129 lines
4.3 KiB
C++
Executable File
129 lines
4.3 KiB
C++
Executable File
/*=============================================================================
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Copyright (c) 2001-2007 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef BOOST_PP_IS_ITERATING
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#if !defined(BOOST_SPIRIT_AS_VARIANT_NOV_16_2007_0420PM)
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#define BOOST_SPIRIT_AS_VARIANT_NOV_16_2007_0420PM
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#include <boost/preprocessor/iterate.hpp>
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#include <boost/preprocessor/repetition/enum_params.hpp>
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#include <boost/preprocessor/repetition/enum_binary_params.hpp>
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#include <boost/preprocessor/repetition/enum_params_with_a_default.hpp>
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#include <boost/preprocessor/repetition/repeat_from_to.hpp>
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#include <boost/variant/variant_fwd.hpp>
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#include <boost/mpl/fold.hpp>
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#include <boost/mpl/vector.hpp>
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#include <boost/mpl/push_back.hpp>
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#include <boost/mpl/contains.hpp>
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#include <boost/type_traits/is_same.hpp>
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namespace boost { namespace spirit { namespace detail
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{
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template <int size>
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struct as_variant;
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template <>
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struct as_variant<0>
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{
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template <typename Iterator>
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struct apply
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{
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typedef variant<> type;
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};
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};
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#define BOOST_FUSION_NEXT_ITERATOR(z, n, data) \
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typedef typename fusion::result_of::next<BOOST_PP_CAT(I, n)>::type \
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BOOST_PP_CAT(I, BOOST_PP_INC(n));
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#define BOOST_FUSION_NEXT_CALL_ITERATOR(z, n, data) \
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typename gen::BOOST_PP_CAT(I, BOOST_PP_INC(n)) \
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BOOST_PP_CAT(i, BOOST_PP_INC(n)) = fusion::next(BOOST_PP_CAT(i, n));
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#define BOOST_FUSION_VALUE_OF_ITERATOR(z, n, data) \
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typedef typename fusion::result_of::value_of<BOOST_PP_CAT(I, n)>::type \
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BOOST_PP_CAT(T, n);
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#define BOOST_PP_FILENAME_1 <boost/spirit/home/support/as_variant.hpp>
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#define BOOST_PP_ITERATION_LIMITS (1, BOOST_VARIANT_LIMIT_TYPES)
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#include BOOST_PP_ITERATE()
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#undef BOOST_FUSION_NEXT_ITERATOR
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#undef BOOST_FUSION_NEXT_CALL_ITERATOR
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#undef BOOST_FUSION_VALUE_OF_ITERATOR
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template <typename Sequence>
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struct generate_variant
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{
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// build a variant generator being able to generate a variant holding
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// all of the types as given in the typelist
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typedef typename
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detail::as_variant<fusion::result_of::size<Sequence>::value>
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gen;
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// use this generator to create the actual variant
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typedef typename gen::template apply<
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typename fusion::result_of::begin<Sequence>::type
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>::type
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type;
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};
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}}}
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namespace boost { namespace spirit
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{
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template <typename Sequence>
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struct as_variant
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{
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// make sure each of the types occurs only once in the type list
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typedef typename
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mpl::fold<
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Sequence, mpl::vector<>,
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mpl::if_<
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mpl::contains<mpl::_1, mpl::_2>,
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mpl::_1, mpl::push_back<mpl::_1, mpl::_2>
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>
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>::type
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new_sequence;
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// if there is only one type in the list of types we strip off the
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// variant all together
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typedef typename
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mpl::eval_if<
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mpl::equal_to<mpl::size<new_sequence>, mpl::int_<1> >,
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mpl::deref<mpl::front<Sequence> >,
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detail::generate_variant<new_sequence>
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>::type
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type;
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};
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}}
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#endif
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#else // defined(BOOST_PP_IS_ITERATING)
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///////////////////////////////////////////////////////////////////////////////
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//
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// Preprocessor vertical repetition code
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//
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///////////////////////////////////////////////////////////////////////////////
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#define N BOOST_PP_ITERATION()
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template <>
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struct as_variant<N>
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{
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template <typename I0>
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struct apply
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{
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BOOST_PP_REPEAT(N, BOOST_FUSION_NEXT_ITERATOR, _)
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BOOST_PP_REPEAT(N, BOOST_FUSION_VALUE_OF_ITERATOR, _)
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typedef variant<BOOST_PP_ENUM_PARAMS(N, T)> type;
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};
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};
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#undef N
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#endif // defined(BOOST_PP_IS_ITERATING)
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