boost/type_traits/is_abstract.hpp

   1 #ifndef BOOST_TT_IS_ABSTRACT_CLASS_HPP
   2 #define BOOST_TT_IS_ABSTRACT_CLASS_HPP
   3
   4 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   5 # pragma once
   6 #endif
   7
   8 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
   9 // is_abstract_class.hpp:
  10 //
  11 //  (C) Copyright 2002 Rani Sharoni (rani_sharoni@hotmail.com) and Robert Ramey
  12 //  Use, modification and distribution is subject to the Boost Software
  13 //  License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  14 //  http://www.boost.org/LICENSE_1_0.txt)
  15 //
  16 //  See http://www.boost.org for updates, documentation, and revision history.
  17 //
  18
  19 // Compile type discovery whether given type is abstract class or not.
  20 //
  21 //   Requires DR 337 to be supported by compiler
  22 //   (http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_active.html#337).
  23 //
  24 //
  25 // Believed (Jan 2004) to work on:
  26 //  - GCC 3.4
  27 //  - VC++ 7.1
  28 //  - compilers with new EDG frontend (Intel C++ 7, Comeau 4.3.2)
  29 //
  30 // Doesn't work on:
  31 //  - VC++6, VC++7.0 and less
  32 //  - GCC 3.3.X and less
  33 //  - Borland C++ 6 and less
  34 //
  35 //
  36 // History:
  37 //  - Originally written by Rani Sharoni, see
  38 //    http://groups.google.com/groups?selm=df893da6.0207110613.75b2fe90%40posting.google.com
  39 //    At this time supported by EDG (Intel C++ 7, Comeau 4.3.2) and VC7.1.
  40 //  - Adapted and added into Boost.Serialization library by Robert Ramey
  41 //    (starting with submission #10).
  42 //  - Jan 2004: GCC 3.4 fixed to suport DR337 (Giovanni Bajo).
  43 //  - Jan 2004: modified to be part of Boost.TypeTraits (Pavel Vozenilek).
  44 //  - Nov 2004: Christoph Ludwig found that the implementation did not work with
  45 //              template types and gcc-3.4 or VC7.1, fix due to Christoph Ludwig
  46 //              and John Maddock.
  47 //  - Dec 2004: Added new config macro BOOST_NO_IS_ABSTRACT which causes the template
  48 //              to degrade gracefully, rather than trash the compiler (John Maddock).
  49 //
  50
  51 #include <boost/type_traits/intrinsics.hpp>
  52 #ifndef BOOST_IS_ABSTRACT
  53 #include <boost/static_assert.hpp>
  54 #include <boost/type_traits/detail/yes_no_type.hpp>
  55 #include <boost/type_traits/is_class.hpp>
  56 #include <boost/type_traits/detail/ice_and.hpp>
  57 #ifdef BOOST_NO_IS_ABSTRACT
  58 #include <boost/type_traits/is_polymorphic.hpp>
  59 #endif
  60 #endif
  61 // should be the last #include
  62 #include <boost/type_traits/detail/bool_trait_def.hpp>
  63
  64
  65 namespace boost {
  66 namespace detail{
  67
  68 #ifdef BOOST_IS_ABSTRACT
  69 template <class T>
  70 struct is_abstract_imp
  71 {
  72    BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_ABSTRACT(T));
  73 };
  74 #elif !defined(BOOST_NO_IS_ABSTRACT)
  75 template<class T>
  76 struct is_abstract_imp2
  77 {
  78    // Deduction fails if T is void, function type,
  79    // reference type (14.8.2/2)or an abstract class type
  80    // according to review status issue #337
  81    //
  82    template<class U>
  83    static type_traits::no_type check_sig(U (*)[1]);
  84    template<class U>
  85    static type_traits::yes_type check_sig(...);
  86    //
  87    // T must be a complete type, further if T is a template then
  88    // it must be instantiated in order for us to get the right answer:
  89    //
  90    BOOST_STATIC_ASSERT(sizeof(T) != 0);
  91
  92    // GCC2 won't even parse this template if we embed the computation
  93    // of s1 in the computation of value.
  94 #ifdef __GNUC__
  95    BOOST_STATIC_CONSTANT(std::size_t, s1 = sizeof(is_abstract_imp2<T>::template check_sig<T>(0)));
  96 #else
  97 #if BOOST_WORKAROUND(_MSC_FULL_VER, >= 140050000)
  98 #pragma warning(push)
  99 #pragma warning(disable:6334)
 100 #endif
 101    BOOST_STATIC_CONSTANT(std::size_t, s1 = sizeof(check_sig<T>(0)));
 102 #if BOOST_WORKAROUND(_MSC_FULL_VER, >= 140050000)
 103 #pragma warning(pop)
 104 #endif
 105 #endif
 106
 107    BOOST_STATIC_CONSTANT(bool, value =
 108       (s1 == sizeof(type_traits::yes_type)));
 109 };
 110
 111 template <bool v>
 112 struct is_abstract_select
 113 {
 114    template <class T>
 115    struct rebind
 116    {
 117       typedef is_abstract_imp2<T> type;
 118    };
 119 };
 120 template <>
 121 struct is_abstract_select<false>
 122 {
 123    template <class T>
 124    struct rebind
 125    {
 126       typedef false_type type;
 127    };
 128 };
 129
 130 template <class T>
 131 struct is_abstract_imp
 132 {
 133    typedef is_abstract_select< ::boost::is_class<T>::value> selector;
 134    typedef typename selector::template rebind<T> binder;
 135    typedef typename binder::type type;
 136
 137    BOOST_STATIC_CONSTANT(bool, value = type::value);
 138 };
 139
 140 #endif
 141 }
 142
 143 #ifndef BOOST_NO_IS_ABSTRACT
 144 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_abstract,T,::boost::detail::is_abstract_imp<T>::value)
 145 #else
 146 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_abstract,T,::boost::detail::is_polymorphic_imp<T>::value)
 147 #endif
 148
 149 } // namespace boost
 150
 151 #include <boost/type_traits/detail/bool_trait_undef.hpp>
 152
 153 #endif //BOOST_TT_IS_ABSTRACT_CLASS_HPP