feed_args.hpp 11 KB

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  1. // ----------------------------------------------------------------------------
  2. // feed_args.hpp : functions for processing each argument
  3. // (feed, feed_manip, and distribute)
  4. // ----------------------------------------------------------------------------
  5. // Copyright Samuel Krempp 2003. Use, modification, and distribution are
  6. // subject to the Boost Software License, Version 1.0. (See accompanying
  7. // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  8. // See http://www.boost.org/libs/format for library home page
  9. // ----------------------------------------------------------------------------
  10. #ifndef BOOST_FORMAT_FEED_ARGS_HPP
  11. #define BOOST_FORMAT_FEED_ARGS_HPP
  12. #include <boost/config.hpp>
  13. #include <boost/assert.hpp>
  14. #include <boost/throw_exception.hpp>
  15. #include <boost/format/format_class.hpp>
  16. #include <boost/format/group.hpp>
  17. #include <boost/format/detail/msvc_disambiguater.hpp>
  18. namespace boost {
  19. namespace io {
  20. namespace detail {
  21. template<class Ch, class Tr, class Alloc>
  22. void mk_str( std::basic_string<Ch,Tr, Alloc> & res,
  23. const Ch * beg,
  24. typename std::basic_string<Ch,Tr,Alloc>::size_type size,
  25. std::streamsize w,
  26. const Ch fill_char,
  27. std::ios_base::fmtflags f,
  28. const Ch prefix_space, // 0 if no space-padding
  29. bool center)
  30. // applies centered/left/right padding to the string [beg, beg+size[
  31. // Effects : the result is placed in res.
  32. {
  33. typedef typename std::basic_string<Ch,Tr,Alloc>::size_type size_type;
  34. res.resize(0);
  35. if(w<=0 || static_cast<size_type>(w) <=size) {
  36. // no need to pad.
  37. res.reserve(size + !!prefix_space);
  38. if(prefix_space)
  39. res.append(1, prefix_space);
  40. if (size)
  41. res.append(beg, size);
  42. }
  43. else {
  44. std::streamsize n=static_cast<std::streamsize>(w-size-!!prefix_space);
  45. std::streamsize n_after = 0, n_before = 0;
  46. res.reserve(static_cast<size_type>(w)); // allocate once for the 2 inserts
  47. if(center)
  48. n_after = n/2, n_before = n - n_after;
  49. else
  50. if(f & std::ios_base::left)
  51. n_after = n;
  52. else
  53. n_before = n;
  54. // now make the res string :
  55. if(n_before) res.append(static_cast<size_type>(n_before), fill_char);
  56. if(prefix_space)
  57. res.append(1, prefix_space);
  58. if (size)
  59. res.append(beg, size);
  60. if(n_after) res.append(static_cast<size_type>(n_after), fill_char);
  61. }
  62. } // -mk_str(..)
  63. #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300) || \
  64. BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
  65. // MSVC needs to be tricked to disambiguate this simple overload..
  66. // the trick is in "boost/format/msvc_disambiguater.hpp"
  67. template< class Ch, class Tr, class T> inline
  68. void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
  69. disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
  70. }
  71. template< class Ch, class Tr, class T> inline
  72. void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
  73. disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
  74. }
  75. #else
  76. template< class Ch, class Tr, class T> inline
  77. void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
  78. }
  79. template< class Ch, class Tr, class T> inline
  80. void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
  81. os << group_head(x.a1_); // send the first N-1 items, not the last
  82. }
  83. template< class Ch, class Tr, class T> inline
  84. void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
  85. os << x ;
  86. }
  87. template< class Ch, class Tr, class T> inline
  88. void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
  89. os << group_last(x.a1_); // this selects the last element
  90. }
  91. #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST
  92. template< class Ch, class Tr, class T> inline
  93. void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
  94. }
  95. template< class Ch, class Tr, class T> inline
  96. void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
  97. os << x ;
  98. }
  99. #endif
  100. #endif // -msvc workaround
  101. template< class Ch, class Tr, class Alloc, class T>
  102. void put( T x,
  103. const format_item<Ch, Tr, Alloc>& specs,
  104. typename basic_format<Ch, Tr, Alloc>::string_type& res,
  105. typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
  106. io::detail::locale_t *loc_p = NULL)
  107. {
  108. #ifdef BOOST_MSVC
  109. // If std::min<unsigned> or std::max<unsigned> are already instantiated
  110. // at this point then we get a blizzard of warning messages when we call
  111. // those templates with std::size_t as arguments. Weird and very annoyning...
  112. #pragma warning(push)
  113. #pragma warning(disable:4267)
  114. #endif
  115. // does the actual conversion of x, with given params, into a string
  116. // using the supplied stringbuf.
