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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_regex.ref.syntax_option_type.syntax_option_type_extended"></a><a class="link" href="syntax_option_type_extended.html" title="Options for POSIX Extended Regular Expressions">Options
  28         for POSIX Extended Regular Expressions</a>
  29 </h4></div></div></div>
  30 <p>
  31           Exactly one of the following must always be set for <a class="link" href="../../syntax/basic_extended.html" title="POSIX Extended Regular Expression Syntax">POSIX
  32           extended regular expressions</a>:
  33         </p>
  34 <div class="informaltable"><table class="table">
  35 <colgroup>
  36 <col>
  37 <col>
  38 <col>
  39 </colgroup>
  40 <thead><tr>
  41 <th>
  42                   <p>
  43                     Element
  44                   </p>
  45                 </th>
  46 <th>
  47                   <p>
  48                     Standardized
  49                   </p>
  50                 </th>
  51 <th>
  52                   <p>
  53                     Effect when set
  54                   </p>
  55                 </th>
  56 </tr></thead>
  57 <tbody>
  58 <tr>
  59 <td>
  60                   <p>
  61                     extended
  62                   </p>
  63                 </td>
  64 <td>
  65                   <p>
  66                     Yes
  67                   </p>
  68                 </td>
  69 <td>
  70                   <p>
  71                     Specifies that the grammar recognized by the regular expression
  72                     engine is the same as that used by POSIX extended regular expressions
  73                     in IEEE Std 1003.1-2001, Portable Operating System Interface
  74                     (POSIX ), Base Definitions and Headers, Section 9, Regular Expressions
  75                     (FWD.1).
  76                   </p>
  77                   <p>
  78                     Refer to the <a class="link" href="../../syntax/basic_extended.html" title="POSIX Extended Regular Expression Syntax">POSIX
  79                     extended regular expression guide</a> for more information.
  80                   </p>
  81                   <p>
  82                     In addition some perl-style escape sequences are supported (The
  83                     POSIX standard specifies that only "special" characters
  84                     may be escaped, all other escape sequences result in undefined
  85                     behavior).
  86                   </p>
  87                 </td>
  88 </tr>
  89 <tr>
  90 <td>
  91                   <p>
  92                     egrep
  93                   </p>
  94                 </td>
  95 <td>
  96                   <p>
  97                     Yes
  98                   </p>
  99                 </td>
 100 <td>
 101                   <p>
 102                     Specifies that the grammar recognized by the regular expression
 103                     engine is the same as that used by POSIX utility grep when given
 104                     the -E option in IEEE Std 1003.1-2001, Portable Operating System
 105                     Interface (POSIX ), Shells and Utilities, Section 4, Utilities,
 106                     grep (FWD.1).
 107                   </p>
 108                   <p>
 109                     That is to say, the same as <a class="link" href="../../syntax/basic_extended.html" title="POSIX Extended Regular Expression Syntax">POSIX
 110                     extended syntax</a>, but with the newline character acting
 111                     as an alternation character in addition to "|".
 112                   </p>
 113                 </td>
 114 </tr>
 115 <tr>
 116 <td>
 117                   <p>
 118                     awk
 119                   </p>
 120                 </td>
 121 <td>
 122                   <p>
 123                     Yes
 124                   </p>
 125                 </td>
 126 <td>
 127                   <p>
 128                     Specifies that the grammar recognized by the regular expression
 129                     engine is the same as that used by POSIX utility awk in IEEE
 130                     Std 1003.1-2001, Portable Operating System Interface (POSIX ),
 131                     Shells and Utilities, Section 4, awk (FWD.1).
 132                   </p>
 133                   <p>
 134                     That is to say: the same as <a class="link" href="../../syntax/basic_extended.html" title="POSIX Extended Regular Expression Syntax">POSIX
 135                     extended syntax</a>, but with escape sequences in character
 136                     classes permitted.
 137                   </p>
 138                   <p>
 139                     In addition some perl-style escape sequences are supported (actually
 140                     the awk syntax only requires \a \b \t \v \f \n and \r to be recognised,
 141                     all other Perl-style escape sequences invoke undefined behavior
 142                     according to the POSIX standard, but are in fact recognised by
 143                     Boost.Regex).
 144                   </p>
 145                 </td>
 146 </tr>
 147 </tbody>
 148 </table></div>
 149 <p>
 150           The following options may also be set when using POSIX extended regular
 151           expressions:
 152         </p>
 153 <div class="informaltable"><table class="table">
 154 <colgroup>
 155 <col>
 156 <col>
 157 <col>
 158 </colgroup>
 159 <thead><tr>
 160 <th>
 161                   <p>
 162                     Element
 163                   </p>
 164                 </th>
 165 <th>
 166                   <p>
 167                     Standardized
 168                   </p>
 169                 </th>
 170 <th>
 171                   <p>
 172                     Effect when set
 173                   </p>
 174                 </th>
 175 </tr></thead>
 176 <tbody>
 177 <tr>
 178 <td>
 179                   <p>
 180                     icase
 181                   </p>
 182                 </td>
 183 <td>
 184                   <p>
 185                     Yes
 186                   </p>
 187                 </td>
 188 <td>
 189                   <p>
 190                     Specifies that matching of regular expressions against a character
 191                     container sequence shall be performed without regard to case.
