Chris@16: //-----------------------------------------------------------------------------
Chris@16: // boost variant/recursive_variant.hpp header file
Chris@16: // See http://www.boost.org for updates, documentation, and revision history.
Chris@16: //-----------------------------------------------------------------------------
Chris@16: //
Chris@101: // Copyright (c) 2003 Eric Friedman
Chris@101: // Copyright (c) 2013 Antony Polukhin
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_VARIANT_RECURSIVE_VARIANT_HPP
Chris@16: #define BOOST_VARIANT_RECURSIVE_VARIANT_HPP
Chris@16: 
Chris@16: #include "boost/variant/variant_fwd.hpp"
Chris@16: #include "boost/variant/detail/enable_recursive.hpp"
Chris@16: #include "boost/variant/detail/substitute_fwd.hpp"
Chris@16: #include "boost/variant/detail/make_variant_list.hpp"
Chris@16: #include "boost/variant/detail/over_sequence.hpp"
Chris@16: 
Chris@16: #include "boost/mpl/aux_/lambda_arity_param.hpp"
Chris@16: 
Chris@16: #include "boost/mpl/equal.hpp"
Chris@16: #include "boost/mpl/eval_if.hpp"
Chris@16: #include "boost/mpl/identity.hpp"
Chris@16: #include "boost/mpl/if.hpp"
Chris@16: #include "boost/mpl/protect.hpp"
Chris@16: #include "boost/mpl/transform.hpp"
Chris@16: #include "boost/type_traits/is_same.hpp"
Chris@16: #include "boost/preprocessor/cat.hpp"
Chris@16: #include "boost/preprocessor/repeat.hpp"
Chris@16: 
Chris@16: #include "boost/mpl/bool.hpp"
Chris@16: #include "boost/mpl/is_sequence.hpp"
Chris@16: #include "boost/variant/variant.hpp"
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: namespace detail { namespace variant {
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // (detail) metafunction specialization substitute
Chris@16: //
Chris@16: // Handles embedded variant types when substituting for recursive_variant_.
Chris@16: //
Chris@16: 
Chris@16: #if !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
Chris@16: 
Chris@16: template <
Chris@16:       BOOST_VARIANT_ENUM_PARAMS(typename T)
Chris@16:     , typename RecursiveVariant
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity)
Chris@16:     >
Chris@16: struct substitute<
Chris@16:       ::boost::variant<
Chris@16:           recursive_flag< T0 >
Chris@16:         , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
Chris@16:         >
Chris@16:     , RecursiveVariant
Chris@16:     , ::boost::recursive_variant_
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity)
Chris@16:     >
Chris@16: {
Chris@16:     typedef ::boost::variant<
Chris@16:           recursive_flag< T0 >
Chris@16:         , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
Chris@16:         > type;
Chris@16: };
Chris@16: 
Chris@16: template <
Chris@16:       BOOST_VARIANT_ENUM_PARAMS(typename T)
Chris@16:     , typename RecursiveVariant
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity)
Chris@16:     >
Chris@16: struct substitute<
Chris@16:       ::boost::variant<
Chris@16:           ::boost::detail::variant::over_sequence< T0 >
Chris@16:         , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
Chris@16:         >
Chris@16:     , RecursiveVariant
Chris@16:     , ::boost::recursive_variant_
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity)
Chris@16:     >
Chris@16: {
Chris@16: private:
Chris@16: 
Chris@16:     typedef T0 initial_types;
Chris@16: 
Chris@16:     typedef typename mpl::transform<
Chris@16:           initial_types
Chris@16:         , mpl::protect< quoted_enable_recursive<RecursiveVariant,mpl::true_> >
Chris@16:         >::type types;
Chris@16: 
Chris@16: public:
Chris@16: 
Chris@16:     typedef typename mpl::if_<
Chris@16:           mpl::equal<initial_types, types, ::boost::is_same<mpl::_1, mpl::_2> >
Chris@16:         , ::boost::variant<
Chris@16:               ::boost::detail::variant::over_sequence< T0 >
Chris@16:             , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
Chris@16:             >
Chris@16:         , ::boost::variant< over_sequence<types> >
Chris@16:         >::type type;
Chris@16: };
Chris@16: 
Chris@16: template <
Chris@16:       BOOST_VARIANT_ENUM_PARAMS(typename T)
Chris@16:     , typename RecursiveVariant
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity)
Chris@16:     >
Chris@16: struct substitute<
Chris@16:       ::boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >
Chris@16:     , RecursiveVariant
Chris@16:     , ::boost::recursive_variant_
Chris@16:       BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity)
Chris@16:     >
Chris@16: {
Chris@101: #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101:     
Chris@101:     typedef ::boost::variant<
Chris@101:         typename enable_recursive<   
Chris@101:               T0              
Chris@101:             , RecursiveVariant               
Chris@101:             , mpl::true_                     
Chris@101:         >::type,
Chris@101:         typename enable_recursive<   
Chris@101:               TN              
Chris@101:             , RecursiveVariant               
Chris@101:             , mpl::true_                     
Chris@101:         >::type...  
Chris@101:     > type;
Chris@101: 
Chris@101: #else // defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101: 
Chris@16: private: // helpers, for metafunction result (below)
Chris@16: 
Chris@16:     #define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS(z,N,_)  \
Chris@16:         typedef typename enable_recursive<   \
Chris@16:               BOOST_PP_CAT(T,N)              \
Chris@16:             , RecursiveVariant               \
Chris@16:             , mpl::true_                     \
Chris@16:             >::type BOOST_PP_CAT(wknd_T,N);  \
Chris@16:         /**/
Chris@16: 
Chris@16:     BOOST_PP_REPEAT(
Chris@16:           BOOST_VARIANT_LIMIT_TYPES
Chris@16:         , BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
Chris@16:         , _
Chris@16:         )
Chris@16: 
Chris@16:     #undef BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
Chris@16: 
Chris@16: public: // metafunction result
Chris@16: 
Chris@16:     typedef ::boost::variant< BOOST_VARIANT_ENUM_PARAMS(wknd_T) > type;
Chris@101: #endif // BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES workaround
Chris@16: };
Chris@16: 
Chris@16: #else // defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
Chris@16: 
Chris@16: //
Chris@16: // no specializations: embedded variants unsupported on these compilers!
Chris@16: //
Chris@16: 
Chris@16: #endif // !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
Chris@16: 
Chris@16: }} // namespace detail::variant
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction make_recursive_variant
Chris@16: //
Chris@16: // See docs and boost/variant/variant_fwd.hpp for more information.
Chris@16: //
Chris@16: template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
Chris@16: struct make_recursive_variant
Chris@16: {
Chris@16: public: // metafunction result
Chris@16: 
Chris@16:     typedef boost::variant<
Chris@16:           detail::variant::recursive_flag< T0 >
Chris@16:         , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
Chris@16:         > type;
Chris@16: 
Chris@16: };
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction make_recursive_variant_over
Chris@16: //
Chris@16: // See docs and boost/variant/variant_fwd.hpp for more information.
Chris@16: //
Chris@16: template <typename Types>
Chris@16: struct make_recursive_variant_over
Chris@16: {
Chris@16: private: // precondition assertions
Chris@16: 
Chris@16:     BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value ));
Chris@16: 
Chris@16: public: // metafunction result
Chris@16: 
Chris@16:     typedef typename make_recursive_variant<
Chris@16:           detail::variant::over_sequence< Types >
Chris@16:         >::type type;
Chris@16: 
Chris@16: };
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_VARIANT_RECURSIVE_VARIANT_HPP