Re: [Boost-bugs] [Boost C++ Libraries] #4020: regex::match_results::format functor cannot use member variables

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #4020: regex::match_results::format functor cannot use member variables
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-03-18 16:32:43

#4020: regex::match_results::format  functor cannot use member variables
--------------------------------------------------+-------------------------
  Reporter:  Keith MacDonald <keith@…>            |       Owner:  johnmaddock  
      Type:  Support Requests                     |      Status:  closed       
 Milestone:  Boost 1.43.0                         |   Component:  regex        
   Version:  Boost 1.42.0                         |    Severity:  Problem      
Resolution:  fixed                                |    Keywords:  regex functor
--------------------------------------------------+-------------------------

Comment(by Keith MacDonald <keith@…>):

 Thanks for the clarification.  Returning to C++ after a break, I had
 forgotten that it was a standard library convention to pass functors by
 value.  Anyway, I've amended my example code to take account of that, and
 you're welcome to use it in the documentation:

 {{{
 // Code to insert an incremented count before each word in the source
 text.

 #include <stdlib.h>
 #include <iostream>
 #include <sstream>
 #include <boost/regex.hpp>
 #include <boost/shared_ptr.hpp>

 typedef wchar_t         char_t;
 typedef std::wstring    string_t;

 template <class M>
 class functor
 {
 public:
     functor() : m_pImpl(new functor_data) {}

     template <class O>
     O operator()(const M& m, O i)
     {
         // Generate the sequence number in brackets:
         char_t  buf[16];
         O       i2(i);

         *i2++ = L'(';
         _itow(++m_pImpl->nCounter, buf, 10);
         i2 = std::copy(buf, buf + wcslen(buf), i2);
         *i2++ = L')';

         // Copy the matched text;
         return m.format(i2, L"$0");
     }

 private:
     struct functor_data
     {
         functor_data() : nCounter(0) {}
         int nCounter;
     };

     boost::shared_ptr<functor_data> m_pImpl;
 };

 int wmain(int argc, char_t* argv[])
 {
     string_t    sText(L"The quick brown fox jumped over the lazy dog");
     string_t    sRE(L"\\w+");

     boost::regex_constants::match_flag_type matchFlags =
         boost::regex_constants::match_default;

     boost::basic_regex<char_t> e;
     e.assign(sRE, matchFlags);

     typedef string_t::const_iterator        string_iterator;
     boost::regex_iterator<string_iterator>  reit(sText.begin(),
 sText.end(), e, matchFlags);
     boost::regex_iterator<string_iterator>  reEnd;
     boost::match_results<string_iterator>   last_m = *reit;
     std::basic_ostringstream<char_t>        stream;
     std::ostream_iterator<char_t, char_t>   streamIter(stream);

     functor<boost::match_results<string_iterator> > func;

     for ( ; reit != reEnd; ++reit) {
         const boost::match_results<string_iterator>&    m = *reit;

         // copy the source up to this match:
         std::copy(m.prefix().first, m.prefix().second, streamIter);

         // replace the matched text:
         m.format(streamIter, func);
         last_m = m;
     }

     // copy the remainder of the source string:
     std::copy(last_m.suffix().first, last_m.suffix().second, streamIter);

     // output the result:
     std::wcout << stream.str() << std::endl;

     return 0;
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4020#comment:4>
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