1 // Copyright David Abrahams 2006. Distributed under the Boost
2 // Software License, Version 1.0. (See accompanying
3 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
4 #ifndef BOOST_CONCEPT_REQUIRES_DWA2006430_HPP
5 # define BOOST_CONCEPT_REQUIRES_DWA2006430_HPP
6 
7 # include <boost/config.hpp>
8 # include <boost/concept/assert.hpp>
9 # include <boost/preprocessor/seq/for_each.hpp>
10 
11 namespace boost {
12 
13 // unaryfunptr_arg_type from parameter/aux_/parenthesized_type.hpp
14 
15 namespace ccheck_aux {
16 
17 // A metafunction that transforms void(*)(T) -> T
18 template <class UnaryFunctionPointer>
19 struct unaryfunptr_arg_type;
20 
21 template <class Arg>
22 struct unaryfunptr_arg_type<void(*)(Arg)>
23 {
24     typedef Arg type;
25 };
26 
27 template <>
28 struct unaryfunptr_arg_type<void(*)(void)>
29 {
30     typedef void type;
31 };
32 
33 } // namespace ccheck_aux
34 
35 // Template for use in handwritten assertions
36 template <class Model, class More>
37 struct requires_ : More
38 {
39     BOOST_CONCEPT_ASSERT((Model));
40 };
41 
42 // Template for use by macros, where models must be wrapped in parens.
43 // This isn't in namespace detail to keep extra cruft out of resulting
44 // error messages.
45 template <class ModelFn>
46 struct _requires_
47 {
48     enum { value = 0 };
49     BOOST_CONCEPT_ASSERT_FN(ModelFn);
50 };
51 
52 template <int check, class Result>
53 struct Requires_ : ::boost::ccheck_aux::unaryfunptr_arg_type<Result>
54 {
55 };
56 
57 # if BOOST_WORKAROUND(BOOST_INTEL_WIN, BOOST_TESTED_AT(1010))
58 #  define BOOST_CONCEPT_REQUIRES_(r,data,t) | (::boost::_requires_<void(*)t>::value)
59 # else
60 #  define BOOST_CONCEPT_REQUIRES_(r,data,t) + (::boost::_requires_<void(*)t>::value)
61 # endif
62 
63 #if defined(NDEBUG)
64 
65 # define BOOST_CONCEPT_REQUIRES(models, result)                                    \
66     typename ::boost::ccheck_aux::unaryfunptr_arg_type<void(*)result>::type
67 
68 #elif BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
69 
70 // Same thing as below without the initial typename
71 # define BOOST_CONCEPT_REQUIRES(models, result)                                \
72     ::boost::Requires_<                                                        \
73       (0 BOOST_PP_SEQ_FOR_EACH(BOOST_CONCEPT_REQUIRES_, ~, models)),           \
74       ::boost::ccheck_aux::unaryfunptr_arg_type<void(*)result>          \
75                      >::type
76 
77 #else
78 
79 // This just ICEs on MSVC6 :(
80 # define BOOST_CONCEPT_REQUIRES(models, result)                                        \
81     typename ::boost::Requires_<                                                       \
82       (0 BOOST_PP_SEQ_FOR_EACH(BOOST_CONCEPT_REQUIRES_, ~, models)),                   \
83       void(*)result                                                                 \
84     >::type
85 
86 #endif
87 
88 // C++0x proposed syntax changed.  This supports an older usage
89 #define BOOST_CONCEPT_WHERE(models,result) BOOST_CONCEPT_REQUIRES(models,result)
90 
91 } // namespace boost::concept_check
92 
93 #endif // BOOST_CONCEPT_REQUIRES_DWA2006430_HPP
94