1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Iterator Concepts</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. Boost.Iterator"> 8<link rel="up" href="../index.html" title="Chapter 1. Boost.Iterator"> 9<link rel="prev" href="../index.html" title="Chapter 1. Boost.Iterator"> 10<link rel="next" href="concepts/traversal.html" title="Traversal"> 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="../index.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="concepts/traversal.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 27<a name="iterator.concepts"></a><a class="link" href="concepts.html" title="Iterator Concepts">Iterator Concepts</a> 28</h2></div></div></div> 29<div class="toc"><dl class="toc"> 30<dt><span class="section"><a href="concepts.html#iterator.concepts.access">Access</a></span></dt> 31<dd><dl> 32<dt><span class="section"><a href="concepts.html#iterator.concepts.access.readable">Readable Iterator 33 Concept</a></span></dt> 34<dt><span class="section"><a href="concepts.html#iterator.concepts.access.writable">Writable Iterator 35 Concept</a></span></dt> 36<dt><span class="section"><a href="concepts.html#iterator.concepts.access.swappable">Swappable Iterator 37 Concept</a></span></dt> 38<dt><span class="section"><a href="concepts.html#iterator.concepts.access.lvalue">Lvalue Iterator Concept</a></span></dt> 39</dl></dd> 40<dt><span class="section"><a href="concepts/traversal.html">Traversal</a></span></dt> 41<dd><dl> 42<dt><span class="section"><a href="concepts/traversal.html#iterator.concepts.traversal.incrementable">Incrementable 43 Iterator Concept</a></span></dt> 44<dt><span class="section"><a href="concepts/traversal.html#iterator.concepts.traversal.single_pass">Single Pass 45 Iterator Concept</a></span></dt> 46<dt><span class="section"><a href="concepts/traversal.html#iterator.concepts.traversal.forward">Forward Traversal 47 Concept</a></span></dt> 48<dt><span class="section"><a href="concepts/traversal.html#iterator.concepts.traversal.bidirectional">Bidirectional 49 Traversal Concept</a></span></dt> 50<dt><span class="section"><a href="concepts/traversal.html#iterator.concepts.traversal.random_access">Random Access 51 Traversal Concept</a></span></dt> 52</dl></dd> 53</dl></div> 54<div class="section"> 55<div class="titlepage"><div><div><h3 class="title"> 56<a name="iterator.concepts.access"></a><a class="link" href="concepts.html#iterator.concepts.access" title="Access">Access</a> 57</h3></div></div></div> 58<div class="toc"><dl class="toc"> 59<dt><span class="section"><a href="concepts.html#iterator.concepts.access.readable">Readable Iterator 60 Concept</a></span></dt> 61<dt><span class="section"><a href="concepts.html#iterator.concepts.access.writable">Writable Iterator 62 Concept</a></span></dt> 63<dt><span class="section"><a href="concepts.html#iterator.concepts.access.swappable">Swappable Iterator 64 Concept</a></span></dt> 65<dt><span class="section"><a href="concepts.html#iterator.concepts.access.lvalue">Lvalue Iterator Concept</a></span></dt> 66</dl></div> 67<div class="section"> 68<div class="titlepage"><div><div><h4 class="title"> 69<a name="iterator.concepts.access.readable"></a><a class="link" href="concepts.html#iterator.concepts.access.readable" title="Readable Iterator Concept">Readable Iterator 70 Concept</a> 71</h4></div></div></div> 72<p> 73 A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code> 74 models the <span class="bold"><strong>Readable Iterator</strong></span> concept for 75 value type <code class="computeroutput"><span class="identifier">T</span></code> if, in addition 76 to <code class="computeroutput"><span class="identifier">X</span></code> being Assignable and 77 Copy Constructible, the following expressions are valid and respect the 78 stated semantics. <code class="computeroutput"><span class="identifier">U</span></code> is 79 the type of any specified member of type <code class="computeroutput"><span class="identifier">T</span></code>. 80 </p> 81<div class="table"> 82<a name="iterator.concepts.access.readable.readable_iterator_requirements_i"></a><p class="title"><b>Table 1.1. Readable Iterator Requirements (in addition to Assignable and Copy 83 Constructible)</b></p> 84<div class="table-contents"><table class="table" summary="Readable Iterator Requirements (in addition to Assignable and Copy 85 Constructible)"> 86<colgroup> 87<col> 88<col> 89<col> 90</colgroup> 91<thead><tr> 92<th> 93 <p> 94 Expression 95 </p> 96 </th> 97<th> 98 <p> 99 Return Type 100 </p> 101 </th> 102<th> 103 <p> 104 Note/Precondition 105 </p> 106 </th> 107</tr></thead> 108<tbody> 109<tr> 110<td> 111 <p> 112 <code class="computeroutput"><span class="identifier">iterator_traits</span><span class="special"><</span><span class="identifier">X</span><span class="special">>::</span><span class="identifier">value_type</span></code> 113 </p> 114 </td> 115<td> 116 <p> 117 <code class="computeroutput"><span class="identifier">T</span></code> 118 </p> 119 </td> 120<td> 121 <p> 122 Any non-reference, non cv-qualified type 123 </p> 124 </td> 125</tr> 126<tr> 127<td> 128 <p> 129 <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code> 130 </p> 131 </td> 132<td> 133 <p> 134 Convertible to <code class="computeroutput"><span class="identifier">T</span></code> 135 </p> 136 </td> 137<td> 138 <p> 139 pre: <code class="computeroutput"><span class="identifier">a</span></code> is dereferenceable. 140 If <code class="computeroutput"><span class="identifier">a</span> <span class="special">==</span> 141 <span class="identifier">b</span></code> then <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code> 142 is equivalent to <code class="computeroutput"><span class="special">*</span><span class="identifier">b</span></code>. 143 </p> 144 </td> 145</tr> 146<tr> 147<td> 148 <p> 149 <code class="computeroutput"><span class="identifier">a</span><span class="special">-></span><span class="identifier">m</span></code> 150 </p> 151 </td> 152<td> 153 <p> 154 <code class="computeroutput"><span class="identifier">U</span><span class="special">&</span></code> 155 </p> 156 </td> 157<td> 158 <p> 159 pre: <code class="computeroutput"><span class="special">(*</span><span class="identifier">a</span><span class="special">).</span><span class="identifier">m</span></code> 160 is well-defined. Equivalent to <code class="computeroutput"><span class="special">(*</span><span class="identifier">a</span><span class="special">).</span><span class="identifier">m</span></code>. 161 </p> 162 </td> 163</tr> 164</tbody> 165</table></div> 166</div> 167<br class="table-break"> 168</div> 169<div class="section"> 170<div class="titlepage"><div><div><h4 class="title"> 171<a name="iterator.concepts.access.writable"></a><a class="link" href="concepts.html#iterator.concepts.access.writable" title="Writable Iterator Concept">Writable Iterator 172 Concept</a> 173</h4></div></div></div> 174<p> 175 A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code> 176 models the <span class="bold"><strong>Writable Iterator</strong></span> concept if, 177 in addition to <code class="computeroutput"><span class="identifier">X</span></code> being 178 Copy Constructible, the following expressions are valid and respect the 179 stated semantics. Writable Iterators have an associated <span class="bold"><strong>set 180 of value types</strong></span>. 181 </p> 182<div class="table"> 183<a name="iterator.concepts.access.writable.writable_iterator_requirements_i"></a><p class="title"><b>Table 1.2. Writable Iterator Requirements (in addition to Copy Constructible)</b></p> 184<div class="table-contents"><table class="table" summary="Writable Iterator Requirements (in addition to Copy Constructible)"> 185<colgroup> 186<col> 187<col> 188<col> 189</colgroup> 190<thead><tr> 191<th> 192 <p> 193 Expression 194 </p> 195 </th> 196<th> 197 <p> 198 Return Type 199 </p> 200 </th> 201<th> 202 <p> 203 Precondition 204 </p> 205 </th> 206</tr></thead> 207<tbody><tr> 208<td> 209 <p> 210 <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span> 211 <span class="special">=</span> <span class="identifier">o</span></code> 212 </p> 213 </td> 214<td> 215 </td> 216<td> 217 <p> 218 pre: The type of <code class="computeroutput"><span class="identifier">o</span></code> 219 is in the set of value types of <code class="computeroutput"><span class="identifier">X</span></code> 220 </p> 221 </td> 222</tr></tbody> 223</table></div> 224</div> 225<br class="table-break"> 226</div> 227<div class="section"> 228<div class="titlepage"><div><div><h4 class="title"> 229<a name="iterator.concepts.access.swappable"></a><a class="link" href="concepts.html#iterator.concepts.access.swappable" title="Swappable Iterator Concept">Swappable Iterator 230 Concept</a> 231</h4></div></div></div> 232<p> 233 A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code> 234 models the <span class="bold"><strong>Swappable Iterator</strong></span> concept 235 if, in addition to <code class="computeroutput"><span class="identifier">X</span></code> being 236 Copy Constructible, the following expressions are valid and respect the 237 stated semantics. 