Re: [Boost-users] [foreach] reverse foreach?

8 Mar 2006

      Andy Little wrote:
...
FWIW Heres some sample code. Its seems a bit lopsided!
std::ofstream out("toolpath_out.txt");
BOOST_FOREACH(boost::shared_ptr<section> sp,vect){
if (sp->m_action == section::reverse){
           for( std::vectorstd::string::reverse_iterator iter
                = sp->m_vector.rbegin();
                    iter != sp->m_vector.rend();
                        ++iter){
                out << *iter << '\n';
            }
        }
        else {
            BOOST_FOREACH(std::string str,sp->m_vector){
                out << str << '\n';
            }
        }
    }
Are there any plans for a BOOST_REVERSE_FOREACH?
I hear the new range library is under construction,
which will enable:

     BOOST_FOREACH (int x, vect|reversed) {

     }

A current workaround is maybe something like:

     template< class Range >
     boost::iterator_range<
         boost::reverse_iterator<
             typename boost::range_result_iterator<Range>::type
         >
     >
     make_reverse_range(Range& rng)
     {
         return boost::make_iterator_range(
             boost::make_reverse_iterator(boost::end(rng)),
             boost::make_reverse_iterator(boost::begin(rng))
         );
     }

     BOOST_FOREACH (int x, ::make_reverse_range(vect)) {

     }

-- 
Regards,
Shunsuke Sogame