ceph/src/boost/libs/fusion/include/boost/fusion/iterator/mpl/convert_iterator.hpp

   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_CONVERT_ITERATOR_05062005_1218)
   8 #define FUSION_CONVERT_ITERATOR_05062005_1218
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/fusion/support/is_iterator.hpp>
  12 #include <boost/mpl/if.hpp>
  13 #include <boost/mpl/bool.hpp>
  14
  15 namespace boost { namespace fusion
  16 {
  17     template <typename Iterator>
  18     struct mpl_iterator; // forward declaration
  19
  20     //  Test T. If it is a fusion iterator, return a reference to it.
  21     //  else, assume it is an mpl iterator.
  22
  23     template <typename T>
  24     struct convert_iterator
  25     {
  26         typedef typename
  27             mpl::if_<
  28                 is_fusion_iterator<T>
  29               , T
  30               , mpl_iterator<T>
  31             >::type
  32         type;
  33
  34         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  35         static T const&
  36         call(T const& x, mpl::true_)
  37         {
  38             return x;
  39         }
  40
  41         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  42         static mpl_iterator<T>
  43         call(T const& /*x*/, mpl::false_)
  44         {
  45             return mpl_iterator<T>();
  46         }
  47
  48         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  49         static typename
  50             mpl::if_<
  51                 is_fusion_iterator<T>
  52               , T const&
  53               , mpl_iterator<T>
  54             >::type
  55         call(T const& x)
  56         {
  57             return call(x, is_fusion_iterator<T>());
  58         }
  59     };
  60 }}
  61
  62 #endif