1/*=============================================================================
2 Copyright (c) 2001-2011 Joel de Guzman
3
4 Distributed under the Boost Software License, Version 1.0. (See accompanying
5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6==============================================================================*/
7#if !defined(FUSION_BEGIN_04052005_1132)
8#define FUSION_BEGIN_04052005_1132
9
10#include <boost/fusion/support/config.hpp>
11#include <boost/utility/enable_if.hpp>
12#include <boost/mpl/empty_base.hpp>
13#include <boost/mpl/if.hpp>
14#include <boost/fusion/sequence/intrinsic_fwd.hpp>
15#include <boost/fusion/support/tag_of.hpp>
16#include <boost/fusion/support/is_sequence.hpp>
17#include <boost/fusion/support/is_segmented.hpp>
18#include <boost/fusion/sequence/intrinsic/detail/segmented_begin.hpp>
19
20namespace boost { namespace fusion
21{
22 // Special tags:
23 struct sequence_facade_tag; // iterator facade tag
24 struct boost_tuple_tag; // boost::tuples::tuple tag
25 struct boost_array_tag; // boost::array tag
26 struct mpl_sequence_tag; // mpl sequence tag
27 struct std_pair_tag; // std::pair tag
28
29 namespace extension
30 {
31 template <typename Tag>
32 struct begin_impl
33 {
34 template <typename Sequence>
35 struct apply
36 : mpl::if_<
37 traits::is_segmented<Sequence>
38 , detail::segmented_begin<Sequence>
39 , mpl::empty_base
40 >::type
41 {};
42 };
43
44 template <>
45 struct begin_impl<sequence_facade_tag>
46 {
47 template <typename Sequence>
48 struct apply : Sequence::template begin<Sequence> {};
49 };
50
51 template <>
52 struct begin_impl<boost_tuple_tag>;
53
54 template <>
55 struct begin_impl<boost_array_tag>;
56
57 template <>
58 struct begin_impl<mpl_sequence_tag>;
59
60 template <>
61 struct begin_impl<std_pair_tag>;
62 }
63
64 namespace result_of
65 {
66 template <typename Sequence>
67 struct begin
68 : extension::begin_impl<typename detail::tag_of<Sequence>::type>::
69 template apply<Sequence>
70 {};
71 }
72
73 template <typename Sequence>
74 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
75 inline typename
76 lazy_enable_if<
77 traits::is_sequence<Sequence>
78 , result_of::begin<Sequence>
79 >::type const
80 begin(Sequence& seq)
81 {
82 return result_of::begin<Sequence>::call(seq);
83 }
84
85 template <typename Sequence>
86 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
87 inline typename
88 lazy_enable_if<
89 traits::is_sequence<Sequence>
90 , result_of::begin<Sequence const>
91 >::type const
92 begin(Sequence const& seq)
93 {
94 return result_of::begin<Sequence const>::call(seq);
95 }
96}}
97
98#endif
99

source code of include/boost/fusion/sequence/intrinsic/begin.hpp