position <code class="computeroutput"><span class="identifier">It</span></code> 142 </p> 143 </td> 144<td> 145 <p> 146 None 147 </p> 148 </td> 149</tr> 150<tr> 151<td> 152 <p> 153 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 154 </p> 155 </td> 156<td> 157 <p> 158 The type returned when dereferencing an iterator of type <code class="computeroutput"><span class="identifier">It</span></code> 159 </p> 160 </td> 161<td> 162 <p> 163 None 164 </p> 165 </td> 166</tr> 167<tr> 168<td> 169 <p> 170 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></code> 171 </p> 172 </td> 173<td> 174 <p> 175 Dereferences iterator <code class="computeroutput"><span class="identifier">it</span></code> 176 </p> 177 </td> 178<td> 179 <p> 180 None 181 </p> 182 </td> 183</tr> 184<tr> 185<td> 186 <p> 187 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">next</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 188 </p> 189 </td> 190<td> 191 <p> 192 The type of the next element from <code class="computeroutput"><span class="identifier">It</span></code> 193 </p> 194 </td> 195<td> 196 <p> 197 None 198 </p> 199 </td> 200</tr> 201<tr> 202<td> 203 <p> 204 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">next</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></code> 205 </p> 206 </td> 207<td> 208 <p> 209 The next iterator after <code class="computeroutput"><span class="identifier">it</span></code> 210 </p> 211 </td> 212<td> 213 <p> 214 None 215 </p> 216 </td> 217</tr> 218<tr> 219<td> 220 <p> 221 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">prior</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 222 </p> 223 </td> 224<td> 225 <p> 226 The type of the next element from <code class="computeroutput"><span class="identifier">It</span></code> 227 </p> 228 </td> 229<td> 230 <p> 231 None 232 </p> 233 </td> 234</tr> 235<tr> 236<td> 237 <p> 238 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">prior</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></code> 239 </p> 240 </td> 241<td> 242 <p> 243 The next iterator after <code class="computeroutput"><span class="identifier">it</span></code> 244 </p> 245 </td> 246<td> 247 <p> 248 None 249 </p> 250 </td> 251</tr> 252<tr> 253<td> 254 <p> 255 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">advance</span><span class="special"><</span><span class="identifier">It</span><span class="special">,</span> <span class="identifier">N</span><span class="special">>::</span><span class="identifier">type</span></code> 256 </p> 257 </td> 258<td> 259 <p> 260 The type of an iterator advanced <code class="computeroutput"><span class="identifier">N</span></code> 261 elements from <code class="computeroutput"><span class="identifier">It</span></code> 262 </p> 263 </td> 264<td> 265 <p> 266 Implemented in terms of <code class="computeroutput"><span class="identifier">next</span></code> 267 and <code class="computeroutput"><span class="identifier">prior</span></code> 268 </p> 269 </td> 270</tr> 271<tr> 272<td> 273 <p> 274 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">advance</span><span class="special"><</span><span class="identifier">It</span><span class="special">,</span> <span class="identifier">N</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></code> 275 </p> 276 </td> 277<td> 278 <p> 279 An iterator advanced <code class="computeroutput"><span class="identifier">N</span></code> 280 elements from <code class="computeroutput"><span class="identifier">it</span></code> 281 </p> 282 </td> 283<td> 284 <p> 285 Implemented in terms of <code class="computeroutput"><span class="identifier">next</span></code> 286 and <code class="computeroutput"><span class="identifier">prior</span></code> 287 </p> 288 </td> 289</tr> 290<tr> 291<td> 292 <p> 293 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">distance</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">type</span></code> 294 </p> 295 </td> 296<td> 297 <p> 298 The distance between iterators of type <code class="computeroutput"><span class="identifier">It1</span></code> 299 and <code class="computeroutput"><span class="identifier">It2</span></code> as an 300 <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL 301 Integral Constant</a> 302 </p> 303 </td> 304<td> 305 <p> 306 None 307 </p> 308 </td> 309</tr> 310<tr> 311<td> 312 <p> 313 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">distance</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it1</span><span class="special">,</span> <span class="identifier">it2</span><span class="special">)</span></code> 314 </p> 315 </td> 316<td> 317 <p> 318 The distance between iterator <code class="computeroutput"><span class="identifier">it1</span></code> 319 and <code class="computeroutput"><span class="identifier">it2</span></code> 320 </p> 321 </td> 322<td> 323 <p> 324 None 325 </p> 326 </td> 327</tr> 328<tr> 329<td> 330 <p> 331 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">equal_to</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">type</span></code> 332 </p> 333 </td> 334<td> 335 <p> 336 Returns <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code> if <code class="computeroutput"><span class="identifier">It1</span></code> 337 is equal to <code class="computeroutput"><span class="identifier">It2</span></code>, 338 <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code> otherwise. 339 </p> 340 </td> 341<td> 342 <p> 343 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">same_type</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> 344 <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">type</span></code> 345 </p> 346 </td> 347</tr> 348<tr> 349<td> 350 <p> 351 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">equal_to</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it1</span><span class="special">,</span> <span class="identifier">it2</span><span class="special">)</span></code> 352 </p> 353 </td> 354<td> 355 <p> 356 Returns a type convertible to <code class="computeroutput"><span class="keyword">bool</span></code> 357 that evaluates to <code class="computeroutput"><span class="keyword">true</span></code> 358 if <code class="computeroutput"><span class="identifier">It1</span></code> is equal 359 to <code class="computeroutput"><span class="identifier">It2</span></code>, <code class="computeroutput"><span class="keyword">false</span></code> otherwise. 360 </p> 361 </td> 362<td> 363 <p> 364 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">same_type</span><span class="special"><</span><span class="identifier">It1</span><span class="special">,</span> 365 <span class="identifier">It2</span><span class="special">>::</span><span class="identifier">type</span><span class="special">()</span></code> 366 </p> 367 </td> 368</tr> 369<tr> 370<td> 371 <p> 372 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">key_of</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 373 </p> 374 </td> 375<td> 376 <p> 377 The key type associated with the element from <code class="computeroutput"><span class="identifier">It</span></code> 378 </p> 379 </td> 380<td> 381 <p> 382 None 383 </p> 384 </td> 385</tr> 386<tr> 387<td> 388 <p> 389 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">value_of_data</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 390 </p> 391 </td> 392<td> 393 <p> 394 The type of the data property associated with the element from 395 <code class="computeroutput"><span class="identifier">It</span></code> 396 </p> 397 </td> 398<td> 399 <p> 400 None 401 </p> 402 </td> 403</tr> 404<tr> 405<td> 406 <p> 407 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref_data</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">type</span></code> 408 </p> 409 </td> 410<td> 411 <p> 412 The type that will be returned by dereferencing the data property 413 of the element from <code class="computeroutput"><span class="identifier">It</span></code> 414 </p> 415 </td> 416<td> 417 <p> 418 None 419 </p> 420 </td> 421</tr> 422<tr> 423<td> 424 <p> 425 <code class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref_data</span><span class="special"><</span><span class="identifier">It</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></code> 426 </p> 427 </td> 428<td> 429 <p> 430 Deferences the data property associated with the element referenced 431 by <code class="computeroutput"><span class="identifier">it</span></code> 432 </p> 433 </td> 434<td> 435 <p> 436 None 437 </p> 438 </td> 439</tr> 440</tbody> 441</table></div> 442</div> 443<br class="table-break"><h5> 444<a name="fusion.extension.iterator_facade.h3"></a> 445 <span class="phrase"><a name="fusion.extension.iterator_facade.header"></a></span><a class="link" href="iterator_facade.html#fusion.extension.iterator_facade.header">Header</a> 446 </h5> 447<pre class="programlisting"><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">iterator</span><span class="special">/</span><span class="identifier">iterator_facade</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 448<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">iterator_facade</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 449</pre> 450<h5> 451<a name="fusion.extension.iterator_facade.h4"></a> 452 <span class="phrase"><a name="fusion.extension.iterator_facade.example"></a></span><a class="link" href="iterator_facade.html#fusion.extension.iterator_facade.example">Example</a> 453 </h5> 454<p> 455 A full working example using <a class="link" href="iterator_facade.html" title="Iterator Facade"><code class="computeroutput"><span class="identifier">iterator_facade</span></code></a> is provided in triple.cpp 456 in the extension examples. 457 </p> 458</div> 459<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 460<td align="left"></td> 461<td align="right"><div class="copyright-footer">Copyright © 2001-2006, 2011, 2012 Joel de Guzman, 462 Dan Marsden, Tobias Schwinger<p> 463 Distributed under the Boost Software License, Version 1.0. (See accompanying 464 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>) 465 </p> 466</div></td> 467</tr></table> 468<hr> 469<div class="spirit-nav"> 470<a accesskey="p" href="sequence_facade.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../extension.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="../functional.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 471</div> 472</body> 473</html> 474
