/Src/Dependencies/Boost/boost/fusion/sequence/intrinsic/at.hpp

  1/*=============================================================================
  2    Copyright (c) 2001-2006 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_AT_05042005_0722)
  8#define FUSION_AT_05042005_0722
  9
 10#include <boost/mpl/int.hpp>
 11#include <boost/type_traits/is_const.hpp>
 12#include <boost/fusion/support/tag_of.hpp>
 13#include <boost/fusion/support/detail/access.hpp>
 14
 15namespace boost { namespace fusion
 16{
 17    // Special tags:
 18    struct sequence_facade_tag;
 19    struct boost_tuple_tag; // boost::tuples::tuple tag
 20    struct boost_array_tag; // boost::array tag
 21    struct mpl_sequence_tag; // mpl sequence tag
 22    struct std_pair_tag; // std::pair tag
 23
 24    namespace extension
 25    {
 26        template <typename Tag>
 27        struct at_impl
 28        {
 29            template <typename Sequence, typename N>
 30            struct apply;
 31        };
 32
 33        template <>
 34        struct at_impl<sequence_facade_tag>
 35        {
 36            template <typename Sequence, typename N>
 37            struct apply : Sequence::template at<Sequence, N> {};
 38        };
 39
 40        template <>
 41        struct at_impl<boost_tuple_tag>;
 42
 43        template <>
 44        struct at_impl<boost_array_tag>;
 45
 46        template <>
 47        struct at_impl<mpl_sequence_tag>;
 48
 49        template <>
 50        struct at_impl<std_pair_tag>;
 51    }
 52
 53    namespace result_of
 54    {
 55        template <typename Sequence, typename N>
 56        struct at 
 57            : extension::at_impl<typename detail::tag_of<Sequence>::type>::
 58                template apply<Sequence, N>
 59        {};
 60
 61        template <typename Sequence, int N>
 62        struct at_c
 63            : at<Sequence, mpl::int_<N> >
 64        {};
 65    }
 66
 67
 68    template <typename N, typename Sequence>
 69    inline typename 
 70        lazy_disable_if<
 71            is_const<Sequence>
 72          , result_of::at<Sequence, N>
 73        >::type
 74    at(Sequence& seq)
 75    {
 76        return result_of::at<Sequence, N>::call(seq);
 77    }
 78
 79    template <typename N, typename Sequence>
 80    inline typename result_of::at<Sequence const, N>::type
 81    at(Sequence const& seq)
 82    {
 83        return result_of::at<Sequence const, N>::call(seq);
 84    }
 85
 86    template <int N, typename Sequence>
 87    inline typename 
 88        lazy_disable_if<
 89            is_const<Sequence>
 90          , result_of::at_c<Sequence, N>
 91        >::type
 92    at_c(Sequence& seq)
 93    {
 94        return fusion::at<mpl::int_<N> >(seq);
 95    }
 96
 97    template <int N, typename Sequence>
 98    inline typename result_of::at_c<Sequence const, N>::type
 99    at_c(Sequence const& seq)
100    {
101        return fusion::at<mpl::int_<N> >(seq);
102    }
103}}
104
105#endif
106