| //----------------------------------------------------------------------------- |
| // boost variant/detail/visitation_impl.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_VISITATION_IMPL_HPP |
| #define BOOST_VARIANT_DETAIL_VISITATION_IMPL_HPP |
| |
| #include "boost/config.hpp" |
| |
| #include "boost/variant/detail/backup_holder.hpp" |
| #include "boost/variant/detail/cast_storage.hpp" |
| #include "boost/variant/detail/forced_return.hpp" |
| #include "boost/variant/detail/generic_result_type.hpp" |
| |
| #include "boost/assert.hpp" |
| #include "boost/mpl/eval_if.hpp" |
| #include "boost/mpl/bool.hpp" |
| #include "boost/mpl/identity.hpp" |
| #include "boost/mpl/int.hpp" |
| #include "boost/mpl/next.hpp" |
| #include "boost/mpl/deref.hpp" |
| #include "boost/mpl/or.hpp" |
| #include "boost/preprocessor/cat.hpp" |
| #include "boost/preprocessor/inc.hpp" |
| #include "boost/preprocessor/repeat.hpp" |
| #include "boost/type_traits/is_same.hpp" |
| #include "boost/type_traits/has_nothrow_copy.hpp" |
| #include "boost/variant/detail/has_nothrow_move.hpp" |
| |
| #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| # pragma warning (push) |
| # pragma warning (disable : 4702) //unreachable code |
| #endif |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // BOOST_VARIANT_VISITATION_UNROLLING_LIMIT |
| // |
| // Unrolls variant's visitation mechanism to reduce template instantiation |
| // and potentially increase runtime performance. (TODO: Investigate further.) |
| // |
| #if !defined(BOOST_VARIANT_VISITATION_UNROLLING_LIMIT) |
| # define BOOST_VARIANT_VISITATION_UNROLLING_LIMIT \ |
| BOOST_VARIANT_LIMIT_TYPES |
| #endif |
| |
| namespace boost { |
| namespace detail { namespace variant { |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // (detail) class apply_visitor_unrolled |
| // |
| // Tag type indicates when visitation_impl is unrolled. |
| // |
| struct apply_visitor_unrolled {}; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // (detail) class template visitation_impl_step |
| // |
| // "Never ending" iterator range facilitates visitation_impl unrolling. |
| // |
| |
| #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
| |
| template <typename Iter, typename LastIter> |
| struct visitation_impl_step |
| { |
| typedef typename mpl::deref<Iter>::type type; |
| |
| typedef typename mpl::next<Iter>::type next_iter; |
| typedef visitation_impl_step< |
| next_iter, LastIter |
| > next; |
| }; |
| |
| template <typename LastIter> |
| struct visitation_impl_step< LastIter,LastIter > |
| { |
| typedef apply_visitor_unrolled type; |
| typedef visitation_impl_step next; |
| }; |
| |
| #else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
| |
| template <typename Iter, typename LastIter> |
| struct visitation_impl_step |
| { |
| typedef typename mpl::eval_if< |
| is_same<Iter, LastIter> |
| , mpl::identity<apply_visitor_unrolled> |
| , Iter |
| >::type type; |
| |
| typedef typename mpl::eval_if< |
| is_same<type, apply_visitor_unrolled> //is_same<Iter, LastIter> |
| , mpl::identity<LastIter> |
| , mpl::next<Iter> |
| >::type next_iter; |
| |
| typedef visitation_impl_step< |
| next_iter, LastIter |
| > next; |
| }; |
| |
| #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // (detail) function template visitation_impl_invoke |
| // |
| // Invokes the given visitor on the specified type in the given storage. |
| // |
| |
| template <typename Visitor, typename VoidPtrCV, typename T> |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl_invoke_impl( |
| int, Visitor& visitor, VoidPtrCV storage, T* |
| , mpl::true_// never_uses_backup |
| ) |
| { |
| return visitor.internal_visit( |
| cast_storage<T>(storage), 1L |
| ); |
| } |
| |
| template <typename Visitor, typename VoidPtrCV, typename T> |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl_invoke_impl( |
| int internal_which, Visitor& visitor, VoidPtrCV storage, T* |
| , mpl::false_// never_uses_backup |
| ) |
| { |
| if (internal_which >= 0) |
| { |
| return visitor.internal_visit( |
| cast_storage<T>(storage), 1L |
| ); |
| } |
| else |
| { |
| return visitor.internal_visit( |
