summaryrefslogtreecommitdiffstats
blob: ce522a08429fa6fec1faa2819048061a8e8eadd5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430

// Copyright 2000 John Maddock (john@johnmaddock.co.uk)
// Copyright 2000 Jeremy Siek (jsiek@lsc.nd.edu)
// Copyright 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
//
//  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/type_traits for most recent version including documentation.

#ifndef BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED
#define BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED

#include <boost/type_traits/intrinsics.hpp>
#ifndef BOOST_IS_CONVERTIBLE
#include <boost/type_traits/detail/yes_no_type.hpp>
#include <boost/type_traits/config.hpp>
#include <boost/type_traits/is_array.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/type_traits/ice.hpp>
#include <boost/type_traits/is_arithmetic.hpp>
#include <boost/type_traits/is_void.hpp>
#ifndef BOOST_NO_IS_ABSTRACT
#include <boost/type_traits/is_abstract.hpp>
#endif

#if defined(__MWERKS__)
#include <boost/type_traits/is_function.hpp>
#include <boost/type_traits/remove_reference.hpp>
#endif

#endif // BOOST_IS_CONVERTIBLE

// should be always the last #include directive
#include <boost/type_traits/detail/bool_trait_def.hpp>

namespace boost {

#ifndef BOOST_IS_CONVERTIBLE

// is one type convertable to another?
//
// there are multiple versions of the is_convertible
// template, almost every compiler seems to require its
// own version.
//
// Thanks to Andrei Alexandrescu for the original version of the
// conversion detection technique!
//

namespace detail {

// MS specific version:

#if defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)

// This workaround is necessary to handle when From is void
// which is normally taken care of by the partial specialization
// of the is_convertible typename.
using ::boost::type_traits::yes_type;
using ::boost::type_traits::no_type;

template< typename From >
struct does_conversion_exist
{
    template< typename To > struct result_
    {
        static no_type BOOST_TT_DECL _m_check(...);
        static yes_type BOOST_TT_DECL _m_check(To);
        static From _m_from;
        enum { value = sizeof( _m_check(_m_from) ) == sizeof(yes_type) };
    };
};

template<>
struct does_conversion_exist<void>
{
    template< typename To > struct result_
    {
        enum { value = ::boost::is_void<To>::value };
    };
};

template <typename From, typename To>
struct is_convertible_basic_impl
    : does_conversion_exist<From>::template result_<To>
{
};

#elif defined(__BORLANDC__) && (__BORLANDC__ < 0x560)
//
// special version for Borland compilers
// this version breaks when used for some
// UDT conversions:
//
template <typename From, typename To>
struct is_convertible_impl
{
#pragma option push -w-8074
    // This workaround for Borland breaks the EDG C++ frontend,
    // so we only use it for Borland.
    template <typename T> struct checker
    {
        static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);
        static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(T);
    };

    static From _m_from;
    static bool const value = sizeof( checker<To>::_m_check(_m_from) )
        == sizeof(::boost::type_traits::yes_type);
#pragma option pop
};

#elif defined(__GNUC__) || defined(__BORLANDC__) && (__BORLANDC__ < 0x600)
// special version for gcc compiler + recent Borland versions
// note that this does not pass UDT's through (...)

struct any_conversion
{
    template <typename T> any_conversion(const volatile T&);
    template <typename T> any_conversion(T&);
};

template <typename T> struct checker
{
    static boost::type_traits::no_type _m_check(any_conversion ...);
    static boost::type_traits::yes_type _m_check(T, int);
};

template <typename From, typename To>
struct is_convertible_basic_impl
{
    static From _m_from;
    static bool const value = sizeof( detail::checker<To>::_m_check(_m_from, 0) )
        == sizeof(::boost::type_traits::yes_type);
};

#elif (defined(__EDG_VERSION__) && (__EDG_VERSION__ >= 245) && !defined(__ICL)) \
      || defined(__IBMCPP__) || defined(__HP_aCC)
//
// This is *almost* an ideal world implementation as it doesn't rely
// on undefined behaviour by passing UDT's through (...).
// Unfortunately it doesn't quite pass all the tests for most compilers (sigh...)
// Enable this for your compiler if is_convertible_test.cpp will compile it...
//
// Note we do not enable this for VC7.1, because even though it passes all the
// type_traits tests it is known to cause problems when instantiation occurs
// deep within the instantiation tree :-(
//
struct any_conversion
{
    template <typename T> any_conversion(const volatile T&);
    // we need this constructor to catch references to functions
    // (which can not be cv-qualified):
    template <typename T> any_conversion(T&);
};

template <typename From, typename To>
struct is_convertible_basic_impl
{
    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion ...);
    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int);
       static From _m_from;

    BOOST_STATIC_CONSTANT(bool, value =
        sizeof( _m_check(_m_from, 0) ) == sizeof(::boost::type_traits::yes_type)
        );
};

#elif defined(__DMC__)

struct any_conversion
{
    template <typename T> any_conversion(const volatile T&);
    // we need this constructor to catch references to functions
    // (which can not be cv-qualified):
    template <typename T> any_conversion(T&);
};

template <typename From, typename To>
struct is_convertible_basic_impl
{
    // Using '...' doesn't always work on Digital Mars. This version seems to.
    template <class T>
    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion,  float, T);
    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int, int);
    static From _m_from;

    // Static constants sometime cause the conversion of _m_from to To to be
    // called. This doesn't happen with an enum.
    enum { value =
        sizeof( _m_check(_m_from, 0, 0) ) == sizeof(::boost::type_traits::yes_type)
        };
};

