1 // Copyright Daniel Wallin 2006.
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5
6 #include <boost/parameter/config.hpp>
7
8 #if (BOOST_PARAMETER_MAX_ARITY < 2)
9 #error Define BOOST_PARAMETER_MAX_ARITY as 2 or greater.
10 #endif
11 #if !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING) && \
12 (BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY < 2)
13 #error Define BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY \
14 as 2 or greater.
15 #endif
16
17 #include <boost/parameter/preprocessor.hpp>
18 #include <boost/parameter/name.hpp>
19 #include <boost/parameter/aux_/preprocessor/nullptr.hpp>
20 #include <boost/tuple/tuple.hpp>
21 #include <boost/core/enable_if.hpp>
22 #include <string>
23
24 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
25 #include <boost/mp11/utility.hpp>
26 #include <type_traits>
27 #else
28 #include <boost/mpl/bool.hpp>
29 #include <boost/mpl/if.hpp>
30 #include <boost/type_traits/is_convertible.hpp>
31 #endif
32
33 namespace test {
34
35 BOOST_PARAMETER_NAME(x)
36
37 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
38 template <typename T, typename Args>
39 using predicate = std::is_convertible<T,char const*>;
40
41 BOOST_PARAMETER_FUNCTION((int), sfinae, test::tag,
42 (deduced
43 (optional
44 (x
45 , *(boost::mp11::mp_quote<test::predicate>)
46 , static_cast<char const*>(BOOST_PARAMETER_AUX_PP_NULLPTR)
47 )
48 )
49 )
50 )
51 #else // !defined(BOOST_PARAMETER_CAN_USE_MP11)
52 struct predicate
53 {
54 template <typename T, typename Args>
55 struct apply
56 : boost::mpl::if_<
57 boost::is_convertible<T,char const*>
58 , boost::mpl::true_
59 , boost::mpl::false_
60 >
61 {
62 };
63 };
64
65 BOOST_PARAMETER_FUNCTION((int), sfinae, test::tag,
66 (deduced
67 (optional
68 (x
69 , *(test::predicate)
70 , static_cast<char const*>(BOOST_PARAMETER_AUX_PP_NULLPTR)
71 )
72 )
73 )
74 )
75 #endif // BOOST_PARAMETER_CAN_USE_MP11
76 {
77 return 1;
78 }
79
80 template <typename A0>
81 typename boost::enable_if<
82 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
83 std::is_same<int,A0>
84 #else
85 typename boost::mpl::if_<
86 boost::is_same<int,A0>
87 , boost::mpl::true_
88 , boost::mpl::false_
89 >::type
90 #endif
91 , int
92 >::type
sfinae(A0 const & a0)93 sfinae(A0 const& a0)
94 {
95 return 0;
96 }
97 } // namespace test
98
99 #include <boost/core/lightweight_test.hpp>
100
main()101 int main()
102 {
103 BOOST_TEST_EQ(1, test::sfinae());
104 BOOST_TEST_EQ(1, test::sfinae("foo"));
105 BOOST_TEST_EQ(0, test::sfinae(1));
106 return boost::report_errors();
107 }
108
109