1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2 // (C) Copyright 2003-2007 Jonathan Turkanis
3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
5
6 // See http://www.boost.org/libs/iostreams for documentation.
7
8 //
9 // Contains metafunctions char_type_of, category_of and mode_of used for
10 // deducing the i/o category and i/o mode of a model of Filter or Device.
11 //
12 // Also contains several utility metafunctions, functions and macros.
13 //
14
15 #ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED
16 #define BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED
17
18 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
19 # pragma once
20 #endif
21
22 #include <iosfwd> // stream types, char_traits.
23 #include <boost/config.hpp> // partial spec, deduced typename.
24 #include <boost/detail/workaround.hpp>
25 #include <boost/iostreams/categories.hpp>
26 #include <boost/iostreams/detail/bool_trait_def.hpp>
27 #include <boost/iostreams/detail/config/wide_streams.hpp>
28 #include <boost/iostreams/detail/is_iterator_range.hpp>
29 #include <boost/iostreams/detail/select.hpp>
30 #include <boost/iostreams/detail/select_by_size.hpp>
31 #include <boost/iostreams/detail/wrap_unwrap.hpp>
32 #include <boost/iostreams/traits_fwd.hpp>
33 #include <boost/mpl/bool.hpp>
34 #include <boost/mpl/eval_if.hpp>
35 #include <boost/mpl/identity.hpp>
36 #include <boost/mpl/int.hpp>
37 #include <boost/mpl/or.hpp>
38 #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
39 # include <boost/range/iterator_range.hpp>
40 # include <boost/range/value_type.hpp>
41 #endif // #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
42 #include <boost/ref.hpp>
43 #include <boost/type_traits/is_convertible.hpp>
44
45 // Must come last.
46 #include <boost/iostreams/detail/config/disable_warnings.hpp>
47
48 namespace boost { namespace iostreams {
49
50 //----------Definitions of predicates for streams and stream buffers----------//
51
52 #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------------------//
53
54 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::basic_istream, 2)
55 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::basic_ostream, 2)
56 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::basic_iostream, 2)
57 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::basic_streambuf, 2)
58 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ifstream, std::basic_ifstream, 2)
59 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ofstream, std::basic_ofstream, 2)
60 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_fstream, std::basic_fstream, 2)
61 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_filebuf, std::basic_filebuf, 2)
62 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istringstream, std::basic_istringstream, 3)
63 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostringstream, std::basic_ostringstream, 3)
64 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringstream, std::basic_stringstream, 3)
65 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringbuf, std::basic_stringbuf, 3)
66
67 #else // #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-----------------------//
68
69 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::istream, 0)
70 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::ostream, 0)
71 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::iostream, 0)
72 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::streambuf, 0)
73
74 #endif // #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //----------------------//
75
76 template<typename T>
77 struct is_std_io
78 : mpl::or_< is_istream<T>, is_ostream<T>, is_streambuf<T> >
79 { };
80
81 template<typename T>
82 struct is_std_file_device
83 : mpl::or_<
84 is_ifstream<T>,
85 is_ofstream<T>,
86 is_fstream<T>,
87 is_filebuf<T>
88 >
89 { };
90
91 template<typename T>
92 struct is_std_string_device
93 : mpl::or_<
94 is_istringstream<T>,
95 is_ostringstream<T>,
96 is_stringstream<T>,
97 is_stringbuf<T>
98 >
99 { };
100
101 template<typename Device, typename Tr, typename Alloc>
102 struct stream;
103
104 template<typename T, typename Tr, typename Alloc, typename Mode>
105 class stream_buffer;
106
107 template< typename Mode, typename Ch, typename Tr,
108 typename Alloc, typename Access >
109 class filtering_stream;
110
111 template< typename Mode, typename Ch, typename Tr,
112 typename Alloc, typename Access >
113 class wfiltering_stream;
114
115 template< typename Mode, typename Ch, typename Tr,
116 typename Alloc, typename Access >
117 class filtering_streambuf;
118
119 template< typename Mode, typename Ch, typename Tr,
120 typename Alloc, typename Access >
121 class filtering_wstreambuf;
122
123 namespace detail {
124
125 template<typename T, typename Tr>
126 class linked_streambuf;
127