238 </p> 239<div class="table"> 240<a name="iterator.concepts.access.swappable.swappable_iterator_requirements_"></a><p class="title"><b>Table 1.3. Swappable Iterator Requirements (in addition to Copy Constructible)</b></p> 241<div class="table-contents"><table class="table" summary="Swappable Iterator Requirements (in addition to Copy Constructible)"> 242<colgroup> 243<col> 244<col> 245<col> 246</colgroup> 247<thead><tr> 248<th> 249 <p> 250 Expression 251 </p> 252 </th> 253<th> 254 <p> 255 Return Type 256 </p> 257 </th> 258<th> 259 <p> 260 Postcondition 261 </p> 262 </th> 263</tr></thead> 264<tbody><tr> 265<td> 266 <p> 267 <code class="computeroutput"><span class="identifier">iter_swap</span><span class="special">(</span><span class="identifier">a</span><span class="special">,</span> 268 <span class="identifier">b</span><span class="special">)</span></code> 269 </p> 270 </td> 271<td> 272 <p> 273 <code class="computeroutput"><span class="keyword">void</span></code> 274 </p> 275 </td> 276<td> 277 <p> 278 the pointed to values are exchanged 279 </p> 280 </td> 281</tr></tbody> 282</table></div> 283</div> 284<br class="table-break"><div class="blurb"> 285<div class="titlepage"><div><div><p class="title"><b></b></p></div></div></div> 286<p> 287 <span class="bold"><strong>Note:</strong></span> An iterator that is a model of the 288 <span class="bold"><strong>Readable</strong></span> and <span class="bold"><strong>Writable 289 Iterator</strong></span> concepts is also a model of <span class="bold"><strong>Swappable 290 Iterator</strong></span>. <span class="bold"><strong>--end note</strong></span> 291 </p> 292</div> 293</div> 294<div class="section"> 295<div class="titlepage"><div><div><h4 class="title"> 296<a name="iterator.concepts.access.lvalue"></a><a class="link" href="concepts.html#iterator.concepts.access.lvalue" title="Lvalue Iterator Concept">Lvalue Iterator Concept</a> 297</h4></div></div></div> 298<p> 299 The <span class="bold"><strong>Lvalue Iterator</strong></span> concept adds the requirement 300 that the return type of <code class="computeroutput"><span class="keyword">operator</span><span class="special">*</span></code> type be a reference to the value type 301 of the iterator. 302 </p> 303<div class="table"> 304<a name="iterator.concepts.access.lvalue.lvalue_iterator_requirements"></a><p class="title"><b>Table 1.4. Lvalue Iterator Requirements</b></p> 305<div class="table-contents"><table class="table" summary="Lvalue Iterator Requirements"> 306<colgroup> 307<col> 308<col> 309<col> 310</colgroup> 311<thead><tr> 312<th> 313 <p> 314 Expression 315 </p> 316 </th> 317<th> 318 <p> 319 Return Type 320 </p> 321 </th> 322<th> 323 <p> 324 Note/Assertion 325 </p> 326 </th> 327</tr></thead> 328<tbody><tr> 329<td> 330 <p> 331 <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code> 332 </p> 333 </td> 334<td> 335 <p> 336 <code class="computeroutput"><span class="identifier">T</span><span class="special">&</span></code> 337 </p> 338 </td> 339<td> 340 <p> 341 <code class="computeroutput"><span class="identifier">T</span></code> is <span class="bold"><strong>cv</strong></span> <code class="computeroutput"><span class="identifier">iterator_traits</span><span class="special"><</span><span class="identifier">X</span><span class="special">>::</span><span class="identifier">value_type</span></code> 342 where <span class="bold"><strong>cv</strong></span> is an optional cv-qualification. 343 pre: <code class="computeroutput"><span class="identifier">a</span></code> is dereferenceable. 344 If <code class="computeroutput"><span class="identifier">a</span> <span class="special">==</span> 345 <span class="identifier">b</span></code> then <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code> 346 is equivalent to <code class="computeroutput"><span class="special">*</span><span class="identifier">b</span></code>. 347 </p> 348 </td> 349</tr></tbody> 350</table></div> 351</div> 352<br class="table-break"> 353</div> 354</div> 355</div> 356<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 357<td align="left"></td> 358<td align="right"><div class="copyright-footer">Copyright © 2003, 2005 David Abrahams Jeremy Siek Thomas 359 Witt<p> 360 Distributed under the Boost Software License, Version 1.0. (See accompanying 361 file LICENSE_1_0.txt or copy at <ulink url="http://www.boost.org/LICENSE_1_0.txt"> 362 http://www.boost.org/LICENSE_1_0.txt </ulink>) 363 </p> 364</div></td> 365</tr></table> 366<hr> 367<div class="spirit-nav"> 368<a accesskey="p" href="../index.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="concepts/traversal.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 369</div> 370</body> 371</html> 372
