1// boost utility/base_from_member.hpp header file --------------------------//
2
3// Copyright 2001, 2003, 2004, 2012 Daryle Walker. Use, modification, and
4// distribution are subject to the Boost Software License, Version 1.0. (See
5// accompanying file LICENSE_1_0.txt or a copy at
6// <http://www.boost.org/LICENSE_1_0.txt>.)
7
8// See <http://www.boost.org/libs/utility/> for the library's home page.
9
10#ifndef BOOST_UTILITY_BASE_FROM_MEMBER_HPP
11#define BOOST_UTILITY_BASE_FROM_MEMBER_HPP
12
13#include <boost/config.hpp>
14#include <boost/preprocessor/arithmetic/inc.hpp>
15#include <boost/preprocessor/repetition/enum_binary_params.hpp>
16#include <boost/preprocessor/repetition/enum_params.hpp>
17#include <boost/preprocessor/repetition/repeat_from_to.hpp>
18#include <boost/type_traits/is_same.hpp>
19#include <boost/type_traits/remove_cv.hpp>
20#include <boost/type_traits/remove_reference.hpp>
21#include <boost/utility/enable_if.hpp>
22
23
24// Base-from-member arity configuration macro ------------------------------//
25
26// The following macro determines how many arguments will be in the largest
27// constructor template of base_from_member. Constructor templates will be
28// generated from one argument to this maximum. Code from other files can read
29// this number if they need to always match the exact maximum base_from_member
30// uses. The maximum constructor length can be changed by overriding the
31// #defined constant. Make sure to apply the override, if any, for all source
32// files during project compiling for consistency.
33
34// Contributed by Jonathan Turkanis
35
36#ifndef BOOST_BASE_FROM_MEMBER_MAX_ARITY
37#define BOOST_BASE_FROM_MEMBER_MAX_ARITY 10
38#endif
39
40
41// An iteration of a constructor template for base_from_member -------------//
42
43// A macro that should expand to:
44// template < typename T1, ..., typename Tn >
45// base_from_member( T1 x1, ..., Tn xn )
46// : member( x1, ..., xn )
47// {}
48// This macro should only persist within this file.
49
50#ifndef BOOST_UTILITY_DOCS
51#define BOOST_PRIVATE_CTR_DEF( z, n, data ) \
52 template < BOOST_PP_ENUM_PARAMS(n, typename T) > \
53 base_from_member( BOOST_PP_ENUM_BINARY_PARAMS(n, T, x) ) \
54 : member( BOOST_PP_ENUM_PARAMS(n, x) ) \
55 {} \
56 /**/
57#endif // BOOST_UTILITY_DOCS
58
59namespace boost
60{
61
62namespace detail
63{
64
65// Type-unmarking class template -------------------------------------------//
66
67// Type-trait to get the raw type, i.e. the type without top-level reference nor
68// cv-qualification, from a type expression. Mainly for function arguments, any
69// reference part is stripped first.
70
71// Contributed by Daryle Walker
72
73template < typename T >
74struct remove_cv_ref
75{
76 typedef typename ::boost::remove_cv<typename
77 ::boost::remove_reference<T>::type>::type type;
78
79}; // boost::detail::remove_cv_ref
80
81// Unmarked-type comparison class template ---------------------------------//
82
83// Type-trait to check if two type expressions have the same raw type.
84
85// Contributed by Daryle Walker, based on a work-around by Luc Danton
86
87template < typename T, typename U >
88struct is_related
89 : public ::boost::is_same<
90 typename ::boost::detail::remove_cv_ref<T>::type,
91 typename ::boost::detail::remove_cv_ref<U>::type >
92{};
93
94// Enable-if-on-unidentical-unmarked-type class template -------------------//
95
96// Enable-if on the first two type expressions NOT having the same raw type.
97
98// Contributed by Daryle Walker, based on a work-around by Luc Danton
99
100#ifndef BOOST_NO_CXX11_VARIADIC_TEMPLATES
101template<typename ...T>
102struct enable_if_unrelated
103 : public ::boost::enable_if_c<true>
104{};
105
106template<typename T, typename U, typename ...U2>
107struct enable_if_unrelated<T, U, U2...>
108 : public ::boost::disable_if< ::boost::detail::is_related<T, U> >
109{};
110#endif
111
112} // namespace boost::detail
113
114
115// Base-from-member class template -----------------------------------------//
116
117// Helper to initialize a base object so a derived class can use this
118// object in the initialization of another base class. Used by
119// Dietmar Kuehl from ideas by Ron Klatcho to solve the problem of a
120// base class needing to be initialized by a member.
121
122// Contributed by Daryle Walker
123
124template < typename MemberType, int UniqueID = 0 >
125class base_from_member
126{
127protected:
128 MemberType member;
129
130#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && \
131 !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && \
132 !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) && \
133 !(defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 4))
134 template <typename ...T, typename EnableIf = typename
135 ::boost::detail::enable_if_unrelated<base_from_member, T...>::type>
136 explicit BOOST_CONSTEXPR base_from_member( T&& ...x )
137 BOOST_NOEXCEPT_IF( BOOST_NOEXCEPT_EXPR(::new ((void*) 0) MemberType(
138 static_cast<T&&>(x)... )) ) // no std::is_nothrow_constructible...
139 : member( static_cast<T&&>(x)... ) // ...nor std::forward needed
140 {}
141#else
142 base_from_member()
143 : member()
144 {}
145
146 template < typename T0 > explicit base_from_member( T0 x0 ) : member( x0 ) {}
147 BOOST_PP_REPEAT_FROM_TO( 2, BOOST_PP_INC(BOOST_BASE_FROM_MEMBER_MAX_ARITY),
148 BOOST_PRIVATE_CTR_DEF, _ )
149#endif
150
151}; // boost::base_from_member
152
153template < typename MemberType, int UniqueID >
154class base_from_member<MemberType&, UniqueID>
155{
156protected:
157 MemberType& member;
158
159 explicit BOOST_CONSTEXPR base_from_member( MemberType& x )
160 BOOST_NOEXCEPT
161 : member( x )
162 {}
163
164}; // boost::base_from_member
165
166} // namespace boost
167
168
169// Undo any private macros
170#undef BOOST_PRIVATE_CTR_DEF
171
172
173#endif // BOOST_UTILITY_BASE_FROM_MEMBER_HPP
174