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    <td width="85%" height="49"> <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Escape Character Parser</b></font></td>
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<p><a name="escape_char_parser"></a>The Escape Character Parser is a utility 
  parser, which parses escaped character sequences used in C/C++, 
  LEX or Perl regular expressions. Combined with the confix_p utility parser, it is useful for parsing C/C++ strings containing double quotes and other escaped 
  characters:</p>
<pre>    confix_p<span class="special">(</span><em class="literal">'"'</em><span class="special">,</span> <span class="special">*</span>c_escape_ch_p<span class="special">,</span> <em><span class="literal">'"</span></em><span class="literal"><em>'</em></span><span class="special">)</span></pre>
<p>There are two different types of the Escape Character Parser: 
  <tt>c_escape_ch_p</tt>, which parses C/C++ escaped character sequences and 
  <tt>lex_escape_ch_p</tt>, which parses LEX style escaped character sequences. 
  The following table shows the valid character sequences understood by these 
  utility parsers.</p>
<table width="90%" border="0" align="center">
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    <td colspan="2" class="table_title"><b>Summary of valid escaped character 
      sequences</b></td>
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    <td width="29%" height="27" class="table_cells"><b>c_escape_ch_p</b></td>
    <td width="71%" class="table_cells"><p><code>\b, \t, \n, \f, \r, \\, \&quot;, 
        \', \xHH, \OOO</code><br>
        where: H is some hexadecimal digit (0..9, a..f, A..F) and O is some octal 
        digit (0..7)</p></td>
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    <td height="27" class="table_cells"><strong>lex_escape_ch_p</strong></td>
    <td class="table_cells">
      <p>all C/C++ escaped character sequences as described above and additionally 
        any other character, which follows a backslash</p>
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<p>If there is a semantic action attached directly to the Escape Character Parser, 
  all valid escaped characters are converted to their character equivalent 
  (i.e. a backslash followed by a 'r' is converted to '\r'), which is 
  fed to the attached actor. The number of hexadecimal 
  or octal digits parsed depends on the size of one input character. An 
  overflow will be detected and will generate a non-match.  lex_escape_ch_p 
  will strip the leading backslash for all character 
  sequences which are not listed as valid C/C++ escape sequences when passing
  the unescaped character to an attached action.</p>
<p>Please note though, that if there is a semantic action attached to an 
  outermost parser (for instance as in <tt>(*c_escape_ch_p)[some_actor]</tt>, 
  where the action is attached to the kleene star generated parser) no conversion 
  takes place at the moment, but nevertheless the escaped characters are parsed 
  correctly. This limitation will be removed in a future version of the library.</p>
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<p class="copyright">Copyright &copy; 2001-2002 Daniel C. Nuffer<br>
Copyright &copy; 2003 Hartmut Kaiser <br>
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<font size="2">Use, modification and distribution is subject to the Boost Software
    License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
    http://www.boost.org/LICENSE_1_0.txt) </font> </p>
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