boost/format/feed_args.hpp
// ---------------------------------------------------------------------------- // feed_args.hpp : functions for processing each argument // (feed, feed_manip, and distribute) // ---------------------------------------------------------------------------- // Copyright Samuel Krempp 2003. Use, modification, and distribution are // subject to the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // See http://www.boost.org/libs/format for library home page // ---------------------------------------------------------------------------- #ifndef BOOST_FORMAT_FEED_ARGS_HPP #define BOOST_FORMAT_FEED_ARGS_HPP #include <boost/config.hpp> #include <boost/assert.hpp> #include <boost/throw_exception.hpp> #include <boost/format/format_class.hpp> #include <boost/format/group.hpp> #include <boost/format/detail/msvc_disambiguater.hpp> namespace boost { namespace io { namespace detail { template<class Ch, class Tr, class Alloc> void mk_str( std::basic_string<Ch,Tr, Alloc> & res, const Ch * beg, typename std::basic_string<Ch,Tr,Alloc>::size_type size, std::streamsize w, const Ch fill_char, std::ios_base::fmtflags f, const Ch prefix_space, // 0 if no space-padding bool center) // applies centered/left/right padding to the string [beg, beg+size[ // Effects : the result is placed in res. { typedef typename std::basic_string<Ch,Tr,Alloc>::size_type size_type; res.resize(0); if(w<=0 || static_cast<size_type>(w) <=size) { // no need to pad. res.reserve(size + !!prefix_space); if(prefix_space) res.append(1, prefix_space); res.append(beg, size); } else { std::streamsize n=static_cast<std::streamsize>(w-size-!!prefix_space); std::streamsize n_after = 0, n_before = 0; res.reserve(w); // allocate once for the 2 inserts if(center) n_after = n/2, n_before = n - n_after; else if(f & std::ios_base::left) n_after = n; else n_before = n; // now make the res string : if(n_before) res.append(n_before, fill_char); if(prefix_space) res.append(1, prefix_space); res.append(beg, size); if(n_after) res.append(n_after, fill_char); } } // -mk_str(..) #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300) || \ BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042)) // MSVC needs to be tricked to disambiguate this simple overload.. // the trick is in "boost/format/msvc_disambiguater.hpp" template< class Ch, class Tr, class T> inline void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) { disambiguater<Ch, Tr, T>::put_head(os, x, 1L); } template< class Ch, class Tr, class T> inline void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) { disambiguater<Ch, Tr, T>::put_last(os, x, 1L); } #else template< class Ch, class Tr, class T> inline void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) { } template< class Ch, class Tr, class T> inline void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) { os << group_head(x.a1_); // send the first N-1 items, not the last } template< class Ch, class Tr, class T> inline void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) { os << x ; } template< class Ch, class Tr, class T> inline void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) { os << group_last(x.a1_); // this selects the last element } #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST template< class Ch, class Tr, class T> inline void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) { } template< class Ch, class Tr, class T> inline void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) { os << x ; } #endif #endif // -msvc workaround template< class Ch, class Tr, class Alloc, class T> void put( T x, const format_item<Ch, Tr, Alloc>& specs, typename basic_format<Ch, Tr, Alloc>::string_type& res, typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf, io::detail::locale_t *loc_p = NULL) { // does the actual conversion of x, with given params, into a string // using the supplied stringbuf. typedef typename basic_format<Ch, Tr, Alloc>::string_type string_type; typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t; typedef typename string_type::size_type size_type; basic_oaltstringstream<Ch, Tr, Alloc> oss( &buf); specs.fmtstate_.apply_on(oss, loc_p); // the stream format state can be modified by manipulators in the argument : put_head( oss, x ); // in case x is a group, apply the manip part of it, // in order to find width const std::ios_base::fmtflags fl=oss.flags(); const bool internal = (fl & std::ios_base::internal) != 0; const std::streamsize w = oss.width(); const bool two_stepped_padding= internal && (w!=0); res.resize(0); if(! two_stepped_padding) { if(w>0) // handle padding via mk_str, not natively in stream oss.width(0); put_last( oss, x); const Ch * res_beg = buf.pbase(); Ch prefix_space = 0; if(specs.pad_scheme_ & format_item_t::spacepad) if(buf.pcount()== 0 || (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') )) prefix_space = oss.widen(' '); size_type res_size = (std::min)( static_cast<size_type>(specs.truncate_ - !!prefix_space), buf.pcount() ); mk_str(res, res_beg, res_size, w, oss.fill(), fl, prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 ); } else { // 2-stepped padding // internal can be implied by zeropad, or user-set. // left, right, and centered alignment overrule internal, // but spacepad or truncate might be mixed with internal (using manipulator) put_last( oss, x); // may pad const Ch * res_beg = buf.pbase(); size_type res_size = buf.pcount(); bool prefix_space=false; if(specs.pad_scheme_ & format_item_t::spacepad) if(buf.pcount()== 0 || (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') )) prefix_space = true; if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) { // okay, only one thing was printed and padded, so res is fine res.assign(res_beg, res_size); } else { // 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. // Note that res_size<w is possible (in case of bad user-defined formatting) res.assign(res_beg, res_size); res_beg=NULL; // invalidate pointers. // make a new stream, to start re-formatting from scratch : buf.clear_buffer(); basic_oaltstringstream<Ch, Tr, Alloc> oss2( &buf); specs.fmtstate_.apply_on(oss2, loc_p); put_head( oss2, x ); oss2.width(0); if(prefix_space) oss2 << ' '; put_last(oss2, x ); if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) { prefix_space =true; oss2 << ' '; } // we now have the minimal-length output const Ch * tmp_beg = buf.pbase(); size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_), buf.pcount() ); if(static_cast<size_type>(w) <= tmp_size) { // minimal length is already >= w, so no padding (cool!) res.assign(tmp_beg, tmp_size); } else { // hum.. we need to pad (multi_output, or spacepad present) //find where we should pad size_type sz = (std::min)(res_size+prefix_space, tmp_size); size_type i = prefix_space; for(; i<sz && tmp_beg[i] == res[i-prefix_space]; ++i) {} if(i>=tmp_size) i=prefix_space; res.assign(tmp_beg, i); std::streamsize d = w - static_cast<std::streamsize>(tmp_size); BOOST_ASSERT(d>0); res.append(static_cast<size_type>( d ), oss2.fill()); res.append(tmp_beg+i, tmp_size-i); BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0) == static_cast<size_type>(w)); BOOST_ASSERT(res.size() == static_cast<size_type>(w)); } } } buf.clear_buffer(); } // end- put(..) template< class Ch, class Tr, class Alloc, class T> void distribute (basic_format<Ch,Tr, Alloc>& 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(self.cur_arg_, self.num_args_)); else return; } for(unsigned long i=0; i < self.items_.size(); ++i) { if(self.items_[i].argN_ == self.cur_arg_) { put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_, self.buf_, boost::get_pointer(self.loc_) ); } } } template<class Ch, class Tr, class Alloc, class T> basic_format<Ch, Tr, Alloc>& feed (basic_format<Ch,Tr, Alloc>& self, T x) { if(self.dumped_) self.clear(); distribute<Ch, Tr, Alloc, 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_; } return self; } } // namespace detail } // namespace io } // namespace boost #endif // BOOST_FORMAT_FEED_ARGS_HPP