ceph/src/boost/libs/fusion/include/boost/fusion/iterator/detail/distance.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_DISTANCE_09172005_0730)
   8 #define FUSION_DISTANCE_09172005_0730
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/mpl/int.hpp>
  12 #include <boost/mpl/if.hpp>
  13 #include <boost/mpl/eval_if.hpp>
  14 #include <boost/mpl/next.hpp>
  15 #include <boost/mpl/identity.hpp>
  16 #include <boost/fusion/iterator/next.hpp>
  17 #include <boost/fusion/iterator/equal_to.hpp>
  18
  19 namespace boost { namespace fusion { namespace distance_detail
  20 {
  21     // Default distance implementation, linear
  22     // search for the Last iterator.
  23
  24     template <typename First, typename Last>
  25     struct linear_distance;
  26
  27     template <typename First, typename Last>
  28     struct next_distance
  29     {
  30         typedef typename
  31             mpl::next<
  32                 typename linear_distance<
  33                     typename result_of::next<First>::type
  34                   , Last
  35                 >::type
  36             >::type
  37         type;
  38     };
  39
  40     template <typename First, typename Last>
  41     struct linear_distance
  42         : mpl::eval_if<
  43             result_of::equal_to<First, Last>
  44           , mpl::identity<mpl::int_<0> >
  45           , next_distance<First, Last>
  46         >::type
  47     {
  48         typedef typename
  49             mpl::eval_if<
  50                 result_of::equal_to<First, Last>
  51               , mpl::identity<mpl::int_<0> >
  52               , next_distance<First, Last>
  53             >::type
  54         type;
  55
  56         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  57         static type
  58         call(First const&, Last const&)
  59         {
  60             return type();
  61         }
  62     };
  63
  64 }}}
  65
  66 #endif