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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
+
+// ----------------------------------------------------------------------------
+// internals.hpp :  internal structs. included by format.hpp
+//                              stream_format_state, and format_item
+// ----------------------------------------------------------------------------
+
+
+#ifndef BOOST_FORMAT_INTERNALS_HPP
+#define BOOST_FORMAT_INTERNALS_HPP
+
+
+#include <string>
+#include <sstream>
+
+namespace boost {
+namespace io {
+namespace detail {
+
+
+// --------------
+// set of params that define the format state of a stream
+
+template<class Ch, class Tr> 
+struct stream_format_state 
+{
+  typedef BOOST_IO_STD basic_ios<Ch, Tr>   basic_ios;
+
+  std::streamsize width_;
+  std::streamsize precision_;
+  Ch fill_; 
+  std::ios_base::fmtflags flags_;
+
+  stream_format_state()       : width_(-1), precision_(-1), fill_(0), flags_(std::ios_base::dec)  {}
+  stream_format_state(basic_ios& os)                  {set_by_stream(os); }
+
+  void apply_on(basic_ios & os) const;                //- applies format_state to the stream
+  template<class T> void apply_manip(T manipulator)   //- modifies state by applying manipulator.
+       { apply_manip_body<Ch, Tr, T>( *this, manipulator) ; }
+  void reset();                                       //- sets to default state.
+  void set_by_stream(const basic_ios& os);            //- sets to os's state.
+};  
+
+
+
+// --------------
+// format_item : stores all parameters that can be defined by directives in the format-string
+
+template<class Ch, class Tr>  
+struct format_item 
+{     
+  enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 };
+
+  enum arg_values { argN_no_posit   = -1, // non-positional directive. argN will be set later.
+                    argN_tabulation = -2, // tabulation directive. (no argument read) 
+                    argN_ignored    = -3  // ignored directive. (no argument read)
+  };
+  typedef BOOST_IO_STD basic_ios<Ch, Tr>              basic_ios;
+  typedef detail::stream_format_state<Ch, Tr>         stream_format_state;
+  typedef std::basic_string<Ch, Tr>           string_t;
+  typedef BOOST_IO_STD basic_ostringstream<Ch, Tr>    internal_stream_t;
+
+
+  int         argN_;           //- argument number (starts at 0,  eg : %1 => argN=0)
+                               //  negative values are used for items that don't process
+                               //  an argument
+  string_t    res_;            //- result of the formatting of this item
+  string_t    appendix_;       //- piece of string between this item and the next
+
+  stream_format_state ref_state_;// set by parsing the format_string, is only affected by modify_item
+  stream_format_state state_;  // always same as ref_state, _unless_ modified by manipulators 'group(..)'
+
+  // non-stream format-state parameters
+  signed int truncate_;        //- is >=0 for directives like %.5s (take 5 chars from the string)
+  unsigned int pad_scheme_;    //- several possible padding schemes can mix. see pad_values
+
+  format_item() : argN_(argN_no_posit), truncate_(-1), pad_scheme_(0)  {}
+
+  void compute_states();      // sets states  according to truncate and pad_scheme.
+}; 
+
+
+
+// -----------------------------------------------------------
+// Definitions
+// -----------------------------------------------------------
+
+// --- stream_format_state:: -------------------------------------------
+template<class Ch, class Tr> inline
+void stream_format_state<Ch,Tr> ::apply_on(basic_ios & os) const
+  // set the state of this stream according to our params
+{
+      if(width_ != -1)
+        os.width(width_);
+      if(precision_ != -1)
+        os.precision(precision_);
+      if(fill_ != 0)
+        os.fill(fill_);
+      os.flags(flags_);
+}
+
+template<class Ch, class Tr>      inline
+void stream_format_state<Ch,Tr> ::set_by_stream(const basic_ios& os) 
+  // set our params according to the state of this stream
+{
+      flags_ = os.flags();
+      width_ = os.width();
+      precision_ = os.precision();
+      fill_ = os.fill();
+}
+
+template<class Ch, class Tr, class T>  inline
+void apply_manip_body( stream_format_state<Ch, Tr>& self,
+                       T manipulator) 
+  // modify our params according to the manipulator
+{
+      BOOST_IO_STD basic_stringstream<Ch, Tr>  ss;
+      self.apply_on( ss );
+      ss << manipulator;
+      self.set_by_stream( ss );
+}
+
+template<class Ch, class Tr> inline
+void stream_format_state<Ch,Tr> ::reset() 
+  // set our params to standard's default state
+{
+      width_=-1; precision_=-1; fill_=0; 
+      flags_ = std::ios_base::dec; 
+}
+
+
+// --- format_items:: -------------------------------------------
+template<class Ch, class Tr> inline
+void format_item<Ch, Tr> ::compute_states() 
+  // reflect pad_scheme_   on  state_ and ref_state_ 
+  //   because some pad_schemes has complex consequences on several state params.
+{
+  if(pad_scheme_ & zeropad) 
+  {
+    if(ref_state_.flags_ & std::ios_base::left) 
+    {
+      pad_scheme_ = pad_scheme_ & (~zeropad); // ignore zeropad in left alignment
+    }
+    else 
+    { 
+      ref_state_.fill_='0'; 
+      ref_state_.flags_ |= std::ios_base::internal;
+    }
+  }
+  state_ = ref_state_;
+}
+
+
+} } } // namespaces boost :: io :: detail
+
+
+#endif // BOOST_FORMAT_INTERNALS_HPP