| cast_storage< backup_holder<T> >(storage), 1L |
| ); |
| } |
| } |
| |
| template <typename Visitor, typename VoidPtrCV, typename T, typename NoBackupFlag> |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl_invoke( |
| int internal_which, Visitor& visitor, VoidPtrCV storage, T* t |
| , NoBackupFlag |
| , int |
| ) |
| { |
| typedef typename mpl::or_< |
| NoBackupFlag |
| , has_nothrow_move_constructor<T> |
| , has_nothrow_copy<T> |
| >::type never_uses_backup; |
| |
| return visitation_impl_invoke_impl( |
| internal_which, visitor, storage, t |
| , never_uses_backup() |
| ); |
| } |
| |
| template <typename Visitor, typename VoidPtrCV, typename NBF> |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl_invoke(int, Visitor&, VoidPtrCV, apply_visitor_unrolled*, NBF, long) |
| { |
| // should never be here at runtime: |
| BOOST_ASSERT(false); |
| typedef typename Visitor::result_type result_type; |
| return ::boost::detail::variant::forced_return< result_type >(); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // (detail) function template visitation_impl |
| // |
| // Invokes the given visitor on the type in the given variant storage. |
| // |
| |
| template < |
| typename W, typename S |
| , typename Visitor, typename VPCV |
| , typename NBF |
| > |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl( |
| int, int, Visitor&, VPCV |
| , mpl::true_ // is_apply_visitor_unrolled |
| , NBF, W* = 0, S* = 0 |
| ) |
| { |
| // should never be here at runtime: |
| BOOST_ASSERT(false); |
| typedef typename Visitor::result_type result_type; |
| return ::boost::detail::variant::forced_return< result_type >(); |
| } |
| |
| template < |
| typename Which, typename step0 |
| , typename Visitor, typename VoidPtrCV |
| , typename NoBackupFlag |
| > |
| inline |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(typename Visitor::result_type) |
| visitation_impl( |
| const int internal_which, const int logical_which |
| , Visitor& visitor, VoidPtrCV storage |
| , mpl::false_ // is_apply_visitor_unrolled |
| , NoBackupFlag no_backup_flag |
| , Which* = 0, step0* = 0 |
| ) |
| { |
| // Typedef apply_visitor_unrolled steps and associated types... |
| # define BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_TYPEDEF(z, N, _) \ |
| typedef typename BOOST_PP_CAT(step,N)::type BOOST_PP_CAT(T,N); \ |
| typedef typename BOOST_PP_CAT(step,N)::next \ |
| BOOST_PP_CAT(step, BOOST_PP_INC(N)); \ |
| /**/ |
| |
| BOOST_PP_REPEAT( |
| BOOST_VARIANT_VISITATION_UNROLLING_LIMIT |
| , BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_TYPEDEF |
| , _ |
| ) |
| |
| # undef BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_TYPEDEF |
| |
| // ...switch on the target which-index value... |
| switch (logical_which) |
| { |
| |
| // ...applying the appropriate case: |
| # define BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_CASE(z, N, _) \ |
| case (Which::value + (N)): \ |
| return visitation_impl_invoke( \ |
| internal_which, visitor, storage \ |
| , static_cast<BOOST_PP_CAT(T,N)*>(0) \ |
| , no_backup_flag, 1L \ |
| ); \ |
| /**/ |
| |
| BOOST_PP_REPEAT( |
| BOOST_VARIANT_VISITATION_UNROLLING_LIMIT |
| , BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_CASE |
| , _ |
| ) |
| |
| # undef BOOST_VARIANT_AUX_APPLY_VISITOR_STEP_CASE |
| |
| } |
| |
| // If not handled in this iteration, continue unrolling: |
| typedef mpl::int_< |
| Which::value + (BOOST_VARIANT_VISITATION_UNROLLING_LIMIT) |
| > next_which; |
| |
| typedef BOOST_PP_CAT(step, BOOST_VARIANT_VISITATION_UNROLLING_LIMIT) |
| next_step; |
| |
| typedef typename next_step::type next_type; |
| typedef typename is_same< next_type,apply_visitor_unrolled >::type |
| is_apply_visitor_unrolled; |
| |
| return visitation_impl( |
| internal_which, logical_which |
| , visitor, storage |
| , is_apply_visitor_unrolled() |
| , no_backup_flag |
| , static_cast<next_which*>(0), static_cast<next_step*>(0) |
| ); |
| } |
| |
| }} // namespace detail::variant |
| } // namespace boost |
| |
| #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) |
| # pragma warning(pop) |
| #endif |
| |
| #endif // BOOST_VARIANT_DETAIL_VISITATION_IMPL_HPP |