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
25namespace boost {
26namespace io {
27namespace 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(__DECCXX_VER, BOOST_TESTED_AT(60590042))
74// __DECCXX needs to be tricked to disambiguate this simple overload..
75// the trick is in "boost/format/msvc_disambiguater.hpp"
76
77 template< class Ch, class Tr, class T> inline
78 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
79 disambiguater<Ch, Tr, T>::put_head(os, x, 1L);
80 }
81 template< class Ch, class Tr, class T> inline
82 void put_last (BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
83 disambiguater<Ch, Tr, T>::put_last(os, x, 1L);
84 }
85
86#else
87
88 template< class Ch, class Tr, class T> inline
89 void put_head (BOOST_IO_STD basic_ostream<Ch, Tr> &, const T& ) {
90 }
91
92 template< class Ch, class Tr, class T> inline
93 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
94 os << group_head(x.a1_); // send the first N-1 items, not the last
95 }
96
97 template< class Ch, class Tr, class T> inline
98 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const T& x ) {
99 os << x ;
100 }
101
102 template< class Ch, class Tr, class T> inline
103 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const group1<T>& x ) {
104 os << group_last(x.a1_); // this selects the last element
105 }
106
107#ifndef BOOST_NO_OVERLOAD_FOR_NON_CONST
108 template< class Ch, class Tr, class T> inline
109 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> &, T& ) {
110 }
111
112 template< class Ch, class Tr, class T> inline
113 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, T& x) {
114 os << x ;
115 }
116#endif
117#endif // -__DECCXX workaround
118
119 template< class Ch, class Tr, class T>
120 void call_put_head(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x) {
121 put_head(os, *(static_cast<T const *>(x)));
122 }
123
124 template< class Ch, class Tr, class T>
125 void call_put_last(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x) {
126 put_last(os, *(static_cast<T const *>(x)));
127 }
128
129 template< class Ch, class Tr>
130 struct put_holder {
131 template<class T>
132 put_holder(T& t)
133 : arg(&t),
134 put_head(&call_put_head<Ch, Tr, T>),
135 put_last(&call_put_last<Ch, Tr, T>)
136 {}
137 const void* arg;
138 void (*put_head)(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x);
139 void (*put_last)(BOOST_IO_STD basic_ostream<Ch, Tr> & os, const void* x);
140 };
141
142 template< class Ch, class Tr> inline
143 void put_head( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const put_holder<Ch, Tr>& t) {
144 t.put_head(os, t.arg);
145 }
146
147 template< class Ch, class Tr> inline
148 void put_last( BOOST_IO_STD basic_ostream<Ch, Tr> & os, const put_holder<Ch, Tr>& t) {
149 t.put_last(os, t.arg);
150 }
151
152
153 template< class Ch, class Tr, class Alloc, class T>
154 void put( T x,
155 const format_item<Ch, Tr, Alloc>& specs,
156 typename basic_format<Ch, Tr, Alloc>::string_type& res,
157 typename basic_format<Ch, Tr, Alloc>::internal_streambuf_t & buf,
158 io::detail::locale_t *loc_p = NULL)
159 {
160#ifdef BOOST_MSVC
161 // If std::min<unsigned> or std::max<unsigned> are already instantiated
162 // at this point then we get a blizzard of warning messages when we call
163 // those templates with std::size_t as arguments. Weird and very annoyning...
164#pragma warning(push)
165#pragma warning(disable:4267)
166#endif
167 // does the actual conversion of x, with given params, into a string
168 // using the supplied stringbuf.
169
170 typedef typename basic_format<Ch, Tr, Alloc>::string_type string_type;
171 typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
172 typedef typename string_type::size_type size_type;
173
174 basic_oaltstringstream<Ch, Tr, Alloc> oss( &buf);
175
176#if !defined(BOOST_NO_STD_LOCALE)
177 if(loc_p != NULL)
178 oss.imbue(*loc_p);
179#endif
180
181 specs.fmtstate_.apply_on(oss, loc_p);
182
183 // the stream format state can be modified by manipulators in the argument :
184 put_head( oss, x );
185 // in case x is a group, apply the manip part of it,
186 // in order to find width
187
188 const std::ios_base::fmtflags fl=oss.flags();
189 const bool internal = (fl & std::ios_base::internal) != 0;
190 const std::streamsize w = oss.width();
191 const bool two_stepped_padding= internal && (w!=0);
192
193 res.resize(0);
194 if(! two_stepped_padding) {
195 if(w>0) // handle padding via mk_str, not natively in stream
196 oss.width(0);
197 put_last( oss, x);
198 const Ch * res_beg = buf.pbase();
199 Ch prefix_space = 0;
200 if(specs.pad_scheme_ & format_item_t::spacepad)
201 if(buf.pcount()== 0 ||
202 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
203 prefix_space = oss.widen(' ');
204 size_type res_size = (std::min)(
205 (static_cast<size_type>((specs.truncate_ & (std::numeric_limits<size_type>::max)())) - !!prefix_space),
206 buf.pcount() );
207 mk_str(res, res_beg, res_size, w, oss.fill(), fl,
208 prefix_space, (specs.pad_scheme_ & format_item_t::centered) !=0 );
209 }
210 else { // 2-stepped padding
211 // internal can be implied by zeropad, or user-set.
