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