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
27namespace boost {
28namespace type_erasure {
29namespace detail {
30
31template<class T>
32struct is_non_const_ref : boost::mpl::false_ {};
33template<class T>
34struct is_non_const_ref<T&> : boost::mpl::true_ {};
35template<class T>
36struct is_non_const_ref<const T&> : boost::mpl::false_ {};
37
38template<class Placeholder, class Base>
39struct 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
48template<class Placeholder, class Base>
49struct 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
60template<class Base>
61struct 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
77template<class T>
78struct uncallable {};
79
80template<class Placeholder, class Base>
81struct 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
101template<class Placeholder, class Base>
102struct 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
123

source code of boost/libs/type_erasure/include/boost/type_erasure/detail/const.hpp