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+// -*- C++ -*-
+//  Boost general library 'format'   ---------------------------
+//  See http://www.boost.org for updates, documentation, and revision history.
+
+//  (C) Samuel Krempp 2001
+//                  krempp@crans.ens-cachan.fr
+//  Permission to copy, use, modify, sell and
+//  distribute this software is granted provided this copyright notice appears
+//  in all copies. This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+
+// ideas taken from Rüdiger Loos's format class
+// and Karl Nelson's ofstream
+
+// ----------------------------------------------------------------------------
+// feed_args.hpp :  functions for processing each argument 
+//                      (feed, feed_manip, and distribute)
+// ----------------------------------------------------------------------------
+
+
+#ifndef BOOST_FORMAT_FEED_ARGS_HPP
+#define BOOST_FORMAT_FEED_ARGS_HPP
+
+#include "boost/format/format_class.hpp"
+#include "boost/format/group.hpp"
+
+//#include "boost/throw_exception.hpp"
+
+namespace boost {
+namespace io {
+namespace detail {
+namespace  { 
+
+  inline
+  void empty_buf(BOOST_IO_STD ostringstream & os) { 
+    static const std::string emptyStr;
+    os.str(emptyStr); 
+  }
+
+  void do_pad( std::string & s, 
+                std::streamsize w, 
+                const char c, 
+                std::ios::fmtflags f, 
+                bool center) 
+    // applies centered / left / right  padding  to the string s.
+    // Effects : string s is padded.
+  {
+    std::streamsize n=w-s.size();
+    if(n<=0) {
+      return;
+    }
+    if(center) 
+      {
+        s.reserve(w); // allocate once for the 2 inserts
+        const std::streamsize n1 = n /2, n0 = n - n1; 
+        s.insert(s.begin(), n0, c);
+        s.append(n1, c);
+      } 
+    else 
+      {
+        if(f & std::ios::left) {
+          s.append(n, c);
+        }
+        else {
+          s.insert(s.begin(), n, c);
+        }
+      }
+  } // -do_pad(..) 
+
+
+  template<class T> inline
+  void put_head(BOOST_IO_STD ostream& , const T& ) {
+  }
+
+  template<class T> inline
+  void put_head( BOOST_IO_STD ostream& os, const group1<T>& x ) {
+    os << group_head(x.a1_); // send the first N-1 items, not the last
+  }
+
+  template<class T> inline
+  void put_last( BOOST_IO_STD ostream& os, const T& x ) {
+    os << x ;
+  }
+
+  template<class T> inline
+  void put_last( BOOST_IO_STD ostream& os, const group1<T>& x ) {
+    os << group_last(x.a1_); // this selects the last element
+  }
+
+#ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST 
+  template<class T> inline
+  void put_head( BOOST_IO_STD ostream& , T& ) {
+  }
+
+  template<class T> inline
+  void put_last( BOOST_IO_STD ostream& os, T& x ) {
+    os << x ;
+  }
+#endif
+
+
+
+  
+template<class T> 
+void put( T x, 
+          const format_item& specs, 
+          std::string & res, 
+          BOOST_IO_STD ostringstream& oss_ )
+{
+  // does the actual conversion of x, with given params, into a string
+  // using the *supplied* strinstream. (the stream state is important)
+
+  typedef std::string string_t;
+  typedef format_item  format_item_t;
+
+  stream_format_state   prev_state(oss_);
+    
+  specs.state_.apply_on(oss_);
+
+  // in case x is a group, apply the manip part of it, 
+  // in order to find width
+  put_head( oss_, x );
+  empty_buf( oss_);
+
+  const std::streamsize w=oss_.width();
+  const std::ios::fmtflags fl=oss_.flags();
+  const bool internal = (fl & std::ios::internal) != 0;
+  const bool two_stepped_padding = internal
+    &&  ! ( specs.pad_scheme_ & format_item_t::spacepad ) 
+    && specs.truncate_ < 0 ;
+      
+
+  if(! two_stepped_padding) 
+    {
+      if(w>0) // handle simple padding via do_pad, not natively in stream 
+        oss_.width(0);
+      put_last( oss_, x);
+      res = oss_.str();
+
+      if (specs.truncate_ >= 0)
+        res.erase(specs.truncate_);
+
+      // complex pads :
+      if(specs.pad_scheme_ & format_item_t::spacepad)
+        {
+          if( res.size()==0 ||   ( res[0]!='+' && res[0]!='-'  ))
+            {
+              res.insert(res.begin(), 1, ' '); // insert 1 space at  pos 0
+            }
+        }
+      if(w > 0) // need do_pad
+        {
+          do_pad(res,w,oss_.fill(), fl, (specs.pad_scheme_ & format_item_t::centered) !=0 );
+        }
+    } 
+  else  // 2-stepped padding
+    {
+      put_last( oss_, x); // oss_.width() may result in padding.
+      res = oss_.str();
+      
+      if (specs.truncate_ >= 0)
+        res.erase(specs.truncate_);
+
+      if( res.size() - w > 0)
+        { //   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.
+          empty_buf( oss_);
+          oss_.width(0);
+          put_last(oss_, x );
+          string_t tmp = oss_.str();  // minimal-length output
+          std::streamsize d;
+          if( (d=w - tmp.size()) <=0 ) 
+            {
+              // minimal length is already >= w, so no padding  (cool!)
+              res.swap(tmp);
+            }
+          else
+            { // hum..  we need to pad (it was necessarily multi-output)
+              typedef typename string_t::size_type size_type;
+              size_type i = 0;
+              while( i<tmp.size() && tmp[i] == res[i] ) // find where we should pad.
+                ++i;
+              tmp.insert(i, static_cast<size_type>( d ), oss_.fill());
+              res.swap( tmp );
+            }
+        }
+      else 
+        { // okay, only one thing was printed and padded, so res is fine.
+        }
+    }
+
+  prev_state.apply_on(oss_);
+  empty_buf( oss_);
+  oss_.clear();
+} // end- put(..)
+
+
+}  // local namespace
+
+
+
+
+
+template<class T> 
+void distribute(basic_format& 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()); // too many variables have been supplied !
+      else return;
+    }
+  for(unsigned long i=0; i < self.items_.size(); ++i)
+    {
+      if(self.items_[i].argN_ == self.cur_arg_)
+        {
+          put<T> (x, self.items_[i], self.items_[i].res_, self.oss_ );
+        }
+    }
+}
+
+template<class T> 
+basic_format&  feed(basic_format& self, T x) 
+{
+  if(self.dumped_) self.clear();
+  distribute<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_;
+    }
+
+  // this arg is finished, reset the stream's format state
+  self.state0_.apply_on(self.oss_);
+  return self;
+}
+    
+
+} // namespace detail
+} // namespace io
+} // namespace boost
+
+
+#endif //  BOOST_FORMAT_FEED_ARGS_HPP