boost/boost/type_traits/is_enum.hpp

   1
   2 // (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes, Howard
   3 // Hinnant & John Maddock 2000.  Permission to copy, use, modify,
   4 // sell and distribute this software is granted provided this
   5 // copyright notice appears in all copies. This software is provided
   6 // "as is" without express or implied warranty, and with no claim as
   7 // to its suitability for any purpose.
   8 //
   9 // See http://www.boost.org for most recent version including documentation.
  10
  11 #ifndef BOOST_TT_IS_ENUM_HPP_INCLUDED
  12 #define BOOST_TT_IS_ENUM_HPP_INCLUDED
  13
  14 #include "boost/type_traits/add_reference.hpp"
  15 #include "boost/type_traits/is_arithmetic.hpp"
  16 #include "boost/type_traits/is_reference.hpp"
  17 #include "boost/type_traits/is_convertible.hpp"
  18 #include "boost/type_traits/config.hpp"
  19
  20 #ifdef BOOST_TT_HAS_CONFORMING_IS_CLASS_IMPLEMENTATION
  21 #   include "boost/type_traits/is_class.hpp"
  22 #endif
  23
  24 // should be the last #include
  25 #include "boost/type_traits/detail/bool_trait_def.hpp"
  26
  27 namespace boost {
  28
  29 #if !(defined(__BORLANDC__) && (__BORLANDC__ <= 0x551))
  30
  31 namespace detail {
  32
  33 struct int_convertible
  34 {
  35     int_convertible(int);
  36 };
  37
  38 // Don't evaluate convertibility to int_convertible unless the type
  39 // is non-arithmetic. This suppresses warnings with GCC.
  40 template <bool is_typename_arithmetic_or_reference = true>
  41 struct is_enum_helper
  42 {
  43     template <typename T> struct type
  44     {
  45         BOOST_STATIC_CONSTANT(bool, value = false);
  46     };
  47 };
  48
  49 template <>
  50 struct is_enum_helper<false>
  51 {
  52     template <typename T> struct type
  53         : ::boost::is_convertible<T,::boost::detail::int_convertible>
  54     {
  55     };
  56 };
  57
  58 template <typename T> struct is_enum_impl
  59 {
  60    typedef ::boost::add_reference<T> ar_t;
  61    typedef typename ar_t::type r_type;
  62
  63 #if defined(BOOST_TT_HAS_CONFORMING_IS_CLASS_IMPLEMENTATION)
  64    BOOST_STATIC_CONSTANT(bool, selector =
  65       (::boost::type_traits::ice_or<
  66            ::boost::is_arithmetic<T>::value
  67          , ::boost::is_reference<T>::value
  68        // We MUST do this on conforming compilers in order to
  69        // correctly deduce that noncopyable types are not enums (dwa
  70        // 2002/04/15)...
  71          , ::boost::is_class<T>::value
  72       >::value));
  73 #else
  74    BOOST_STATIC_CONSTANT(bool, selector =
  75       (::boost::type_traits::ice_or<
  76            ::boost::is_arithmetic<T>::value
  77          , ::boost::is_reference<T>::value
  78        // However, not doing this on non-conforming compilers prevents
  79        // a dependency recursion.
  80       >::value));
  81 #endif
  82
  83 #ifdef __BORLANDC__
  84     typedef ::boost::detail::is_enum_helper<
  85           ::boost::detail::is_enum_impl<T>::selector
  86         > se_t;
  87 #else
  88     typedef ::boost::detail::is_enum_helper<selector> se_t;
  89 #endif
  90     typedef typename se_t::template type<r_type> helper;
  91     BOOST_STATIC_CONSTANT(bool, value = helper::value);
  92 };
  93
  94 // Specializations suppress some nasty warnings with GCC
  95 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,float,false)
  96 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,double,false)
  97 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,long double,false)
  98 // these help on compilers with no partial specialization support:
  99 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,void,false)
 100 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
 101 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,void const,false)
 102 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,void volatile,false)
 103 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_enum,void const volatile,false)
 104 #endif
 105
 106 } // namespace detail
 107
 108 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_enum,T,::boost::detail::is_enum_impl<T>::value)
 109
 110 #else // __BORLANDC__
 111 //
 112 // buggy is_convertible prevents working
 113 // implementation of is_enum:
 114 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_enum,T,false)
 115
 116 #endif
 117
 118 } // namespace boost
 119
 120 #include "boost/type_traits/detail/bool_trait_undef.hpp"
 121
 122 #endif // BOOST_TT_IS_ENUM_HPP_INCLUDED