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  25 <div class="section">
  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="range.reference.concept_implementation.semantics.functions"></a><a class="link" href="functions.html" title="Functions">Functions</a>
  28 </h5></div></div></div>
  29 <div class="informaltable"><table class="table">
  30 <colgroup>
  31 <col>
  32 <col>
  33 <col>
  34 </colgroup>
  35 <thead><tr>
  36 <th>
  37                     <p>
  38                       Expression
  39                     </p>
  40                   </th>
  41 <th>
  42                     <p>
  43                       Return type
  44                     </p>
  45                   </th>
  46 <th>
  47                     <p>
  48                       Returns
  49                     </p>
  50                   </th>
  51 <th>
  52                     <p>
  53                       Complexity
  54                     </p>
  55                   </th>
  56 </tr></thead>
  57 <tbody>
  58 <tr>
  59 <td>
  60                     <p>
  61                       <code class="computeroutput"><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
  62                     </p>
  63                   </td>
  64 <td>
  65                     <p>
  66                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
  67                     </p>
  68                   </td>
  69 <td>
  70                     <p>
  71                       <code class="computeroutput"><span class="identifier">p</span><span class="special">.</span><span class="identifier">first</span></code> if <code class="computeroutput"><span class="identifier">p</span></code>
  72                       is of type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> <code class="computeroutput"><span class="identifier">a</span></code>
  73                       if <code class="computeroutput"><span class="identifier">a</span></code> is an
  74                       array <code class="computeroutput"><span class="identifier">range_begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code> if that expression would invoke
  75                       a function found by ADL <code class="computeroutput"><span class="identifier">t</span><span class="special">.</span><span class="identifier">begin</span><span class="special">()</span></code> otherwise
  76                     </p>
  77                   </td>
  78 <td>
  79                     <p>
  80                       constant time
  81                     </p>
  82                   </td>
  83 </tr>
  84 <tr>
  85 <td>
  86                     <p>
  87                       <code class="computeroutput"><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
  88                     </p>
  89                   </td>
  90 <td>
  91                     <p>
  92                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
  93                     </p>
  94                   </td>
  95 <td>
  96                     <p>
  97                       <code class="computeroutput"><span class="identifier">p</span><span class="special">.</span><span class="identifier">second</span></code> if <code class="computeroutput"><span class="identifier">p</span></code>
  98                       is of type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> <code class="computeroutput"><span class="identifier">a</span>
  99                       <span class="special">+</span> <span class="identifier">sz</span></code>
 100                       if <code class="computeroutput"><span class="identifier">a</span></code> is an
 101                       array of size <code class="computeroutput"><span class="identifier">sz</span></code>
 102                       <code class="computeroutput"><span class="identifier">range_end</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 103                       if that expression would invoke a function found by ADL <code class="computeroutput"><span class="identifier">t</span><span class="special">.</span><span class="identifier">end</span><span class="special">()</span></code>
 104                       otherwise
 105                     </p>
 106                   </td>
 107 <td>
 108                     <p>
 109                       constant time
 110                     </p>
 111                   </td>
 112 </tr>
 113 <tr>
 114 <td>
 115                     <p>
 116                       <code class="computeroutput"><span class="identifier">empty</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 117                     </p>
 118                   </td>
 119 <td>
 120                     <p>
 121                       <code class="computeroutput"><span class="keyword">bool</span></code>
 122                     </p>
 123                   </td>
 124 <td>
 125                     <p>
 126                       <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span>
 127                       <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 128                     </p>
 129                   </td>
 130 <td>
 131                     <p>
 132                       constant time
 133                     </p>
 134                   </td>
 135 </tr>
 136 <tr>
 137 <td>
 138                     <p>
 139                       <code class="computeroutput"><span class="identifier">distance</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 140                     </p>
 141                   </td>
 142 <td>
 143                     <p>
 144                       <code class="computeroutput"><span class="identifier">range_difference</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 145                     </p>
 146                   </td>
 147 <td>
 148                     <p>
 149                       <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">distance</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">),</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 150                     </p>
 151                   </td>
 152 <td>
 153                     <p>
 154                       -
 155                     </p>
 156                   </td>
 157 </tr>
 158 <tr>
 159 <td>
 160                     <p>
 161                       <code class="computeroutput"><span class="identifier">size</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 162                     </p>
 163                   </td>
 164 <td>
 165                     <p>
 166                       <code class="computeroutput"><span class="identifier">range_size</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 167                     </p>
 168                   </td>
 169 <td>
 170                     <p>
 171                       <code class="computeroutput"><span class="identifier">range_calculate_size</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code> which by default is <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span>
 172                       <span class="special">-</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>. Users may supply alternative
 173                       implementations by implementing <code class="computeroutput"><span class="identifier">range_calculate_size</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code> so that it will be found via
 174                       ADL
 175                     </p>
 176                   </td>
 177 <td>
 178                     <p>
 179                       constant time
 180                     </p>
 181                   </td>
 182 </tr>
 183 <tr>
 184 <td>
 185                     <p>
 186                       <code class="computeroutput"><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 187                     </p>
 188                   </td>
 189 <td>
 190                     <p>
 191                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 192                     </p>
 193                   </td>
 194 <td>
 195                     <p>
 196                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 197                     </p>
 198                   </td>
 199 <td>
 200                     <p>
 201                       constant time
 202                     </p>
 203                   </td>
 204 </tr>
 205 <tr>
 206 <td>
 207                     <p>
 208                       <code class="computeroutput"><span class="identifier">rend</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 209                     </p>
 210                   </td>
 211 <td>
 212                     <p>
 213                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 214                     </p>
 215                   </td>
 216 <td>
 217                     <p>
 218                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 219                     </p>
 220                   </td>
 221 <td>
 222                     <p>
 223                       constant time
 224                     </p>
