forked from boostorg/fusion
c2abefbab8
This allows to use, e.g., boost::fusion::fold within constexpr functions. The BOOST_CONSTEXPR macro is used to declare functions constexpr.
80 lines
2.3 KiB
C++
80 lines
2.3 KiB
C++
/*=============================================================================
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Copyright (c) 2006 Eric Niebler
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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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#if !defined(BOOST_FUSION_SEGMENTS_04052005_1141)
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#define BOOST_FUSION_SEGMENTS_04052005_1141
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#include <boost/fusion/support/config.hpp>
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#include <boost/type_traits/is_const.hpp>
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#include <boost/utility/enable_if.hpp>
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#include <boost/fusion/sequence/intrinsic_fwd.hpp>
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#include <boost/fusion/support/tag_of.hpp>
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namespace boost { namespace fusion
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{
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// Special tags:
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struct sequence_facade_tag;
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struct iterator_range_tag;
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// segments: returns a sequence of sequences
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namespace extension
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{
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template <typename Tag>
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struct segments_impl
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{
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template <typename Sequence>
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struct apply {};
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};
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template <>
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struct segments_impl<sequence_facade_tag>
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{
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template <typename Sequence>
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struct apply : Sequence::template segments<Sequence> {};
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};
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template <>
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struct segments_impl<iterator_range_tag>;
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}
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namespace result_of
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{
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template <typename Sequence>
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struct segments
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{
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typedef typename traits::tag_of<Sequence>::type tag_type;
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typedef typename
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extension::segments_impl<tag_type>::template apply<Sequence>::type
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type;
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};
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}
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template <typename Sequence>
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BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
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inline typename
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lazy_disable_if<
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is_const<Sequence>
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, result_of::segments<Sequence>
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>::type
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segments(Sequence& seq)
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{
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typedef typename traits::tag_of<Sequence>::type tag_type;
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return extension::segments_impl<tag_type>::template apply<Sequence>::call(seq);
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}
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template <typename Sequence>
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BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
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inline typename result_of::segments<Sequence const>::type
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segments(Sequence const& seq)
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{
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typedef typename traits::tag_of<Sequence const>::type tag_type;
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return extension::segments_impl<tag_type>::template apply<Sequence const>::call(seq);
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}
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}}
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#endif
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