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       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             : #define BOOST_PRIVATE_CTR_DEF( z, n, data )                   \
      51             :     template < BOOST_PP_ENUM_PARAMS(n, typename T) >          \
      52             :     base_from_member( BOOST_PP_ENUM_BINARY_PARAMS(n, T, x) )  \
      53             :         : member( BOOST_PP_ENUM_PARAMS(n, x) )                \
      54             :         {}                                                    \
      55             :     /**/
      56             : 
      57             : 
      58             : namespace boost
      59             : {
      60             : 
      61             : namespace detail
      62             : {
      63             : 
      64             : //  Type-unmarking class template  -------------------------------------------//
      65             : 
      66             : // Type-trait to get the raw type, i.e. the type without top-level reference nor
      67             : // cv-qualification, from a type expression.  Mainly for function arguments, any
      68             : // reference part is stripped first.
      69             : 
      70             : // Contributed by Daryle Walker
      71             : 
      72             : template < typename T >
      73             : struct remove_cv_ref
      74             : {
      75             :     typedef typename ::boost::remove_cv<typename
      76             :      ::boost::remove_reference<T>::type>::type  type;
      77             : 
      78             : };  // boost::detail::remove_cv_ref
      79             : 
      80             : //  Unmarked-type comparison class template  ---------------------------------//
      81             : 
      82             : // Type-trait to check if two type expressions have the same raw type.
      83             : 
      84             : // Contributed by Daryle Walker, based on a work-around by Luc Danton
      85             : 
      86             : template < typename T, typename U >
      87             : struct is_related
      88             :     : public ::boost::is_same<
      89             :      typename ::boost::detail::remove_cv_ref<T>::type,
      90             :      typename ::boost::detail::remove_cv_ref<U>::type >
      91             : {};
      92             : 
      93             : //  Enable-if-on-unidentical-unmarked-type class template  -------------------//
      94             : 
      95             : // Enable-if on the first two type expressions NOT having the same raw type.
      96             : 
      97             : // Contributed by Daryle Walker, based on a work-around by Luc Danton
      98             : 
      99             : #ifndef BOOST_NO_CXX11_VARIADIC_TEMPLATES
     100             : template<typename ...T>
     101             : struct enable_if_unrelated
     102             :     : public ::boost::enable_if_c<true>
     103             : {};
     104             : 
     105             : template<typename T, typename U, typename ...U2>
     106             : struct enable_if_unrelated<T, U, U2...>
     107             :     : public ::boost::disable_if< ::boost::detail::is_related<T, U> >
     108             : {};
     109             : #endif
     110             : 
     111             : }  // namespace boost::detail
     112             : 
     113             : 
     114             : //  Base-from-member class template  -----------------------------------------//
     115             : 
     116             : // Helper to initialize a base object so a derived class can use this
     117             : // object in the initialization of another base class.  Used by
     118             : // Dietmar Kuehl from ideas by Ron Klatcho to solve the problem of a
     119             : // base class needing to be initialized by a member.
     120             : 
     121             : // Contributed by Daryle Walker
     122             : 
     123             : template < typename MemberType, int UniqueID = 0 >
     124           0 : class base_from_member
     125             : {
     126             : protected:
     127             :     MemberType  member;
     128             : 
     129             : #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && \
     130             :     !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && \
     131             :     !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) && \
     132             :     !(defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 4))
     133             :     template <typename ...T, typename EnableIf = typename
     134             :      ::boost::detail::enable_if_unrelated<base_from_member, T...>::type>
     135           0 :     explicit BOOST_CONSTEXPR base_from_member( T&& ...x )
     136             :         BOOST_NOEXCEPT_IF( BOOST_NOEXCEPT_EXPR(::new ((void*) 0) MemberType(
     137             :          static_cast<T&&>(x)... )) )  // no std::is_nothrow_constructible...
     138           0 :         : member( static_cast<T&&>(x)... )     // ...nor std::forward needed
     139           0 :         {}
     140             : #else
     141             :     base_from_member()
     142             :         : member()
     143             :         {}
     144             : 
     145             :     template < typename T0 > explicit base_from_member( T0 x0 ) : member( x0 ) {}
     146             :     BOOST_PP_REPEAT_FROM_TO( 2, BOOST_PP_INC(BOOST_BASE_FROM_MEMBER_MAX_ARITY),
     147             :      BOOST_PRIVATE_CTR_DEF, _ )
     148             : #endif
     149             : 
     150             : };  // boost::base_from_member
     151             : 
     152             : template < typename MemberType, int UniqueID >
     153             : class base_from_member<MemberType&, UniqueID>
     154             : {
     155             : protected:
     156             :     MemberType& member;
     157             : 
     158             :     explicit BOOST_CONSTEXPR base_from_member( MemberType& x )
     159             :         BOOST_NOEXCEPT
     160             :         : member( x )
     161             :         {}
     162             : 
     163             : };  // boost::base_from_member
     164             : 
     165             : }  // namespace boost
     166             : 
     167             : 
     168             : // Undo any private macros
     169             : #undef BOOST_PRIVATE_CTR_DEF
     170             : 
     171             : 
     172             : #endif  // BOOST_UTILITY_BASE_FROM_MEMBER_HPP