text: // ----------------------------------------------------------------------------
  //  feed_args.hpp :  functions for processing each argument 
  //                      (feed, feed_manip, and distribute)
  // ----------------------------------------------------------------------------
  
  //  Copyright Samuel Krempp 2003. Use, modification, and distribution are
  //  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)
  
  //  See http://www.boost.org/libs/format for library home page
  
  // ----------------------------------------------------------------------------
  
  #ifndef BOOST_FORMAT_FEED_ARGS_HPP
  #define BOOST_FORMAT_FEED_ARGS_HPP
  
  #include <boost/config.hpp>
  #include <boost/assert.hpp>
  #include <boost/throw_exception.hpp>
  
  #include <boost/format/format_class.hpp>
  #include <boost/format/group.hpp>
  #include <boost/format/detail/msvc_disambiguater.hpp>
  
  namespace boost {
  namespace io {
  namespace detail {
  
      template<class Ch, class Tr, class Alloc>
      void mk_str( std::basic_string<Ch,Tr, Alloc> & res, 
                   const Ch * beg,
                   typename std::basic_string<Ch,Tr,Alloc>::size_type size,
                   std::streamsize w, 
                   const Ch fill_char,
                   std::ios_base::fmtflags f, 
                   const Ch prefix_space, // 0 if no space-padding
                   bool center) 
      // applies centered/left/right  padding  to the string  [beg, beg+size[
      // Effects : the result is placed in res.
      {
          typedef typename std::basic_string<Ch,Tr,Alloc>::size_type size_type;
          res.resize(0);
          if(w<=0 || static_cast<size_type>(w) <=size) {
              // no need to pad.
              res.reserve(size + !!prefix_space);
              if(prefix_space) 
                res.append(1, prefix_space);
              if (size)
                res.append(beg, size);
          }
          else { 
              std::streamsize n=static_cast<std::streamsize>(w-size-!!prefix_space);
              std::streamsize n_after = 0, n_before = 0; 
              res.reserve(static_cast<size_type>(w)); // allocate once for the 2 inserts
              if(center) 
                  n_after = n/2, n_before = n - n_after; 
              else 
                  if(f & std::ios_base::left)
                      n_after = n;
                  else
                      n_before = n;
              // now make the res string :
              if(n_before) res.append(static_cast<size_type>(n_before), fill_char);
              if(prefix_space) 
                res.append(1, prefix_space);
              if (size)  
                res.append(beg, size);
              if(n_after) res.append(static_cast<size_type>(n_after), fill_char);
          }
      } // -mk_str(..) 
  
  
  #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300) || \
      BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
  // MSVC needs to be tricked to disambiguate this simple overload..
  // the trick is in "boost/format/msvc_disambiguater.hpp"
    
      template< class Ch, class Tr, class T> inline
      void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
          disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
      }
      template< class Ch, class Tr, class T> inline
      void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
          disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
      }
  
  #else  
  
      template< class Ch, class Tr, class T> inline
      void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
      }
  
      template< class Ch, class Tr, class T> inline
      void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
          os << group_head(x.a1_); // send the first N-1 items, not the last
      }
  
      template< class Ch, class Tr, class T> inline
      void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
          os << x ;
      }
  
      template< class Ch, class Tr, class T> inline
      void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
          os << group_last(x.a1_); // this selects the last element
      }
  
  #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST 
      template< class Ch, class Tr, class T> inline
      void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
      }
  
      template< class Ch, class Tr, class T> inline
      void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
          os << x ;
      }
  #endif
  #endif  // -msvc workaround
  
      template< class Ch, class Tr, class T>
      void call_put_head(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x) {
          put_head(os, *(typename ::boost::remove_reference<T>::type*)x);
      }
  
      template< class Ch, class Tr, class T>
      void call_put_last(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x) {
          put_last(os, *(T*)x);
      }
  
      template< class Ch, class Tr>
      struct put_holder {
          template<class T>
          put_holder(T& t)
            : arg(&t),
              put_head(&call_put_head<Ch, Tr, T>),
              put_last(&call_put_last<Ch, Tr, T>)
          {}
          const void* arg;
          void (*put_head)(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x);
          void (*put_last)(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x);
      };
      
      template< class Ch, class Tr> inline
      void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const put_holder<Ch, Tr>& t) {
          t.put_head(os, t.arg);
      }
      
      template< class Ch, class Tr> inline
      void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const put_holder<Ch, Tr>& t) {
          t.put_last(os, t.arg);
      }
  
  
      template< class Ch, class Tr, class Alloc, class T> 
      void put( T x, 
                const format_item<Ch, Tr, Alloc>& specs, 
                typename basic_format<Ch, Tr, Alloc>::string_type& res, 
                typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
                io::detail::locale_t *loc_p = NULL)
      {
  #ifdef BOOST_MSVC
         // If std::min<unsigned> or std::max<unsigned> are already instantiated
         // at this point then we get a blizzard of warning messages when we call
         // those templates with std::size_t as arguments.  Weird and very annoyning...
  #pragma warning(push)
  #pragma warning(disable:4267)
  #endif
          // does the actual conversion of x, with given params, into a string
          // using the supplied stringbuf.
  
          typedef typename basic_format<Ch, Tr, Alloc>::string_type   string_type;
          typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
          typedef typename string_type::size_type size_type;
  
          basic_oaltstringstream<Ch, Tr, Alloc>  oss( &buf);
          specs.fmtstate_.apply_on(oss, loc_p);
  