 192                   </p>
 193                 </td>
 194 </tr>
 195 <tr>
 196 <td>
 197                   <p>
 198                     nosubs
 199                   </p>
 200                 </td>
 201 <td>
 202                   <p>
 203                     Yes
 204                   </p>
 205                 </td>
 206 <td>
 207                   <p>
 208                     Specifies that when a regular expression is matched against a
 209                     character container sequence, then no sub-expression matches
 210                     are to be stored in the supplied <a class="link" href="../match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a> structure.
 211                   </p>
 212                 </td>
 213 </tr>
 214 <tr>
 215 <td>
 216                   <p>
 217                     optimize
 218                   </p>
 219                 </td>
 220 <td>
 221                   <p>
 222                     Yes
 223                   </p>
 224                 </td>
 225 <td>
 226                   <p>
 227                     Specifies that the regular expression engine should pay more
 228                     attention to the speed with which regular expressions are matched,
 229                     and less to the speed with which regular expression objects are
 230                     constructed. Otherwise it has no detectable effect on the program
 231                     output. This currently has no effect for Boost.Regex.
 232                   </p>
 233                 </td>
 234 </tr>
 235 <tr>
 236 <td>
 237                   <p>
 238                     collate
 239                   </p>
 240                 </td>
 241 <td>
 242                   <p>
 243                     Yes
 244                   </p>
 245                 </td>
 246 <td>
 247                   <p>
 248                     Specifies that character ranges of the form <code class="computeroutput"><span class="special">[</span><span class="identifier">a</span><span class="special">-</span><span class="identifier">b</span><span class="special">]</span></code>
 249                     should be locale sensitive. This bit is on by default for POSIX-Extended
 250                     regular expressions, but can be unset to force ranges to be compared
 251                     by code point only.
 252                   </p>
 253                 </td>
 254 </tr>
 255 <tr>
 256 <td>
 257                   <p>
 258                     newline_alt
 259                   </p>
 260                 </td>
 261 <td>
 262                   <p>
 263                     No
 264                   </p>
 265                 </td>
 266 <td>
 267                   <p>
 268                     Specifies that the \n character has the same effect as the alternation
 269                     operator |. Allows newline separated lists to be used as a list
 270                     of alternatives.
 271                   </p>
 272                 </td>
 273 </tr>
 274 <tr>
 275 <td>
 276                   <p>
 277                     no_escape_in_lists
 278                   </p>
 279                 </td>
 280 <td>
 281                   <p>
 282                     No
 283                   </p>
 284                 </td>
 285 <td>
 286                   <p>
 287                     When set this makes the escape character ordinary inside lists,
 288                     so that <code class="computeroutput"><span class="special">[\</span><span class="identifier">b</span><span class="special">]</span></code> would match either '\' or 'b'.
 289                     This bit is on by default for POSIX-Extended regular expressions,
 290                     but can be unset to force escapes to be recognised inside lists.
 291                   </p>
 292                 </td>
 293 </tr>
 294 <tr>
 295 <td>
 296                   <p>
 297                     no_bk_refs
 298                   </p>
 299                 </td>
 300 <td>
 301                   <p>
 302                     No
 303                   </p>
 304                 </td>
 305 <td>
 306                   <p>
 307                     When set then backreferences are disabled. This bit is on by
 308                     default for POSIX-Extended regular expressions, but can be unset
 309                     to support for backreferences on.
 310                   </p>
 311                 </td>
 312 </tr>
 313 <tr>
 314 <td>
 315                   <p>
 316                     no_except
 317                   </p>
 318                 </td>
 319 <td>
 320                   <p>
 321                     No
 322                   </p>
 323                 </td>
 324 <td>
 325                   <p>
 326                     Prevents <a class="link" href="../basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a> from throwing
 327                     an exception when an invalid expression is encountered.
 328                   </p>
 329                 </td>
 330 </tr>
 331 <tr>
 332 <td>
 333                   <p>
 334                     save_subexpression_location
 335                   </p>
 336                 </td>
 337 <td>
 338                   <p>
 339                     No
 340                   </p>
 341                 </td>
 342 <td>
 343                   <p>
 344                     When set then the locations of individual sub-expressions within
 345                     the <span class="emphasis"><em>original regular expression string</em></span> can
 346                     be accessed via the <a class="link" href="../basic_regex.html#boost_regex.basic_regex.subexpression"><code class="computeroutput"><span class="identifier">subexpression</span><span class="special">()</span></code></a>
 347                     member function of <code class="computeroutput"><span class="identifier">basic_regex</span></code>.
 348                   </p>
 349                 </td>
 350 </tr>
 351 </tbody>
 352 </table></div>
 353 </div>
 354 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 355 <td align="left"></td>
 356 <td align="right"><div class="copyright-footer">Copyright &#169; 1998-2013 John Maddock<p>
 357         Distributed under the Boost Software License, Version 1.0. (See accompanying
 358         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>)
 359       </p>
 360 </div></td>
 361 </tr></table>
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