| /*============================================================================= |
| Copyright (c) 2001-2007 Joel de Guzman |
| |
| 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_PP_IS_ITERATING |
| #if !defined(BOOST_SPIRIT_AS_VARIANT_NOV_16_2007_0420PM) |
| #define BOOST_SPIRIT_AS_VARIANT_NOV_16_2007_0420PM |
| |
| #include <boost/preprocessor/iterate.hpp> |
| #include <boost/preprocessor/repetition/enum_params.hpp> |
| #include <boost/preprocessor/repetition/enum_binary_params.hpp> |
| #include <boost/preprocessor/repetition/enum_params_with_a_default.hpp> |
| #include <boost/preprocessor/repetition/repeat_from_to.hpp> |
| #include <boost/variant/variant_fwd.hpp> |
| #include <boost/mpl/fold.hpp> |
| #include <boost/mpl/vector.hpp> |
| #include <boost/mpl/push_back.hpp> |
| #include <boost/mpl/contains.hpp> |
| #include <boost/type_traits/is_same.hpp> |
| |
| namespace boost { namespace spirit { namespace detail |
| { |
| template <int size> |
| struct as_variant; |
| |
| template <> |
| struct as_variant<0> |
| { |
| template <typename Iterator> |
| struct apply |
| { |
| typedef variant<> type; |
| }; |
| }; |
| |
| #define BOOST_FUSION_NEXT_ITERATOR(z, n, data) \ |
| typedef typename fusion::result_of::next<BOOST_PP_CAT(I, n)>::type \ |
| BOOST_PP_CAT(I, BOOST_PP_INC(n)); |
| |
| #define BOOST_FUSION_NEXT_CALL_ITERATOR(z, n, data) \ |
| typename gen::BOOST_PP_CAT(I, BOOST_PP_INC(n)) \ |
| BOOST_PP_CAT(i, BOOST_PP_INC(n)) = fusion::next(BOOST_PP_CAT(i, n)); |
| |
| #define BOOST_FUSION_VALUE_OF_ITERATOR(z, n, data) \ |
| typedef typename fusion::result_of::value_of<BOOST_PP_CAT(I, n)>::type \ |
| BOOST_PP_CAT(T, n); |
| |
| #define BOOST_PP_FILENAME_1 <boost/spirit/home/support/as_variant.hpp> |
| #define BOOST_PP_ITERATION_LIMITS (1, BOOST_VARIANT_LIMIT_TYPES) |
| #include BOOST_PP_ITERATE() |
| |
| #undef BOOST_FUSION_NEXT_ITERATOR |
| #undef BOOST_FUSION_NEXT_CALL_ITERATOR |
| #undef BOOST_FUSION_VALUE_OF_ITERATOR |
| |
| template <typename Sequence> |
| struct generate_variant |
| { |
| // build a variant generator being able to generate a variant holding |
| // all of the types as given in the typelist |
| typedef typename |
| detail::as_variant<fusion::result_of::size<Sequence>::value> |
| gen; |
| |
| // use this generator to create the actual variant |
| typedef typename gen::template apply< |
| typename fusion::result_of::begin<Sequence>::type |
| >::type |
| type; |
| }; |
| |
| }}} |
| |
| namespace boost { namespace spirit |
| { |
| template <typename Sequence> |
| struct as_variant |
| { |
| // make sure each of the types occurs only once in the type list |
| typedef typename |
| mpl::fold< |
| Sequence, mpl::vector<>, |
| mpl::if_< |
| mpl::contains<mpl::_1, mpl::_2>, |
| mpl::_1, mpl::push_back<mpl::_1, mpl::_2> |
| > |
| >::type |
| new_sequence; |
| |
| // if there is only one type in the list of types we strip off the |
| // variant all together |
| typedef typename |
| mpl::eval_if< |
| mpl::equal_to<mpl::size<new_sequence>, mpl::int_<1> >, |
| mpl::deref<mpl::front<Sequence> >, |
| detail::generate_variant<new_sequence> |
| >::type |
| type; |
| }; |
| }} |
| |
| #endif |
| #else // defined(BOOST_PP_IS_ITERATING) |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // Preprocessor vertical repetition code |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #define N BOOST_PP_ITERATION() |
| |
| template <> |
| struct as_variant<N> |
| { |
| template <typename I0> |
| struct apply |
| { |
| BOOST_PP_REPEAT(N, BOOST_FUSION_NEXT_ITERATOR, _) |
| BOOST_PP_REPEAT(N, BOOST_FUSION_VALUE_OF_ITERATOR, _) |
| typedef variant<BOOST_PP_ENUM_PARAMS(N, T)> type; |
| }; |
| }; |
| |
| #undef N |
| #endif // defined(BOOST_PP_IS_ITERATING) |
| |