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    1 // ----------------------------------------------------------------------------
    2 //  feed_args.hpp :  functions for processing each argument
    3 //                      (feed, feed_manip, and distribute)
    4 // ----------------------------------------------------------------------------
    5 
    6 //  Copyright Samuel Krempp 2003. Use, modification, and distribution are
    7 //  subject to the Boost Software License, Version 1.0. (See accompanying
    8 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    9 
   10 //  See http://www.boost.org/libs/format for library home page
   11 
   12 // ----------------------------------------------------------------------------
   13 
   14 #ifndef BOOST_FORMAT_FEED_ARGS_HPP
   15 #define BOOST_FORMAT_FEED_ARGS_HPP
   16 
   17 #include <boost/config.hpp>
   18 #include <boost/assert.hpp>
   19 #include <boost/throw_exception.hpp>
   20 
   21 #include <boost/format/format_class.hpp>
   22 #include <boost/format/group.hpp>
   23 #include <boost/format/detail/msvc_disambiguater.hpp>
   24 
   25 namespace boost {
   26 namespace io {
   27 namespace detail {
   28 
   29     template<class Ch, class Tr, class Alloc>
   30     void mk_str( std::basic_string<Ch,Tr, Alloc> & res,
   31                  const Ch * beg,
   32                  typename std::basic_string<Ch,Tr,Alloc>::size_type size,
   33                  std::streamsize w,
   34                  const Ch fill_char,
   35                  std::ios_base::fmtflags f,
   36                  const Ch prefix_space, // 0 if no space-padding
   37                  bool center)
   38     // applies centered/left/right  padding  to the string  [beg, beg+size[
   39     // Effects : the result is placed in res.
   40     {
   41         typedef typename std::basic_string<Ch,Tr,Alloc>::size_type size_type;
   42         res.resize(0);
   43         if(w<=0 || static_cast<size_type>(w) <=size) {
   44             // no need to pad.
   45             res.reserve(size + !!prefix_space);
   46             if(prefix_space)
   47               res.append(1, prefix_space);
   48             if (size)
   49               res.append(beg, size);
   50         }
   51         else {
   52             std::streamsize n=static_cast<std::streamsize>(w-size-!!prefix_space);
   53             std::streamsize n_after = 0, n_before = 0;
   54             res.reserve(w); // allocate once for the 2 inserts
   55             if(center)
   56                 n_after = n/2, n_before = n - n_after;
   57             else
   58                 if(f & std::ios_base::left)
   59                     n_after = n;
   60                 else
   61                     n_before = n;
   62             // now make the res string :
   63             if(n_before) res.append(n_before, fill_char);
   64             if(prefix_space)
   65               res.append(1, prefix_space);
   66             if (size)
   67               res.append(beg, size);
   68             if(n_after) res.append(n_after, fill_char);
   69         }
   70     } // -mk_str(..)
   71 
   72 
   73 #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300) || \
   74     BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
   75 // MSVC needs to be tricked to disambiguate this simple overload..
   76 // the trick is in "boost/format/msvc_disambiguater.hpp"
   77 
   78     template< class Ch, class Tr, class T> inline
   79     void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
   80         disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
   81     }
   82     template< class Ch, class Tr, class T> inline
   83     void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
   84         disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
   85     }
   86 
   87 #else
   88 
   89     template< class Ch, class Tr, class T> inline
   90     void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
   91     }
   92 
   93     template< class Ch, class Tr, class T> inline
   94     void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
   95         os << group_head(x.a1_); // send the first N-1 items, not the last
   96     }
   97 
   98     template< class Ch, class Tr, class T> inline
   99     void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
  100         os << x ;
  101     }
  102 
  103     template< class Ch, class Tr, class T> inline
  104     void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
  105         os << group_last(x.a1_); // this selects the last element
  106     }
  107 
  108 #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST
  109     template< class Ch, class Tr, class T> inline
  110     void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
  111     }
  112 
  113     template< class Ch, class Tr, class T> inline
  114     void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
  115         os << x ;
  116     }
  117 #endif
  118 #endif  // -msvc workaround
  119 
  120 
  121     template< class Ch, class Tr, class Alloc, class T>
  122     void put( T x,
  123               const format_item<Ch, Tr, Alloc>& specs,
  124               typename basic_format<Ch, Tr, Alloc>::string_type& res,
  125               typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
  126               io::detail::locale_t *loc_p = NULL)
  127     {
  128         // does the actual conversion of x, with given params, into a string
  129         // using the supplied stringbuf.
