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,
32 typename std::basic_string<Ch,Tr,Alloc>::size_type size,
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.
41 typedef typename std::basic_string<Ch,Tr,Alloc>::size_type size_type;
43 if(w<=0 || static_cast<size_type>(w) <=size) {
45 res.reserve(size + !!prefix_space);
47 res.append(1, prefix_space);
48 res.append(beg, size);
51 std::streamsize n=static_cast<std::streamsize>(w-size-!!prefix_space);
52 std::streamsize n_after = 0, n_before = 0;
53 res.reserve(w); // allocate once for the 2 inserts
55 n_after = n/2, n_before = n - n_after;
57 if(f & std::ios_base::left)
61 // now make the res string :
62 if(n_before) res.append(n_before, fill_char);
64 res.append(1, prefix_space);
65 res.append(beg, size);
66 if(n_after) res.append(n_after, fill_char);
71 #if BOOST_WORKAROUND( BOOST_MSVC, <= 1300) || \
72 BOOST_WORKAROUND(__DECCXX_VER, BOOST_TESTED_AT(60590042))
73 // MSVC needs to be tricked to disambiguate this simple overload..
74 // the trick is in "boost/format/msvc_disambiguater.hpp"
76 template< class Ch, class Tr, class T> inline
77 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
78 disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
80 template< class Ch, class Tr, class T> inline
81 void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
82 disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
87 template< class Ch, class Tr, class T> inline
88 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
91 template< class Ch, class Tr, class T> inline
92 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
93 os << group_head(x.a1_); // send the first N-1 items, not the last
96 template< class Ch, class Tr, class T> inline
97 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
101 template< class Ch, class Tr, class T> inline
102 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
103 os << group_last(x.a1_); // this selects the last element
106 #ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST
107 template< class Ch, class Tr, class T> inline
108 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
111 template< class Ch, class Tr, class T> inline
112 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
116 #endif // -msvc workaround
119 template< class Ch, class Tr, class Alloc, class T>
121 const format_item<Ch, Tr, Alloc>& specs,
122 typename basic_format<Ch, Tr, Alloc>::string_type& res,
123 typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
124 io::detail::locale_t *loc_p = NULL)
126 // does the actual conversion of x, with given params, into a string
127 // using the supplied stringbuf.
129 typedef typename basic_format<Ch, Tr, Alloc>::string_type string_type;
130 typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
131 typedef typename string_type::size_type size_type;
133 basic_oaltstringstream<Ch, Tr, Alloc> oss( &buf);
134 specs.fmtstate_.apply_on(oss, loc_p);
136 // the stream format state can be modified by manipulators in the argument :
138 // in case x is a group, apply the manip part of it,
139 // in order to find width
141 const std::ios_base::fmtflags fl=oss.flags();
142 const bool internal = (fl & std::ios_base::internal) != 0;
143 const std::streamsize w = oss.width();
144 const bool two_stepped_padding= internal && (w!=0);
147 if(! two_stepped_padding) {
148 if(w>0) // handle padding via mk_str, not natively in stream
151 const Ch * res_beg = buf.pbase();
153 if(specs.pad_scheme_ & format_item_t::spacepad)
154 if(buf.pcount()== 0 ||
155 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
156 prefix_space = oss.widen(' ');
157 size_type res_size = (std::min)(
158 static_cast<size_type>(specs.truncate_ - !!prefix_space),
160 mk_str(res, res_beg, res_size, w, oss.fill(), fl,
161 prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
163 else { // 2-stepped padding
164 // internal can be implied by zeropad, or user-set.
165 // left, right, and centered alignment overrule internal,
166 // but spacepad or truncate might be mixed with internal (using manipulator)
167 put_last( oss, x); // may pad
168 const Ch * res_beg = buf.pbase();
169 size_type res_size = buf.pcount();
170 bool prefix_space=false;
171 if(specs.pad_scheme_ & format_item_t::spacepad)
172 if(buf.pcount()== 0 ||
173 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
175 if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
176 // okay, only one thing was printed and padded, so res is fine
177 res.assign(res_beg, res_size);
179 else { // length w exceeded
180 // either it was multi-output with first output padding up all width..
181 // either it was one big arg and we are fine.
182 // Note that res_size<w is possible (in case of bad user-defined formatting)
183 res.assign(res_beg, res_size);
184 res_beg=NULL; // invalidate pointers.
186 // make a new stream, to start re-formatting from scratch :
188 basic_oaltstringstream<Ch, Tr, Alloc> oss2( &buf);
189 specs.fmtstate_.apply_on(oss2, loc_p);
196 if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
200 // we now have the minimal-length output
201 const Ch * tmp_beg = buf.pbase();
202 size_type tmp_size = (std::min)(static_cast<size_type>(specs.truncate_),
206 if(static_cast<size_type>(w) <= tmp_size) {
207 // minimal length is already >= w, so no padding (cool!)
208 res.assign(tmp_beg, tmp_size);
210 else { // hum.. we need to pad (multi_output, or spacepad present)
211 //find where we should pad
212 size_type sz = (std::min)(res_size+prefix_space, tmp_size);
213 size_type i = prefix_space;
214 for(; i<sz && tmp_beg[i] == res[i-prefix_space]; ++i) {}
215 if(i>=tmp_size) i=prefix_space;
216 res.assign(tmp_beg, i);
217 std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
219 res.append(static_cast<size_type>( d ), oss2.fill());
220 res.append(tmp_beg+i, tmp_size-i);
221 BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0)
222 == static_cast<size_type>(w));
223 BOOST_ASSERT(res.size() == static_cast<size_type>(w));
231 template< class Ch, class Tr, class Alloc, class T>
232 void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
233 // call put(x, ..) on every occurence of the current argument :
234 if(self.cur_arg_ >= self.num_args_) {
235 if( self.exceptions() & too_many_args_bit )
236 boost::throw_exception(too_many_args(self.cur_arg_, self.num_args_));
239 for(unsigned long i=0; i < self.items_.size(); ++i) {
240 if(self.items_[i].argN_ == self.cur_arg_) {
241 put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
242 self.buf_, boost::get_pointer(self.loc_) );
247 template<class Ch, class Tr, class Alloc, class T>
248 basic_format<Ch, Tr, Alloc>&
249 feed (basic_format<Ch,Tr, Alloc>& self, T x) {
250 if(self.dumped_) self.clear();
251 distribute<Ch, Tr, Alloc, T> (self, x);
253 if(self.bound_.size() != 0) {
254 while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
260 } // namespace detail
265 #endif // BOOST_FORMAT_FEED_ARGS_HPP