ceph/src/boost/libs/parameter/test/optional_deduced_sfinae.cpp

   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
  93         sfinae(A0 const& a0)
  94     {
  95         return 0;
  96     }
  97 } // namespace test
  98
  99 #include <boost/core/lightweight_test.hpp>
 100
 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