#elif defined(__MWERKS__)
// 
// CW works with the technique implemented above for EDG, except when From
// is a function type (or a reference to such a type), in which case
// any_conversion won't be accepted as a valid conversion. We detect this
// exceptional situation and channel it through an alternative algorithm.
//

template <typename From, typename To,bool FromIsFunctionRef>
struct is_convertible_basic_impl_aux;

struct any_conversion
{
    template <typename T> any_conversion(const volatile T&);
};

template <typename From, typename To>
struct is_convertible_basic_impl_aux<From,To,false /*FromIsFunctionRef*/>
{
    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion ...);
    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int);
    static From _m_from;

    BOOST_STATIC_CONSTANT(bool, value =
        sizeof( _m_check(_m_from, 0) ) == sizeof(::boost::type_traits::yes_type)
        );
};

template <typename From, typename To>
struct is_convertible_basic_impl_aux<From,To,true /*FromIsFunctionRef*/>
{
    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);
    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To);
    static From _m_from;
    BOOST_STATIC_CONSTANT(bool, value =
        sizeof( _m_check(_m_from) ) == sizeof(::boost::type_traits::yes_type)
        );
};

template <typename From, typename To>
struct is_convertible_basic_impl:
  is_convertible_basic_impl_aux<
    From,To,
    ::boost::is_function<typename ::boost::remove_reference<From>::type>::value
  >
{};

#else

//
// This version seems to work pretty well for a wide spectrum of compilers,
// however it does rely on undefined behaviour by passing UDT's through (...).
//
template <typename From, typename To>
struct is_convertible_basic_impl
{
    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);
    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To);
    static From _m_from;
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable:4244)
#if BOOST_WORKAROUND(_MSC_FULL_VER, >= 140050000)
#pragma warning(disable:6334)
#endif
#endif
    BOOST_STATIC_CONSTANT(bool, value =
        sizeof( _m_check(_m_from) ) == sizeof(::boost::type_traits::yes_type)
        );
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
};

#endif // is_convertible_impl

#if defined(__DMC__)
// As before, a static constant sometimes causes errors on Digital Mars.
template <typename From, typename To>
struct is_convertible_impl
{
    typedef typename add_reference<From>::type ref_type;
    enum { value =
        (::boost::type_traits::ice_and<
            ::boost::type_traits::ice_or<
               ::boost::detail::is_convertible_basic_impl<ref_type,To>::value,
               ::boost::is_void<To>::value
            >::value,
            ::boost::type_traits::ice_not<
               ::boost::is_array<To>::value
            >::value
        >::value) };
};
#elif !defined(__BORLANDC__) || __BORLANDC__ > 0x551
template <typename From, typename To>
struct is_convertible_impl
{
    typedef typename add_reference<From>::type ref_type;
    BOOST_STATIC_CONSTANT(bool, value =
        (::boost::type_traits::ice_and<
            ::boost::type_traits::ice_or<
               ::boost::detail::is_convertible_basic_impl<ref_type,To>::value,
               ::boost::is_void<To>::value
            >::value,
            ::boost::type_traits::ice_not<
               ::boost::is_array<To>::value
            >::value
        >::value)
        );
};
#endif

template <bool trivial1, bool trivial2, bool abstract_target>
struct is_convertible_impl_select
{
   template <class From, class To>
   struct rebind
   {
      typedef is_convertible_impl<From, To> type;
   };
};

template <>
struct is_convertible_impl_select<true, true, false>
{
   template <class From, class To>
   struct rebind
   {
      typedef true_type type;
   };
};

template <>
struct is_convertible_impl_select<false, false, true>
{
   template <class From, class To>
   struct rebind
   {
      typedef false_type type;
   };
};

template <>
struct is_convertible_impl_select<true, false, true>
{
   template <class From, class To>
   struct rebind
   {
      typedef false_type type;
   };
};

template <typename From, typename To>
struct is_convertible_impl_dispatch_base
{
#if !BOOST_WORKAROUND(__HP_aCC, < 60700)
   typedef is_convertible_impl_select< 
      ::boost::is_arithmetic<From>::value, 
      ::boost::is_arithmetic<To>::value,
#ifndef BOOST_NO_IS_ABSTRACT
      ::boost::is_abstract<To>::value
#else
      false
#endif
   > selector;
#else
   typedef is_convertible_impl_select<false, false, false> selector;
#endif
   typedef typename selector::template rebind<From, To> isc_binder;
   typedef typename isc_binder::type type;
};

template <typename From, typename To>
struct is_convertible_impl_dispatch 
   : public is_convertible_impl_dispatch_base<From, To>::type
{};

//
// Now add the full and partial specialisations
// for void types, these are common to all the
// implementation above:
//
#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
#   define TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1,spec2,value) \
    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2,value) \
    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 const,value) \
    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 volatile,value) \
    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 const volatile,value) \
    /**/

#   define TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2(trait,spec1,spec2,value) \
    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1,spec2,value) \
    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 const,spec2,value) \
    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 volatile,spec2,value) \
    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 const volatile,spec2,value) \
    /**/

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2(is_convertible,void,void,true)

#   undef TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2
#   undef TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1

#else
    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(is_convertible,void,void,true)
#endif // BOOST_NO_CV_VOID_SPECIALIZATIONS

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void,To,false)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void,true)
#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void const,To,false)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void volatile,To,false)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void const volatile,To,false)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void const,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void volatile,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void const volatile,true)
#endif
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

} // namespace detail

BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_convertible,From,To,(::boost::detail::is_convertible_impl_dispatch<From,To>::value))

#else

BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_convertible,From,To,BOOST_IS_CONVERTIBLE(From,To))

#endif

} // namespace boost

#include <boost/type_traits/detail/bool_trait_undef.hpp>

#endif // BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED