1// (C) Copyright Dave Abrahams, Steve Cleary, Beman Dawes, Howard
2// Hinnant & John Maddock 2000-2003.
3// Use, modification and distribution are subject to the Boost Software License,
4// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt).
6//
7// See http://www.boost.org/libs/type_traits for most recent version including documentation.
8
9
10#ifndef BOOST_TT_IS_CLASS_HPP_INCLUDED
11#define BOOST_TT_IS_CLASS_HPP_INCLUDED
12
13#include <boost/type_traits/detail/config.hpp>
14#include <boost/type_traits/intrinsics.hpp>
15#include <boost/type_traits/integral_constant.hpp>
16#ifndef BOOST_IS_CLASS
17# include <boost/type_traits/is_union.hpp>
18
19#ifdef BOOST_TT_HAS_CONFORMING_IS_CLASS_IMPLEMENTATION
20# include <boost/type_traits/detail/yes_no_type.hpp>
21#else
22# include <boost/type_traits/is_scalar.hpp>
23# include <boost/type_traits/is_array.hpp>
24# include <boost/type_traits/is_reference.hpp>
25# include <boost/type_traits/is_void.hpp>
26# include <boost/type_traits/is_function.hpp>
27#endif
28
29#endif // BOOST_IS_CLASS
30
31namespace boost {
32
33namespace detail {
34
35#ifndef BOOST_IS_CLASS
36#ifdef BOOST_TT_HAS_CONFORMING_IS_CLASS_IMPLEMENTATION
37
38// This is actually the conforming implementation which works with
39// abstract classes. However, enough compilers have trouble with
40// it that most will use the one in
41// boost/type_traits/object_traits.hpp. This implementation
42// actually works with VC7.0, but other interactions seem to fail
43// when we use it.
44
45// is_class<> metafunction due to Paul Mensonides
46// (leavings@attbi.com). For more details:
47// http://groups.google.com/groups?hl=en&selm=000001c1cc83%24e154d5e0%247772e50c%40c161550a&rnum=1
48#if defined(__GNUC__) && !defined(__EDG_VERSION__)
49
50template <class U> ::boost::type_traits::yes_type is_class_tester(void(U::*)(void));
51template <class U> ::boost::type_traits::no_type is_class_tester(...);
52
53template <typename T>
54struct is_class_impl
55{
56
57 BOOST_STATIC_CONSTANT(bool, value =
58 sizeof(is_class_tester<T>(0)) == sizeof(::boost::type_traits::yes_type)
59 && ! ::boost::is_union<T>::value
60 );
61};
62
63#else
64
65template <typename T>
66struct is_class_impl
67{
68 template <class U> static ::boost::type_traits::yes_type is_class_tester(void(U::*)(void));
69 template <class U> static ::boost::type_traits::no_type is_class_tester(...);
70
71 BOOST_STATIC_CONSTANT(bool, value =
72 sizeof(is_class_tester<T>(0)) == sizeof(::boost::type_traits::yes_type)
73 && ! ::boost::is_union<T>::value
74 );
75};
76
77#endif
78
79#else
80
81template <typename T>
82struct is_class_impl
83{
84 BOOST_STATIC_CONSTANT(bool, value =
85 ! ::boost::is_union<T>::value >::value
86 && ! ::boost::is_scalar<T>::value
87 && ! ::boost::is_array<T>::value
88 && ! ::boost::is_reference<T>::value
89 && ! ::boost::is_void<T>::value
90 && ! ::boost::is_function<T>::value
91 );
92};
93
94# endif // BOOST_TT_HAS_CONFORMING_IS_CLASS_IMPLEMENTATION
95# else // BOOST_IS_CLASS
96template <typename T>
97struct is_class_impl
98{
99 BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_CLASS(T));
100};
101# endif // BOOST_IS_CLASS
102
103} // namespace detail
104
105template <class T> struct is_class : public integral_constant<bool, ::boost::detail::is_class_impl<T>::value> {};
106# ifdef __EDG_VERSION__
107template <class T> struct is_class<const T> : public is_class<T>{};
108template <class T> struct is_class<const volatile T> : public is_class<T>{};
109template <class T> struct is_class<volatile T> : public is_class<T>{};
110# endif
111
112} // namespace boost
113
114#endif // BOOST_TT_IS_CLASS_HPP_INCLUDED
115

source code of include/boost/type_traits/is_class.hpp