  117. typedef typename basic_format<Ch, Tr, Alloc>::string_type string_type;
  118. typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
  119. typedef typename string_type::size_type size_type;
  120. basic_oaltstringstream<Ch, Tr, Alloc> oss( &buf);
  121. specs.fmtstate_.apply_on(oss, loc_p);
  122. // the stream format state can be modified by manipulators in the argument :
  123. put_head( oss, x );
  124. // in case x is a group, apply the manip part of it,
  125. // in order to find width
  126. const std::ios_base::fmtflags fl=oss.flags();
  127. const bool internal = (fl & std::ios_base::internal) != 0;
  128. const std::streamsize w = oss.width();
  129. const bool two_stepped_padding= internal && (w!=0);
  130. res.resize(0);
  131. if(! two_stepped_padding) {
  132. if(w>0) // handle padding via mk_str, not natively in stream
  133. oss.width(0);
  134. put_last( oss, x);
  135. const Ch * res_beg = buf.pbase();
  136. Ch prefix_space = 0;
  137. if(specs.pad_scheme_ & format_item_t::spacepad)
  138. if(buf.pcount()== 0 ||
  139. (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
  140. prefix_space = oss.widen(' ');
  141. size_type res_size = (std::min)(
  142. static_cast<size_type>(specs.truncate_ - !!prefix_space),
  143. buf.pcount() );
  144. mk_str(res, res_beg, res_size, w, oss.fill(), fl,
  145. prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
  146. }
  147. else { // 2-stepped padding
  148. // internal can be implied by zeropad, or user-set.
  149. // left, right, and centered alignment overrule internal,
  150. // but spacepad or truncate might be mixed with internal (using manipulator)
  151. put_last( oss, x); // may pad
  152. const Ch * res_beg = buf.pbase();
  153. size_type res_size = buf.pcount();
  154. bool prefix_space=false;
  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 = true;
  159. if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
  160. // okay, only one thing was printed and padded, so res is fine
  161. res.assign(res_beg, res_size);
  162. }
  163. else { // length w exceeded
  164. // either it was multi-output with first output padding up all width..
  165. // either it was one big arg and we are fine.
  166. // Note that res_size<w is possible (in case of bad user-defined formatting)
  167. res.assign(res_beg, res_size);
  168. res_beg=NULL; // invalidate pointers.
  169. // make a new stream, to start re-formatting from scratch :
  170. buf.clear_buffer();
  171. basic_oaltstringstream<Ch, Tr, Alloc> oss2( &buf);
  172. specs.fmtstate_.apply_on(oss2, loc_p);
  173. put_head( oss2, x );
  174. oss2.width(0);
  175. if(prefix_space)
  176. oss2 << ' ';
  177. put_last(oss2, x );
  178. if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
  179. prefix_space =true;
  180. oss2 << ' ';
  181. }
  182. // we now have the minimal-length output
  183. const Ch * tmp_beg = buf.pbase();
  184. size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_),
  185. buf.pcount() );
  186. if(static_cast<size_type>(w) <= tmp_size) {
  187. // minimal length is already >= w, so no padding (cool!)
  188. res.assign(tmp_beg, tmp_size);
  189. }
  190. else { // hum.. we need to pad (multi_output, or spacepad present)
  191. //find where we should pad
  192. size_type sz = (std::min)(res_size + (prefix_space ? 1 : 0), tmp_size);
  193. size_type i = prefix_space;
  194. for(; i<sz && tmp_beg[i] == res[i - (prefix_space ? 1 : 0)]; ++i) {}
  195. if(i>=tmp_size) i=prefix_space;
  196. res.assign(tmp_beg, i);
  197. std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
  198. BOOST_ASSERT(d>0);
  199. res.append(static_cast<size_type>( d ), oss2.fill());
  200. res.append(tmp_beg+i, tmp_size-i);
  201. BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0)
  202. == static_cast<size_type>(w));
  203. BOOST_ASSERT(res.size() == static_cast<size_type>(w));
  204. }
  205. }
  206. }
  207. buf.clear_buffer();
  208. #ifdef BOOST_MSVC
  209. #pragma warning(pop)
  210. #endif
  211. } // end- put(..)
  212. template< class Ch, class Tr, class Alloc, class T>
  213. void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
  214. // call put(x, ..) on every occurence of the current argument :
  215. if(self.cur_arg_ >= self.num_args_) {
  216. if( self.exceptions() & too_many_args_bit )
  217. boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_));
  218. else return;
  219. }
  220. for(unsigned long i=0; i < self.items_.size(); ++i) {
  221. if(self.items_[i].argN_ == self.cur_arg_) {
  222. put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
  223. self.buf_, boost::get_pointer(self.loc_) );
  224. }
  225. }
  226. }
  227. template<class Ch, class Tr, class Alloc, class T>
  228. basic_format<Ch, Tr, Alloc>&
  229. feed (basic_format<Ch,Tr, Alloc>& self, T x) {
  230. if(self.dumped_) self.clear();
  231. distribute<Ch, Tr, Alloc, T> (self, x);
  232. ++self.cur_arg_;
  233. if(self.bound_.size() != 0) {
  234. while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
  235. ++self.cur_arg_;
  236. }
  237. return self;
  238. }
  239. } // namespace detail
  240. } // namespace io
  241. } // namespace boost
  242. #endif // BOOST_FORMAT_FEED_ARGS_HPP