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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="boost_regex.ref.syntax_option_type.syntax_option_type_perl"></a><a class="link" href="syntax_option_type_perl.html" title="Options for Perl Regular Expressions"> |
| Options for Perl Regular Expressions</a> |
| </h4></div></div></div> |
| <p> |
| One of the following must always be set for perl regular expressions: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Element |
| </p> |
| </th> |
| <th> |
| <p> |
| Standardized |
| </p> |
| </th> |
| <th> |
| <p> |
| Effect when set |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| ECMAScript |
| </p> |
| </td> |
| <td> |
| <p> |
| Yes |
| </p> |
| </td> |
| <td> |
| <p> |
| Specifies that the grammar recognized by the regular expression |
| engine uses its normal semantics: that is the same as that given |
| in the ECMA-262, ECMAScript Language Specification, Chapter 15 |
| part 10, RegExp (Regular Expression) Objects (FWD.1). |
| </p> |
| <p> |
| This is functionally identical to the <a class="link" href="../../syntax/perl_syntax.html" title="Perl Regular Expression Syntax">Perl |
| regular expression syntax</a>. |
| </p> |
| <p> |
| Boost.Regex also recognizes all of the perl-compatible <code class="computeroutput"><span class="special">(?...)</span></code> extensions in this mode. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| perl |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| As above. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| normal |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| As above. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| JavaScript |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| As above. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| JScript |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| As above. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <p> |
| The following options may also be set when using perl-style regular expressions: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Element |
| </p> |
| </th> |
| <th> |
| <p> |
| Standardized |
| </p> |
| </th> |
| <th> |
| <p> |
| Effect when set |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| icase |
| </p> |
| </td> |
| <td> |
| <p> |
| Yes |
| </p> |
| </td> |
| <td> |
| <p> |
| Specifies that matching of regular expressions against a character |
| container sequence shall be performed without regard to case. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| nosubs |
| </p> |
| </td> |
| <td> |
| <p> |
| Yes |
| </p> |
| </td> |
| <td> |
| <p> |
| Specifies that when a regular expression is matched against a |
| character container sequence, then no sub-expression matches |
| 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. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| optimize |
| </p> |
| </td> |
| <td> |
| <p> |
| Yes |
| </p> |
| </td> |
| <td> |
| <p> |
| Specifies that the regular expression engine should pay more |
| attention to the speed with which regular expressions are matched, |
| and less to the speed with which regular expression objects are |
| constructed. Otherwise it has no detectable effect on the program |
| output. This currently has no effect for Boost.Regex. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| collate |
| </p> |
| </td> |
| <td> |
| <p> |
| Yes |
| </p> |
| </td> |
| <td> |
| <p> |
| 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> |
| should be locale sensitive. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| newline_alt |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Specifies that the \n character has the same effect as the alternation |
| operator |. Allows newline separated lists to be used as a list |
| of alternatives. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| no_except |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Prevents <a class="link" href="../basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a> from throwing |
| an exception when an invalid expression is encountered. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| no_mod_m |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Normally Boost.Regex behaves as if the Perl m-modifier is on: |
| so the assertions ^ and $ match after and before embedded newlines |
| respectively, setting this flags is equivalent to prefixing the |
| expression with (?-m). |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| no_mod_s |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Normally whether Boost.Regex will match "." against |
| a newline character is determined by the match flag <code class="computeroutput"><span class="identifier">match_dot_not_newline</span></code>. Specifying |
| this flag is equivalent to prefixing the expression with <code class="computeroutput"><span class="special">(?-</span><span class="identifier">s</span><span class="special">)</span></code> and therefore causes "." |
| not to match a newline character regardless of whether <code class="computeroutput"><span class="identifier">match_not_dot_newline</span></code> is set |
| in the match flags. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| mod_s |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Normally whether Boost.Regex will match "." against |
| a newline character is determined by the match flag <code class="computeroutput"><span class="identifier">match_dot_not_newline</span></code>. Specifying |
| this flag is equivalent to prefixing the expression with <code class="computeroutput"><span class="special">(?</span><span class="identifier">s</span><span class="special">)</span></code> and therefore causes "." |
| to match a newline character regardless of whether <code class="computeroutput"><span class="identifier">match_not_dot_newline</span></code> is set |
| in the match flags. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| mod_x |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| Turns on the perl x-modifier: causes unescaped whitespace in |
| the expression to be ignored. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| no_empty_expressions |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| When set then empty expressions/alternatives are prohibited. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| save_subexpression_location |
| </p> |
| </td> |
| <td> |
| <p> |
| No |
| </p> |
| </td> |
| <td> |
| <p> |
| When set then the locations of individual sub-expressions within |
| the <span class="emphasis"><em>original regular expression string</em></span> can |
| 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> |
| member function of <code class="computeroutput"><span class="identifier">basic_regex</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 1998 -2010 John Maddock<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
| </p> |
| </div></td> |
| </tr></table> |
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