 225                   </td>
 226 </tr>
 227 <tr>
 228 <td>
 229                     <p>
 230                       <code class="computeroutput"><span class="identifier">const_begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 231                     </p>
 232                   </td>
 233 <td>
 234                     <p>
 235                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 236                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 237                     </p>
 238                   </td>
 239 <td>
 240                     <p>
 241                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 242                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 243                     </p>
 244                   </td>
 245 <td>
 246                     <p>
 247                       constant time
 248                     </p>
 249                   </td>
 250 </tr>
 251 <tr>
 252 <td>
 253                     <p>
 254                       <code class="computeroutput"><span class="identifier">const_end</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 255                     </p>
 256                   </td>
 257 <td>
 258                     <p>
 259                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 260                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 261                     </p>
 262                   </td>
 263 <td>
 264                     <p>
 265                       <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 266                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 267                     </p>
 268                   </td>
 269 <td>
 270                     <p>
 271                       constant time
 272                     </p>
 273                   </td>
 274 </tr>
 275 <tr>
 276 <td>
 277                     <p>
 278                       <code class="computeroutput"><span class="identifier">const_rbegin</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 279                     </p>
 280                   </td>
 281 <td>
 282                     <p>
 283                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 284                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 285                     </p>
 286                   </td>
 287 <td>
 288                     <p>
 289                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 290                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 291                     </p>
 292                   </td>
 293 <td>
 294                     <p>
 295                       constant time
 296                     </p>
 297                   </td>
 298 </tr>
 299 <tr>
 300 <td>
 301                     <p>
 302                       <code class="computeroutput"><span class="identifier">const_rend</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 303                     </p>
 304                   </td>
 305 <td>
 306                     <p>
 307                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 308                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 309                     </p>
 310                   </td>
 311 <td>
 312                     <p>
 313                       <code class="computeroutput"><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
 314                       <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 315                     </p>
 316                   </td>
 317 <td>
 318                     <p>
 319                       constant time
 320                     </p>
 321                   </td>
 322 </tr>
 323 <tr>
 324 <td>
 325                     <p>
 326                       <code class="computeroutput"><span class="identifier">as_literal</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 327                     </p>
 328                   </td>
 329 <td>
 330                     <p>
 331                       <code class="computeroutput"><span class="identifier">iterator_range</span><span class="special">&lt;</span><span class="identifier">U</span><span class="special">&gt;</span></code> where <code class="computeroutput"><span class="identifier">U</span></code>
 332                       is <code class="computeroutput"><span class="identifier">Char</span><span class="special">*</span></code>
 333                       if <code class="computeroutput"><span class="identifier">x</span></code> is a pointer
 334                       to a string and <code class="computeroutput"><span class="identifier">U</span></code>
 335                       is <code class="computeroutput"><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
 336                       otherwise
 337                     </p>
 338                   </td>
 339 <td>
 340                     <p>
 341                       <code class="computeroutput"><span class="special">[</span><span class="identifier">s</span><span class="special">,</span><span class="identifier">s</span>
 342                       <span class="special">+</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">char_traits</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">length</span><span class="special">(</span><span class="identifier">s</span><span class="special">))</span></code> if <code class="computeroutput"><span class="identifier">s</span></code>
 343                       is a <code class="computeroutput"><span class="identifier">Char</span><span class="special">*</span></code>
 344                       or an array of <code class="computeroutput"><span class="identifier">Char</span></code>
 345                       <code class="computeroutput"><span class="special">[</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">),</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code> otherwise
 346                     </p>
 347                   </td>
 348 <td>
 349                     <p>
 350                       linear time for pointers to a string or arrays of <code class="computeroutput"><span class="identifier">Char</span></code>, constant time otherwise
 351                     </p>
 352                   </td>
 353 </tr>
 354 <tr>
 355 <td>
 356                     <p>
 357                       <code class="computeroutput"><span class="identifier">as_array</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code>
 358                     </p>
 359                   </td>
 360 <td>
 361                     <p>
 362                       <code class="computeroutput"><span class="identifier">iterator_range</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;</span></code>
 363                     </p>
 364                   </td>
 365 <td>
 366                     <p>
 367                       <code class="computeroutput"><span class="special">[</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">x</span><span class="special">),</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">x</span><span class="special">))</span></code>
 368                     </p>
 369                   </td>
 370 </tr>
 371 </tbody>
 372 </table></div>
 373 <p>
 374             The special <code class="computeroutput"><span class="identifier">const_</span></code>-named
 375             functions are useful when you want to document clearly that your code
 376             is read-only.
 377           </p>
 378 <p>
 379             <code class="computeroutput"><span class="identifier">as_literal</span><span class="special">()</span></code>
 380             can be used <span class="emphasis"><em><span class="bold"><strong>internally</strong></span></em></span>
 381             in string algorithm libraries such that arrays of characters are handled
 382             correctly.
 383           </p>
 384 <p>
 385             <code class="computeroutput"><span class="identifier">as_array</span><span class="special">()</span></code>
 386             can be used with string algorithm libraries to make it clear that arrays
 387             of characters are handled like an array and not like a string.
 388           </p>
 389 <p>
 390             Notice that the above functions should always be called with qualification
 391             (<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span></code>)
 392             to prevent <span class="emphasis"><em><span class="bold"><strong>unintended</strong></span></em></span>
 393             Argument Dependent Lookup (ADL).
 394           </p>
 395 </div>
 396 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 397 <td align="left"></td>
 398 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2010 Thorsten Ottosen,
 399       Neil Groves<p>
 400         Distributed under the Boost Software License, Version 1.0. (See accompanying
 401         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>)
 402       </p>
 403 </div></td>
 404 </tr></table>
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