boost/format/feed_args.hpp

   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(static_cast<size_type>(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(static_cast<size_type>(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(static_cast<size_type>(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 #ifdef BOOST_MSVC
 129        // If std::min<unsigned> or std::max<unsigned> are already instantiated
 130        // at this point then we get a blizzard of warning messages when we call
 131        // those templates with std::size_t as arguments.  Weird and very annoyning...
 132 #pragma warning(push)
 133 #pragma warning(disable:4267)
 134 #endif
 135         // does the actual conversion of x, with given params, into a string
 136         // using the supplied stringbuf.
 137
 138         typedef typename basic_format<Ch, Tr, Alloc>::string_type   string_type;
 139         typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
 140         typedef typename string_type::size_type size_type;
 141
 142         basic_oaltstringstream<Ch, Tr, Alloc>  oss( &buf);
 143         specs.fmtstate_.apply_on(oss, loc_p);
 144
 145         // the stream format state can be modified by manipulators in the argument :
 146         put_head( oss, x );
 147         // in case x is a group, apply the manip part of it,
 148         // in order to find width
 149
 150         const std::ios_base::fmtflags fl=oss.flags();
 151         const bool internal = (fl & std::ios_base::internal) != 0;
 152         const std::streamsize w = oss.width();
 153         const bool two_stepped_padding= internal && (w!=0);
 154
 155         res.resize(0);
 156         if(! two_stepped_padding) {
 157             if(w>0) // handle padding via mk_str, not natively in stream
 158                 oss.width(0);
 159             put_last( oss, x);
 160             const Ch * res_beg = buf.pbase();
 161             Ch prefix_space = 0;
 162             if(specs.pad_scheme_ & format_item_t::spacepad)
 163                 if(buf.pcount()== 0 ||
 164                    (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
 165                     prefix_space = oss.widen(' ');
 166             size_type res_size = (std::min)(
 167                 static_cast<size_type>(specs.truncate_ - !!prefix_space),
 168                 buf.pcount() );
 169             mk_str(res, res_beg, res_size, w, oss.fill(), fl,
 170                    prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
 171         }
 172         else  { // 2-stepped padding
 173             // internal can be implied by zeropad, or user-set.
 174             // left, right, and centered alignment overrule internal,
 175             // but spacepad or truncate might be mixed with internal (using manipulator)
 176             put_last( oss, x); // may pad
 177             const Ch * res_beg = buf.pbase();
 178             size_type res_size = buf.pcount();
 179             bool prefix_space=false;
 180             if(specs.pad_scheme_ & format_item_t::spacepad)
 181                 if(buf.pcount()== 0 ||
 182                    (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-')  ))
 183                     prefix_space = true;
 184             if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
 185                 // okay, only one thing was printed and padded, so res is fine
 186                 res.assign(res_beg, res_size);
 187             }
 188             else { //   length w exceeded
 189                 // either it was multi-output with first output padding up all width..
 190                 // either it was one big arg and we are fine.
 191                 // Note that res_size<w is possible  (in case of bad user-defined formatting)
 192                 res.assign(res_beg, res_size);
 193                 res_beg=NULL;  // invalidate pointers.
 194
 195                 // make a new stream, to start re-formatting from scratch :
 196                 buf.clear_buffer();
 197                 basic_oaltstringstream<Ch, Tr, Alloc>  oss2( &buf);
 198                 specs.fmtstate_.apply_on(oss2, loc_p);
 199                 put_head( oss2, x );
 200
 201                 oss2.width(0);
 202                 if(prefix_space)
 203                     oss2 << ' ';
 204                 put_last(oss2, x );
 205                 if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
 206                     prefix_space =true;
 207                     oss2 << ' ';
 208                 }
 209                 // we now have the minimal-length output
 210                 const Ch * tmp_beg = buf.pbase();
 211                 size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_),
 212                                                 buf.pcount() );
 213
 214
 215                 if(static_cast<size_type>(w) <= tmp_size) {
 216                     // minimal length is already >= w, so no padding (cool!)
 217                         res.assign(tmp_beg, tmp_size);
 218                 }
 219                 else { // hum..  we need to pad (multi_output, or spacepad present)
 220                     //find where we should pad
 221                     size_type sz = (std::min)(res_size + (prefix_space ? 1 : 0), tmp_size);
 222                     size_type i = prefix_space;
 223                     for(; i<sz && tmp_beg[i] == res[i - (prefix_space ? 1 : 0)]; ++i) {}
 224                     if(i>=tmp_size) i=prefix_space;
 225                     res.assign(tmp_beg, i);
 226                                         std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
 227                                         BOOST_ASSERT(d>0);
 228                     res.append(static_cast<size_type>( d ), oss2.fill());
 229                     res.append(tmp_beg+i, tmp_size-i);
 230                     BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0)
 231                                  == static_cast<size_type>(w));
 232                     BOOST_ASSERT(res.size() == static_cast<size_type>(w));
 233                 }
 234             }
 235         }
 236         buf.clear_buffer();
 237 #ifdef BOOST_MSVC
 238 #pragma warning(pop)
 239 #endif
 240     } // end- put(..)
 241
 242
 243     template< class Ch, class Tr, class Alloc, class T>
 244     void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
 245         // call put(x, ..) on every occurence of the current argument :
 246         if(self.cur_arg_ >= self.num_args_)  {
 247             if( self.exceptions() & too_many_args_bit )
 248                 boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_));
 249             else return;
 250         }
 251         for(unsigned long i=0; i < self.items_.size(); ++i) {
 252             if(self.items_[i].argN_ == self.cur_arg_) {
 253                 put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
 254                                 self.buf_, boost::get_pointer(self.loc_) );
 255             }
 256         }
 257     }
 258
 259     template<class Ch, class Tr, class Alloc, class T>
 260     basic_format<Ch, Tr, Alloc>&
 261     feed (basic_format<Ch,Tr, Alloc>& self, T x) {
 262         if(self.dumped_) self.clear();
 263         distribute<Ch, Tr, Alloc, T> (self, x);
 264         ++self.cur_arg_;
 265         if(self.bound_.size() != 0) {
 266                 while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
 267                     ++self.cur_arg_;
 268         }
 269         return self;
 270     }
 271
 272 } // namespace detail
 273 } // namespace io
 274 } // namespace boost
 275
 276
 277 #endif //  BOOST_FORMAT_FEED_ARGS_HPP