williamr@2: //-----------------------------------------------------------------------------
williamr@2: // boost variant/detail/enable_recursive.hpp header file
williamr@2: // See http://www.boost.org for updates, documentation, and revision history.
williamr@2: //-----------------------------------------------------------------------------
williamr@2: //
williamr@2: // Copyright (c) 2003
williamr@2: // Eric Friedman
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: #ifndef BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
williamr@2: #define BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
williamr@2: 
williamr@2: #include "boost/variant/detail/enable_recursive_fwd.hpp"
williamr@2: #include "boost/variant/variant_fwd.hpp"
williamr@2: 
williamr@2: #if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)
williamr@2: #   include "boost/mpl/apply.hpp"
williamr@2: #   include "boost/mpl/eval_if.hpp"
williamr@2: #   include "boost/mpl/lambda.hpp"
williamr@2: #endif
williamr@2: 
williamr@2: #include "boost/variant/detail/substitute.hpp"
williamr@2: #include "boost/mpl/aux_/config/ctps.hpp"
williamr@2: #include "boost/mpl/bool_fwd.hpp"
williamr@2: #include "boost/mpl/if.hpp"
williamr@2: #include "boost/mpl/or.hpp"
williamr@2: #include "boost/type_traits/is_pointer.hpp"
williamr@2: #include "boost/type_traits/is_reference.hpp"
williamr@2: #include "boost/type_traits/is_same.hpp"
williamr@2: 
williamr@2: #include "boost/variant/recursive_wrapper.hpp"
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace detail { namespace variant {
williamr@2: 
williamr@2: #if !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
williamr@2: 
williamr@2: #   define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \
williamr@2:     substitute< T , Dest , Source > \
williamr@2:     /**/
williamr@2: 
williamr@2: #else // defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
williamr@2: 
williamr@2: ///////////////////////////////////////////////////////////////////////////////
williamr@2: // (detail) class template rebind1
williamr@2: //
williamr@2: // Limited workaround in case 'substitute' metafunction unavailable.
williamr@2: //
williamr@2: 
williamr@2: template <typename T, typename U1>
williamr@2: struct rebind1
williamr@2: {
williamr@2: private:
williamr@2:     typedef typename mpl::lambda<
williamr@2:           mpl::identity<T>
williamr@2:         >::type le_;
williamr@2: 
williamr@2: public:
williamr@2:     typedef typename mpl::eval_if<
williamr@2:           is_same< le_, mpl::identity<T> >
williamr@2:         , le_ // identity<T>
williamr@2:         , mpl::apply1<le_, U1>
williamr@2:         >::type type;
williamr@2: };
williamr@2: 
williamr@2: #   define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \
williamr@2:     rebind1< T , Dest > \
williamr@2:     /**/
williamr@2: 
williamr@2: #endif // !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
williamr@2: 
williamr@2: ///////////////////////////////////////////////////////////////////////////////
williamr@2: // (detail) metafunction enable_recursive
williamr@2: //
williamr@2: // See boost/variant/detail/enable_recursive_fwd.hpp for more information.
williamr@2: //
williamr@2: 
williamr@2: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
williamr@2: 
williamr@2: template <typename T, typename RecursiveVariant, typename NoWrapper>
williamr@2: struct enable_recursive
williamr@2:     : BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
williamr@2:           T, RecursiveVariant, ::boost::recursive_variant_
williamr@2:         )
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: template <typename T, typename RecursiveVariant>
williamr@2: struct enable_recursive< T,RecursiveVariant,mpl::false_ >
williamr@2: {
williamr@2: private: // helpers, for metafunction result (below)
williamr@2: 
williamr@2:     typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
williamr@2:           T, RecursiveVariant, ::boost::recursive_variant_
williamr@2:         )::type t_;
williamr@2: 
williamr@2: public: // metafunction result
williamr@2: 
williamr@2:     // [Wrap with recursive_wrapper only if rebind really changed something:]
williamr@2:     typedef typename mpl::if_<
williamr@2:           mpl::or_<
williamr@2:               is_same< t_,T >
williamr@2:             , is_reference<t_>
williamr@2:             , is_pointer<t_>
williamr@2:             >
williamr@2:         , t_
williamr@2:         , boost::recursive_wrapper<t_>
williamr@2:         >::type type;
williamr@2: 
williamr@2: };
williamr@2: 
williamr@2: #else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
williamr@2: 
williamr@2: template <typename T, typename RecursiveVariant, typename NoWrapper>
williamr@2: struct enable_recursive
williamr@2: {
williamr@2: private: // helpers, for metafunction result (below)
williamr@2: 
williamr@2:     typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
williamr@2:           T, RecursiveVariant, ::boost::recursive_variant_
williamr@2:         )::type t_;
williamr@2: 
williamr@2: public: // metafunction result
williamr@2: 
williamr@2:     // [Wrap with recursive_wrapper only if rebind really changed something:]
williamr@2:     typedef typename mpl::if_<
williamr@2:           mpl::or_<
williamr@2:               NoWrapper
williamr@2:             , is_same< t_,T >
williamr@2:             , is_reference<t_>
williamr@2:             , is_pointer<t_>
williamr@2:             >
williamr@2:         , t_
williamr@2:         , boost::recursive_wrapper<t_>
williamr@2:         >::type type;
williamr@2: 
williamr@2: };
williamr@2: 
williamr@2: #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround
williamr@2: 
williamr@2: ///////////////////////////////////////////////////////////////////////////////
williamr@2: // (detail) metafunction class quoted_enable_recursive
williamr@2: //
williamr@2: // Same behavior as enable_recursive metafunction (see above).
williamr@2: //
williamr@2: template <typename RecursiveVariant, typename NoWrapper>
williamr@2: struct quoted_enable_recursive
williamr@2: {
williamr@2:     template <typename T>
williamr@2:     struct apply
williamr@2:         : enable_recursive<T, RecursiveVariant, NoWrapper>
williamr@2:     {
williamr@2:     };
williamr@2: };
williamr@2: 
williamr@2: }} // namespace detail::variant
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP