ceph/src/boost/libs/type_erasure/include/boost/type_erasure/detail/const.hpp

   1 // Boost.TypeErasure library
   2 //
   3 // Copyright 2012 Steven Watanabe
   4 //
   5 // Distributed under the Boost Software License Version 1.0. (See
   6 // accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 //
   9 // $Id$
  10
  11 #ifndef BOOST_TYPE_ERASURE_DETAIL_CONST_HPP_INCLUDED
  12 #define BOOST_TYPE_ERASURE_DETAIL_CONST_HPP_INCLUDED
  13
  14 #include <boost/mpl/if.hpp>
  15 #include <boost/mpl/bool.hpp>
  16 #include <boost/mpl/or.hpp>
  17 #include <boost/mpl/and.hpp>
  18 #include <boost/mpl/not.hpp>
  19 #include <boost/type_traits/is_same.hpp>
  20 #include <boost/type_traits/is_const.hpp>
  21 #include <boost/type_traits/is_reference.hpp>
  22 #include <boost/type_traits/remove_reference.hpp>
  23 #include <boost/type_traits/remove_cv.hpp>
  24 #include <boost/type_erasure/placeholder_of.hpp>
  25 #include <boost/type_erasure/derived.hpp>
  26
  27 namespace boost {
  28 namespace type_erasure {
  29 namespace detail {
  30
  31 template<class T>
  32 struct is_non_const_ref : boost::mpl::false_ {};
  33 template<class T>
  34 struct is_non_const_ref<T&> : boost::mpl::true_ {};
  35 template<class T>
  36 struct is_non_const_ref<const T&> : boost::mpl::false_ {};
  37
  38 template<class Placeholder, class Base>
  39 struct should_be_const :
  40     ::boost::mpl::or_<
  41         ::boost::is_const<Placeholder>,
  42         ::boost::type_erasure::detail::is_non_const_ref<
  43             typename ::boost::type_erasure::placeholder_of<Base>::type
  44         >
  45     >
  46 {};
  47
  48 template<class Placeholder, class Base>
  49 struct should_be_non_const :
  50     ::boost::mpl::and_<
  51         ::boost::mpl::not_< ::boost::is_const<Placeholder> >,
  52         ::boost::mpl::not_<
  53             ::boost::is_reference<
  54                 typename ::boost::type_erasure::placeholder_of<Base>::type
  55             >
  56         >
  57     >
  58 {};
  59
  60 template<class Base>
  61 struct non_const_this_param
  62 {
  63     typedef typename ::boost::type_erasure::placeholder_of<Base>::type placeholder;
  64     typedef typename ::boost::type_erasure::derived<Base>::type plain_type;
  65     typedef typename ::boost::mpl::if_<
  66         ::boost::is_same<
  67             placeholder,
  68             typename ::boost::remove_cv<
  69                 typename ::boost::remove_reference<placeholder>::type
  70             >::type&
  71         >,
  72         const plain_type,
  73         plain_type
  74     >::type type;
  75 };
  76
  77 template<class T>
  78 struct uncallable {};
  79
  80 template<class Placeholder, class Base>
  81 struct maybe_const_this_param
  82 {
  83     typedef typename ::boost::type_erasure::derived<Base>::type plain_type;
  84     typedef typename ::boost::remove_reference<Placeholder>::type plain_placeholder;
  85     typedef typename ::boost::mpl::if_< ::boost::is_reference<Placeholder>,
  86         typename ::boost::mpl::if_<
  87             ::boost::type_erasure::detail::should_be_non_const<plain_placeholder, Base>,
  88             plain_type&,
  89             typename ::boost::mpl::if_<
  90                 ::boost::type_erasure::detail::should_be_const<plain_placeholder, Base>,
  91                 const plain_type&,
  92                 uncallable<plain_type>
  93             >::type
  94         >::type,
  95         plain_type
  96     >::type type;
  97 };
  98
  99 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
 100
 101 template<class Placeholder, class Base>
 102 struct maybe_const_this_param<Placeholder&&, Base>
 103 {
 104     typedef typename ::boost::type_erasure::derived<Base>::type plain_type;
 105     typedef typename ::boost::remove_reference<Placeholder>::type plain_placeholder;
 106     typedef typename ::boost::type_erasure::placeholder_of<plain_type>::type self_placeholder;
 107     typedef typename ::boost::mpl::if_< ::boost::is_lvalue_reference<self_placeholder>,
 108         ::boost::type_erasure::detail::uncallable<plain_type>,
 109         typename ::boost::mpl::if_< ::boost::is_rvalue_reference<self_placeholder>,
 110             const plain_type&,
 111             plain_type&&
 112         >::type
 113     >::type type;
 114 };
 115
 116 #endif
 117
 118 }
 119 }
 120 }
 121
 122 #endif