128 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_boost_stream,
129 boost::iostreams::stream,
130 3 )
131 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_boost_stream_buffer,
132 boost::iostreams::stream_buffer,
133 4 )
134 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_stream_impl,
135 boost::iostreams::filtering_stream,
136 5 )
137 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_wstream_impl,
138 boost::iostreams::wfiltering_stream,
139 5 )
140 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_streambuf_impl,
141 boost::iostreams::filtering_streambuf,
142 5 )
143 BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_wstreambuf_impl,
144 boost::iostreams::filtering_wstreambuf,
145 5 )
146 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_linked, linked_streambuf, 2)
147
148 template<typename T>
149 struct is_filtering_stream
150 : mpl::or_<
151 is_filtering_stream_impl<T>,
152 is_filtering_wstream_impl<T>
153 >
154 { };
155
156 template<typename T>
157 struct is_filtering_streambuf
158 : mpl::or_<
159 is_filtering_streambuf_impl<T>,
160 is_filtering_wstreambuf_impl<T>
161 >
162 { };
163
164 template<typename T>
165 struct is_boost
166 : mpl::or_<
167 is_boost_stream<T>,
168 is_boost_stream_buffer<T>,
169 is_filtering_stream<T>,
170 is_filtering_streambuf<T>
171 >
172 { };
173
174 } // End namespace detail.
175
176 //------------------Definitions of char_type_of-------------------------------//
177
178 namespace detail {
179
180 template<typename T>
181 struct member_char_type { typedef typename T::char_type type; };
182
183 } // End namespace detail.
184
185 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //---------------------------//
186 # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-------------------------------//
187
188 template<typename T>
189 struct char_type_of
190 : detail::member_char_type<
191 typename detail::unwrapped_type<T>::type
192 >
193 { };
194
195 # else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //---------------------//
196
197 template<typename T>
198 struct char_type_of {
199 typedef typename detail::unwrapped_type<T>::type U;
200 typedef typename
201 mpl::eval_if<
202 is_std_io<U>,
203 mpl::identity<char>,
204 detail::member_char_type<U>
205 >::type type;
206 };
207
208 # endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------//
209
210 template<typename Iter>
211 struct char_type_of< iterator_range<Iter> > {
212 typedef typename iterator_value<Iter>::type type;
213 };
214
215 #else // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //------------------//
216
217 template<typename T>
218 struct char_type_of {
219 template<typename U>
220 struct get_value_type {
221 #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
222 typedef typename range_value<U>::type type;
223 #endif // #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
224 };
225 typedef typename
226 mpl::eval_if<
227 is_iterator_range<T>,
228 get_value_type<T>,
229 detail::member_char_type<
230 BOOST_DEDUCED_TYPENAME detail::unwrapped_type<T>::type
231 >
232 >::type type;
233 };
234
235 #endif // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //-----------------//
236
237 //------------------Definitions of category_of--------------------------------//
238
239 namespace detail {
240
241 template<typename T>
242 struct member_category { typedef typename T::category type; };
243
244 } // End namespace detail.
245
246 template<typename T>
247 struct category_of {
248 template<typename U>
249 struct member_category {
250 typedef typename U::category type;
251 };
252 typedef typename detail::unwrapped_type<T>::type U;
253 typedef typename
254 mpl::eval_if<
255 mpl::and_<
256 is_std_io<U>,
257 mpl::not_< detail::is_boost<U> >
258 >,
259 iostreams::select< // Disambiguation for Tru64
260 is_filebuf<U>, filebuf_tag,
261 is_ifstream<U>, ifstream_tag,
262 is_ofstream<U>, ofstream_tag,
263 is_fstream<U>, fstream_tag,
264 is_stringbuf<U>, stringbuf_tag,
265 is_istringstream<U>, istringstream_tag,
266 is_ostringstream<U>, ostringstream_tag,
267 is_stringstream<U>, stringstream_tag,
268 is_streambuf<U>, generic_streambuf_tag,
269 is_iostream<U>, generic_iostream_tag,
270 is_istream<U>, generic_istream_tag,
271 is_ostream<U>, generic_ostream_tag
272 >,
273 detail::member_category<U>
274 >::type type;
275 };
276
277 // Partial specialization for reference wrappers
278 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //---------------------------//
279
280 template<typename T>
281 struct category_of< reference_wrapper<T> >
282 : category_of<T>
283 { };
284
285 #endif // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //-----------------//
286
287 //------------------Definition of get_category--------------------------------//
288
289 //
290 // Returns an object of type category_of<T>::type.
291 //
292 template<typename T>
get_category(const T &)293 inline typename category_of<T>::type get_category(const T&)
294 { typedef typename category_of<T>::type category; return category(); }
295
296 //------------------Definition of int_type_of---------------------------------//
297
298 template<typename T>
299 struct int_type_of {
300 #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES
301 typedef std::char_traits<
302 BOOST_DEDUCED_TYPENAME char_type_of<T>::type
303 > traits_type;
304 typedef typename traits_type::int_type type;
305 #else
306 typedef int type;
307 #endif
308 };
309
310 //------------------Definition of mode_of-------------------------------------//
311
312 namespace detail {
313
314 template<int N> struct io_mode_impl;
315
316 #define BOOST_IOSTREAMS_MODE_HELPER(tag_, id_) \
317 case_<id_> io_mode_impl_helper(tag_); \
318 template<> struct io_mode_impl<id_> { typedef tag_ type; }; \
319 /**/
320 BOOST_IOSTREAMS_MODE_HELPER(input, 1)
321 BOOST_IOSTREAMS_MODE_HELPER(output, 2)
322 BOOST_IOSTREAMS_MODE_HELPER(bidirectional, 3)
323 BOOST_IOSTREAMS_MODE_HELPER(input_seekable, 4)
324 BOOST_IOSTREAMS_MODE_HELPER(output_seekable, 5)
325 BOOST_IOSTREAMS_MODE_HELPER(seekable, 6)
326 BOOST_IOSTREAMS_MODE_HELPER(dual_seekable, 7)
327 BOOST_IOSTREAMS_MODE_HELPER(bidirectional_seekable, 8)
328 BOOST_IOSTREAMS_MODE_HELPER(dual_use, 9)
329 #undef BOOST_IOSTREAMS_MODE_HELPER
330
331 template<typename T>
332 struct io_mode_id {
333 typedef typename category_of<T>::type category;
334 BOOST_SELECT_BY_SIZE(int, value, detail::io_mode_impl_helper(category()));
335 };
336
337 } // End namespace detail.
338
339 template<typename T> // Borland 5.6.4 requires this circumlocution.
340 struct mode_of : detail::io_mode_impl< detail::io_mode_id<T>::value > { };
341
342 // Partial specialization for reference wrappers
343 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //---------------------------//
344
345 template<typename T>
346 struct mode_of< reference_wrapper<T> >
347 : mode_of<T>
348 { };
349
350 #endif // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //-----------------//
351
352 //------------------Definition of is_device, is_filter and is_direct----------//
353
354 namespace detail {
355
356 template<typename T, typename Tag>
357 struct has_trait_impl {
358 typedef typename category_of<T>::type category;
359 BOOST_STATIC_CONSTANT(bool, value = (is_convertible<category, Tag>::value));
360 };
361
362 template<typename T, typename Tag>
363 struct has_trait
364 : mpl::bool_<has_trait_impl<T, Tag>::value>
365 { };
366
367 } // End namespace detail.
368
369 template<typename T>
370 struct is_device : detail::has_trait<T, device_tag> { };
371
372 template<typename T>
373 struct is_filter : detail::has_trait<T, filter_tag> { };
374
375 template<typename T>
376 struct is_direct : detail::has_trait<T, direct_tag> { };
377
378 //------------------Definition of BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS----------//
379
380 #define BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr) \
381 typedef Tr traits_type; \
382 typedef typename traits_type::int_type int_type; \
383 typedef typename traits_type::off_type off_type; \
384 typedef typename traits_type::pos_type pos_type; \
385 /**/
386
387 } } // End namespaces iostreams, boost.
388
389 #include <boost/iostreams/detail/config/enable_warnings.hpp>
390
391 #endif // #ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED
392