212 // left, right, and centered alignment overrule internal,
213 // but spacepad or truncate might be mixed with internal (using manipulator)
214 put_last( oss, x); // may pad
215 const Ch * res_beg = buf.pbase();
216 size_type res_size = buf.pcount();
217 bool prefix_space=false;
218 if(specs.pad_scheme_ & format_item_t::spacepad)
219 if(buf.pcount()== 0 ||
220 (res_beg[0] !=oss.widen('+') && res_beg[0] !=oss.widen('-') ))
221 prefix_space = true;
222 if(res_size == static_cast<size_type>(w) && w<=specs.truncate_ && !prefix_space) {
223 // okay, only one thing was printed and padded, so res is fine
224 res.assign(res_beg, res_size);
225 }
226 else { // length w exceeded
227 // either it was multi-output with first output padding up all width..
228 // either it was one big arg and we are fine.
229 // Note that res_size<w is possible (in case of bad user-defined formatting)
230 res.assign(res_beg, res_size);
231 res_beg=NULL; // invalidate pointers.
232
233 // make a new stream, to start re-formatting from scratch :
234 buf.clear_buffer();
235 basic_oaltstringstream<Ch, Tr, Alloc> oss2( &buf);
236 specs.fmtstate_.apply_on(oss2, loc_p);
237 put_head( oss2, x );
238
239 oss2.width(0);
240 if(prefix_space)
241 oss2 << ' ';
242 put_last(oss2, x );
243 if(buf.pcount()==0 && specs.pad_scheme_ & format_item_t::spacepad) {
244 prefix_space =true;
245 oss2 << ' ';
246 }
247 // we now have the minimal-length output
248 const Ch * tmp_beg = buf.pbase();
249 size_type tmp_size = (std::min)(
250 (static_cast<size_type>(specs.truncate_ & (std::numeric_limits<size_type>::max)())),
251 buf.pcount());
252
253 if(static_cast<size_type>(w) <= tmp_size) {
254 // minimal length is already >= w, so no padding (cool!)
255 res.assign(tmp_beg, tmp_size);
256 }
257 else { // hum.. we need to pad (multi_output, or spacepad present)
258 //find where we should pad
259 size_type sz = (std::min)(res_size + (prefix_space ? 1 : 0), tmp_size);
260 size_type i = prefix_space;
261 for(; i<sz && tmp_beg[i] == res[i - (prefix_space ? 1 : 0)]; ++i) {}
262 if(i>=tmp_size) i=prefix_space;
263 res.assign(tmp_beg, i);
264 std::streamsize d = w - static_cast<std::streamsize>(tmp_size);
265 BOOST_ASSERT(d>0);
266 res.append(static_cast<size_type>( d ), oss2.fill());
267 res.append(tmp_beg+i, tmp_size-i);
268 BOOST_ASSERT(i+(tmp_size-i)+(std::max)(d,(std::streamsize)0)
269 == static_cast<size_type>(w));
270 BOOST_ASSERT(res.size() == static_cast<size_type>(w));
271 }
272 }
273 }
274 buf.clear_buffer();
275#ifdef BOOST_MSVC
276#pragma warning(pop)
277#endif
278 } // end- put(..)
279
280
281 template< class Ch, class Tr, class Alloc, class T>
282 void distribute (basic_format<Ch,Tr, Alloc>& self, T x) {
283 // call put(x, ..) on every occurrence of the current argument :
284 if(self.cur_arg_ >= self.num_args_) {
285 if( self.exceptions() & too_many_args_bit )
286 boost::throw_exception(e: too_many_args(self.cur_arg_, self.num_args_));
287 else return;
288 }
289 for(unsigned long i=0; i < self.items_.size(); ++i) {
290 if(self.items_[i].argN_ == self.cur_arg_) {
291 put<Ch, Tr, Alloc, T> (x, self.items_[i], self.items_[i].res_,
292 self.buf_, boost::get_pointer(self.loc_) );
293 }
294 }
295 }
296
297 template<class Ch, class Tr, class Alloc, class T>
298 basic_format<Ch, Tr, Alloc>&
299 feed_impl (basic_format<Ch,Tr, Alloc>& self, T x) {
300 if(self.dumped_) self.clear();
301 distribute<Ch, Tr, Alloc, T> (self, x);
302 ++self.cur_arg_;
303 if(self.bound_.size() != 0) {
304 while( self.cur_arg_ < self.num_args_ && self.bound_[self.cur_arg_] )
305 ++self.cur_arg_;
306 }
307 return self;
308 }
309
310 template<class Ch, class Tr, class Alloc, class T> inline
311 basic_format<Ch, Tr, Alloc>&
312 feed (basic_format<Ch,Tr, Alloc>& self, T x) {
313 return feed_impl<Ch, Tr, Alloc, const put_holder<Ch, Tr>&>(self, put_holder<Ch, Tr>(x));
314 }
315
316} // namespace detail
317} // namespace io
318} // namespace boost
319
320
321#endif // BOOST_FORMAT_FEED_ARGS_HPP
322

source code of include/boost/format/feed_args.hpp