          // the stream format state can be modified by manipulators in the argument :
          put_head( oss, x );
          // in case x is a group, apply the manip part of it, 
          // in order to find width
  
          const std::ios_base::fmtflags fl=oss.flags();
          const bool internal = (fl & std::ios_base::internal) != 0;
          const std::streamsize w = oss.width();
          const bool two_stepped_padding= internal && (w!=0);
        
          res.resize(0);
          if(! two_stepped_padding) {
              if(w>0) // handle padding via mk_str, not natively in stream 
                  oss.width(0);
              put_last( oss, x);
              const Ch * res_beg = buf.pbase();
              Ch prefix_space = 0;
              if(specs.pad_scheme_ & format_item_t::spacepad)
                  if(buf.pcount()== 0 || 
                     (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
                      prefix_space = oss.widen(' ');
              size_type res_size = (std::min)(
                  static_cast<size_type>(specs.truncate_ - !!prefix_space), 
                  buf.pcount() );
              mk_str(res, res_beg, res_size, w, oss.fill(), fl, 
                     prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
          }
          else  { // 2-stepped padding
              // internal can be implied by zeropad, or user-set.
              // left, right, and centered alignment overrule internal,
              // but spacepad or truncate might be mixed with internal (using manipulator)
              put_last( oss, x); // may pad
              const Ch * res_beg = buf.pbase();
              size_type res_size = buf.pcount();
              bool prefix_space=false;
              if(specs.pad_scheme_ & format_item_t::spacepad)
                  if(buf.pcount()== 0 || 
                     (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
                      prefix_space = true;
              if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
                  // okay, only one thing was printed and padded, so res is fine
                  res.assign(res_beg, res_size);
              }
              else { //   length w exceeded
                  // either it was multi-output with first output padding up all width..
                  // either it was one big arg and we are fine.
                  // Note that res_size<w is possible  (in case of bad user-defined formatting)
                  res.assign(res_beg, res_size);
                  res_beg=NULL;  // invalidate pointers.
                  
                  // make a new stream, to start re-formatting from scratch :
                  buf.clear_buffer();
                  basic_oaltstringstream<Ch, Tr, Alloc>  oss2( &buf);
                  specs.fmtstate_.apply_on(oss2, loc_p);
                  put_head( oss2, x );
  
                  oss2.width(0);
                  if(prefix_space)
                      oss2 << ' ';
                  put_last(oss2, x );
                  if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
                      prefix_space =true;
                      oss2 << ' ';
                  }
                  // we now have the minimal-length output
                  const Ch * tmp_beg = buf.pbase();
                  size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_),
                                                  buf.pcount() );
                                                      
                  
                  if(static_cast<size_type>(w) <= tmp_size) { 
                      // minimal length is already >= w, so no padding (cool!)
                          res.assign(tmp_beg, tmp_size);
                  }
                  else { // hum..  we need to pad (multi_output, or spacepad present)
                      //find where we should pad
                      size_type sz = (std::min)(res_size + (prefix_space ? 1 : 0), tmp_size);
                      size_type i = prefix_space;
                      for(; i<sz && tmp_beg[i] == res[i - (prefix_space ? 1 : 0)]; ++i) {}
                      if(i>=tmp_size) i=prefix_space;
                      res.assign(tmp_beg, i);
                                          std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
                                          BOOST_ASSERT(d>0);
                      res.append(static_cast<size_type>( d ), oss2.fill());
                      res.append(tmp_beg+i, tmp_size-i);
                      BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0) 
                                   == static_cast<size_type>(w));
                      BOOST_ASSERT(res.size() == static_cast<size_type>(w));
                  }
              }
          }
          buf.clear_buffer();
  #ifdef BOOST_MSVC
  #pragma warning(pop)
  #endif
      } // end- put(..)
  
  
      template< class Ch, class Tr, class Alloc, class T> 
      void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
          // call put(x, ..) on every occurence of the current argument :
          if(self.cur_arg_ >= self.num_args_)  {
              if( self.exceptions() & too_many_args_bit )
                  boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_)); 
              else return;
          }
          for(unsigned long i=0; i < self.items_.size(); ++i) {
              if(self.items_[i].argN_ == self.cur_arg_) {
                  put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_, 
                                  self.buf_, boost::get_pointer(self.loc_) );
              }
          }
      }
  
      template<class Ch, class Tr, class Alloc, class T> 
      basic_format<Ch, Tr, Alloc>&  
      feed_impl (basic_format<Ch,Tr, Alloc>& self, T x) {
          if(self.dumped_) self.clear();
          distribute<Ch, Tr, Alloc, T> (self, x);
          ++self.cur_arg_;
          if(self.bound_.size() != 0) {
                  while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
                      ++self.cur_arg_;
          }
          return self;
      }
  
      template<class Ch, class Tr, class Alloc, class T> inline
      basic_format<Ch, Tr, Alloc>&  
      feed (basic_format<Ch,Tr, Alloc>& self, T x) {
          return feed_impl<Ch, Tr, Alloc, const put_holder<Ch, Tr>&>(self, put_holder<Ch, Tr>(x));
      }
      
  } // namespace detail
  } // namespace io
  } // namespace boost
  
  
  #endif //  BOOST_FORMAT_FEED_ARGS_HPP
  