1 // ----------------------------------------------------------------------------
2 // feed_args.hpp : functions for processing each argument
3 // (feed, feed_manip, and distribute)
4 // ----------------------------------------------------------------------------
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)
10 // See http://www.boost.org/libs/format for library home page
12 // ----------------------------------------------------------------------------
14 #ifndef BOOST_FORMAT_FEED_ARGS_HPP
15 #define BOOST_FORMAT_FEED_ARGS_HPP
17 #include <boost/config.hpp>
18 #include <boost/assert.hpp>
19 #include <boost/throw_exception.hpp>
21 #include <boost/format/format_class.hpp>
22 #include <boost/format/group.hpp>
23 #include <boost/format/detail/msvc_disambiguater.hpp>
29 template<class Ch, class Tr, class Alloc>
30 void mk_str( std::basic_string<Ch,Tr, Alloc> & res,
35 std::ios_base::fmtflags f,
36 const Ch prefix_space, // 0 if no space-padding
38 // applies centered/left/right padding to the string [beg, beg+size[
39 // Effects : the result is placed in res.
42 std::streamsize n=w-size-!!prefix_space;
43 std::streamsize n_after = 0, n_before = 0;
45 if(n<=0) { // no need to pad.
46 res.reserve(size + !!prefix_space);
49 res.reserve(w); // allocate once for the 2 inserts
51 n_after = n/2, n_before = n - n_after;
53 if(f & std::ios_base::left)
58 // now make the res string :
59 if(n_before) res.append(n_before, fill_char);
61 res.append(1, prefix_space);
62 res.append(beg, size);
63 if(n_after) res.append(n_after, fill_char);
67 #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300)
68 // MSVC needs to be tricked to disambiguate this simple overload..
69 // the trick is in "boost/format/msvc_disambiguater.hpp"
71 template< class Ch, class Tr, class T> inline
72 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
73 disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
75 template< class Ch, class Tr, class T> inline
76 void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
77 disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
82 template< class Ch, class Tr, class T> inline
83 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
86 template< class Ch, class Tr, class T> inline
87 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
88 os << group_head(x.a1_); // send the first N-1 items, not the last
91 template< class Ch, class Tr, class T> inline
92 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
96 template< class Ch, class Tr, class T> inline
97 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
98 os << group_last(x.a1_); // this selects the last element
101 #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST
102 template< class Ch, class Tr, class T> inline
103 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
106 template< class Ch, class Tr, class T> inline
107 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
111 #endif // -msvc workaround
114 template< class Ch, class Tr, class Alloc, class T>
116 const format_item<Ch, Tr, Alloc>& specs,
117 typename basic_format<Ch, Tr, Alloc>::string_type& res,
118 typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
119 io::detail::locale_t *loc_p = NULL)
121 // does the actual conversion of x, with given params, into a string
122 // using the supplied stringbuf.
124 typedef typename basic_format<Ch, Tr, Alloc>::string_type string_type;
125 typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
126 typedef typename string_type::size_type size_type;
128 basic_oaltstringstream<Ch, Tr, Alloc> oss( &buf);
129 specs.fmtstate_.apply_on(oss, loc_p);
131 // the stream format state can be modified by manipulators in the argument :
133 // in case x is a group, apply the manip part of it,
134 // in order to find width
136 const std::ios_base::fmtflags fl=oss.flags();
137 const bool internal = (fl & std::ios_base::internal) != 0;
138 const std::streamsize w = oss.width();
139 const bool two_stepped_padding= internal && (w!=0);
142 if(! two_stepped_padding) {
143 if(w>0) // handle padding via mk_str, not natively in stream
146 const Ch * res_beg = buf.pbase();
148 if(specs.pad_scheme_ & format_item_t::spacepad)
149 if(buf.pcount()== 0 ||
150 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
151 prefix_space = oss.widen(' ');
152 std::streamsize res_size = (std::min)(
153 static_cast<std::streamsize>(specs.truncate_ - !!prefix_space),
155 mk_str(res, res_beg, res_size, w, oss.fill(), fl,
156 prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
158 else { // 2-stepped padding
159 // internal can be implied by zeropad, or user-set.
160 // left, right, and centered alignment overrule internal,
161 // but spacepad or truncate might be mixed with internal (using manipulator)
162 put_last( oss, x); // may pad
163 const Ch * res_beg = buf.pbase();
164 std::streamsize res_size = buf.pcount();
165 bool prefix_space=false;
166 if(specs.pad_scheme_ & format_item_t::spacepad)
167 if(buf.pcount()== 0 ||
168 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
170 if(res_size == w && w<=specs.truncate_ && !prefix_space) {
171 // okay, only one thing was printed and padded, so res is fine
172 res.assign(res_beg, res_size);
174 else { // length w exceeded
175 // either it was multi-output with first output padding up all width..
176 // either it was one big arg and we are fine.
177 // Note that res_size<w is possible (in case of bad user-defined formatting)
178 res.assign(res_beg, res_size);
179 res_beg=NULL; // invalidate pointers.
181 // make a new stream, to start re-formatting from scratch :
183 basic_oaltstringstream<Ch, Tr, Alloc> oss2( &buf);
184 specs.fmtstate_.apply_on(oss2, loc_p);
191 if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
195 // we now have the minimal-length output
196 const Ch * tmp_beg = buf.pbase();
197 std::streamsize tmp_size = (std::min)(static_cast<std::streamsize>(specs.truncate_),
201 if( (d=w - tmp_size) <=0 ) {
202 // minimal length is already >= w, so no padding (cool!)
203 res.assign(tmp_beg, tmp_size);
205 else { // hum.. we need to pad (multi_output, or spacepad present)
206 std::streamsize i = prefix_space;
207 //find where we should pad
208 std::streamsize sz = (std::min)(res_size+prefix_space, tmp_size);
209 for(; i<sz && tmp_beg[i] == res[i-prefix_space]; ++i) {}
210 if(i>=tmp_size) i=prefix_space;
211 res.assign(tmp_beg, i);
212 if(d>0) res.append(static_cast<size_type>( d ), oss2.fill());
213 res.append(tmp_beg+i, tmp_size-i);
214 BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0) == w);
215 BOOST_ASSERT(res.size() == (std::size_t)w);
223 template< class Ch, class Tr, class Alloc, class T>
224 void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
225 // call put(x, ..) on every occurence of the current argument :
226 if(self.cur_arg_ >= self.num_args_) {
227 if( self.exceptions() & too_many_args_bit )
228 boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_));
231 for(unsigned long i=0; i < self.items_.size(); ++i) {
232 if(self.items_[i].argN_ == self.cur_arg_) {
233 put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
234 self.buf_, boost::get_pointer(self.loc_) );
239 template<class Ch, class Tr, class Alloc, class T>
240 basic_format<Ch, Tr, Alloc>&
241 feed (basic_format<Ch,Tr, Alloc>& self, T x) {
242 if(self.dumped_) self.clear();
243 distribute<Ch, Tr, Alloc, T> (self, x);
245 if(self.bound_.size() != 0) {
246 while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
252 } // namespace detail
257 #endif // BOOST_FORMAT_FEED_ARGS_HPP