  130 
  131         typedef typename basic_format<Ch, Tr, Alloc>::string_type   string_type;
  132         typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
  133         typedef typename string_type::size_type size_type;
  134 
  135         basic_oaltstringstream<Ch, Tr, Alloc>  oss( &buf);
  136         specs.fmtstate_.apply_on(oss, loc_p);
  137 
  138         // the stream format state can be modified by manipulators in the argument :
  139         put_head( oss, x );
  140         // in case x is a group, apply the manip part of it,
  141         // in order to find width
  142 
  143         const std::ios_base::fmtflags fl=oss.flags();
  144         const bool internal = (fl & std::ios_base::internal) != 0;
  145         const std::streamsize w = oss.width();
  146         const bool two_stepped_padding= internal && (w!=0);
  147 
  148         res.resize(0);
  149         if(! two_stepped_padding) {
  150             if(w>0) // handle padding via mk_str, not natively in stream
  151                 oss.width(0);
  152             put_last( oss, x);
  153             const Ch * res_beg = buf.pbase();
  154             Ch prefix_space = 0;
  155             if(specs.pad_scheme_ & format_item_t::spacepad)
  156                 if(buf.pcount()== 0 ||
  157                    (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
  158                     prefix_space = oss.widen(' ');
  159             size_type res_size = (std::min)(
  160                 static_cast<size_type>(specs.truncate_ - !!prefix_space),
  161                 buf.pcount() );
  162             mk_str(res, res_beg, res_size, w, oss.fill(), fl,
  163                    prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
  164         }
  165         else  { // 2-stepped padding
  166             // internal can be implied by zeropad, or user-set.
  167             // left, right, and centered alignment overrule internal,
  168             // but spacepad or truncate might be mixed with internal (using manipulator)
  169             put_last( oss, x); // may pad
  170             const Ch * res_beg = buf.pbase();
  171             size_type res_size = buf.pcount();
  172             bool prefix_space=false;
  173             if(specs.pad_scheme_ & format_item_t::spacepad)
  174                 if(buf.pcount()== 0 ||
  175                    (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
  176                     prefix_space = true;
  177             if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
  178                 // okay, only one thing was printed and padded, so res is fine
  179                 res.assign(res_beg, res_size);
  180             }
  181             else { //   length w exceeded
  182                 // either it was multi-output with first output padding up all width..
  183                 // either it was one big arg and we are fine.
  184                 // Note that res_size<w is possible  (in case of bad user-defined formatting)
  185                 res.assign(res_beg, res_size);
  186                 res_beg=NULL;  // invalidate pointers.
  187 
  188                 // make a new stream, to start re-formatting from scratch :
  189                 buf.clear_buffer();
  190                 basic_oaltstringstream<Ch, Tr, Alloc>  oss2( &buf);
  191                 specs.fmtstate_.apply_on(oss2, loc_p);
  192                 put_head( oss2, x );
  193 
  194                 oss2.width(0);
  195                 if(prefix_space)
  196                     oss2 << ' ';
  197                 put_last(oss2, x );
  198                 if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
  199                     prefix_space =true;
  200                     oss2 << ' ';
  201                 }
  202                 // we now have the minimal-length output
  203                 const Ch * tmp_beg = buf.pbase();
  204                 size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_),
  205                                                 buf.pcount() );
  206 
  207 
  208                 if(static_cast<size_type>(w) <= tmp_size) {
  209                     // minimal length is already >= w, so no padding (cool!)
  210                         res.assign(tmp_beg, tmp_size);
  211                 }
  212                 else { // hum..  we need to pad (multi_output, or spacepad present)
  213                     //find where we should pad
  214                     size_type sz = (std::min)(res_size+prefix_space, tmp_size);
  215                     size_type i = prefix_space;
  216                     for(; i<sz && tmp_beg[i] == res[i-prefix_space]; ++i) {}
  217                     if(i>=tmp_size) i=prefix_space;
  218                     res.assign(tmp_beg, i);
  219                                         std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
  220                                         BOOST_ASSERT(d>0);
  221                     res.append(static_cast<size_type>( d ), oss2.fill());
  222                     res.append(tmp_beg+i, tmp_size-i);
  223                     BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0)
  224                                  == static_cast<size_type>(w));
  225                     BOOST_ASSERT(res.size() == static_cast<size_type>(w));
  226                 }
  227             }
  228         }
  229         buf.clear_buffer();
  230     } // end- put(..)
  231 
  232 
  233     template< class Ch, class Tr, class Alloc, class T>
  234     void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
  235         // call put(x, ..) on every occurence of the current argument :
  236         if(self.cur_arg_ >= self.num_args_)  {
  237             if( self.exceptions() & too_many_args_bit )
  238                 boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_));
  239             else return;
  240         }
  241         for(unsigned long i=0; i < self.items_.size(); ++i) {
  242             if(self.items_[i].argN_ == self.cur_arg_) {
  243                 put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
  244                                 self.buf_, boost::get_pointer(self.loc_) );
  245             }
  246         }
  247     }
  248 
  249     template<class Ch, class Tr, class Alloc, class T>
  250     basic_format<Ch, Tr, Alloc>&
  251     feed (basic_format<Ch,Tr, Alloc>& self, T x) {
  252         if(self.dumped_) self.clear();
  253         distribute<Ch, Tr, Alloc, T> (self, x);
  254         ++self.cur_arg_;
  255         if(self.bound_.size() != 0) {
  256                 while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
  257                     ++self.cur_arg_;
  258         }
  259         return self;
  260     }
  261 
  262 } // namespace detail
  263 } // namespace io
  264 } // namespace boost
  265 
  266 
  267 #endif //  BOOST_FORMAT_FEED_ARGS_HPP