1 /*=============================================================================
2 Copyright (c) 2001-2011 Joel de Guzman
3 Copyright (c) 2006 Dan Marsden
5 Distributed under the Boost Software License, Version 1.0. (See accompanying
6 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7 ==============================================================================*/
8 #if !defined(FUSION_BEGIN_IMPL_20060123_2147)
9 #define FUSION_BEGIN_IMPL_20060123_2147
11 #include <boost/fusion/support/config.hpp>
12 #include <boost/fusion/sequence/intrinsic/begin.hpp>
13 #include <boost/fusion/view/zip_view/zip_view_iterator_fwd.hpp>
14 #include <boost/fusion/algorithm/transformation/transform.hpp>
15 #include <boost/type_traits/remove_reference.hpp>
16 #include <boost/type_traits/is_reference.hpp>
17 #include <boost/type_traits/is_same.hpp>
18 #include <boost/mpl/assert.hpp>
19 #include <boost/mpl/eval_if.hpp>
20 #include <boost/mpl/identity.hpp>
21 #include <boost/fusion/support/unused.hpp>
23 namespace boost { namespace fusion {
34 template<typename SeqRef>
35 struct result<poly_begin(SeqRef)>
36 : mpl::eval_if<is_same<SeqRef, unused_type const&>,
37 mpl::identity<unused_type>,
38 result_of::begin<typename remove_reference<SeqRef>::type> >
40 BOOST_MPL_ASSERT((is_reference<SeqRef>));
43 template<typename Seq>
44 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
45 typename result<poly_begin(Seq&)>::type
46 operator()(Seq& seq) const
48 return fusion::begin(seq);
51 template<typename Seq>
52 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
53 typename result<poly_begin(Seq const&)>::type
54 operator()(Seq const& seq) const
56 return fusion::begin(seq);
59 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
60 unused_type operator()(unused_type const&) const
69 template<typename Tag>
73 struct begin_impl<zip_view_tag>
75 template<typename Sequence>
78 typedef zip_view_iterator<
79 typename result_of::transform<typename Sequence::sequences, detail::poly_begin>::type,
80 typename Sequence::category> type;
82 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
84 call(Sequence& sequence)
87 fusion::transform(sequence.sequences_, detail::poly_begin()));