boost/mpl/distance.hpp

   1
   2 #ifndef BOOST_MPL_DISTANCE_HPP_INCLUDED
   3 #define BOOST_MPL_DISTANCE_HPP_INCLUDED
   4
   5 // Copyright Aleksey Gurtovoy 2000-2004
   6 //
   7 // Distributed under the Boost Software License, Version 1.0.
   8 // (See accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11 // See http://www.boost.org/libs/mpl for documentation.
  12
  13 // $Id: distance.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
  14 // $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $
  15 // $Revision: 49267 $
  16
  17 #include <boost/mpl/distance_fwd.hpp>
  18 #include <boost/mpl/iter_fold.hpp>
  19 #include <boost/mpl/iterator_range.hpp>
  20 #include <boost/mpl/long.hpp>
  21 #include <boost/mpl/next.hpp>
  22 #include <boost/mpl/tag.hpp>
  23 #include <boost/mpl/apply_wrap.hpp>
  24 #include <boost/mpl/aux_/msvc_eti_base.hpp>
  25 #include <boost/mpl/aux_/value_wknd.hpp>
  26 #include <boost/mpl/aux_/na_spec.hpp>
  27 #include <boost/mpl/aux_/config/forwarding.hpp>
  28 #include <boost/mpl/aux_/config/static_constant.hpp>
  29
  30
  31 namespace boost { namespace mpl {
  32
  33 // default implementation for forward/bidirectional iterators
  34 template< typename Tag > struct distance_impl
  35 {
  36     template< typename First, typename Last > struct apply
  37 #if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
  38         : aux::msvc_eti_base< typename iter_fold<
  39               iterator_range<First,Last>
  40             , mpl::long_<0>
  41             , next<>
  42             >::type >
  43     {
  44 #else
  45     {
  46         typedef typename iter_fold<
  47               iterator_range<First,Last>
  48             , mpl::long_<0>
  49             , next<>
  50             >::type type;
  51
  52         BOOST_STATIC_CONSTANT(long, value =
  53               (iter_fold<
  54                   iterator_range<First,Last>
  55                 , mpl::long_<0>
  56                 , next<>
  57                 >::type::value)
  58             );
  59 #endif
  60     };
  61 };
  62
  63 template<
  64       typename BOOST_MPL_AUX_NA_PARAM(First)
  65     , typename BOOST_MPL_AUX_NA_PARAM(Last)
  66     >
  67 struct distance
  68     : distance_impl< typename tag<First>::type >
  69         ::template apply<First, Last>
  70 {
  71     BOOST_MPL_AUX_LAMBDA_SUPPORT(2, distance, (First, Last))
  72 };
  73
  74 BOOST_MPL_AUX_NA_SPEC(2, distance)
  75
  76 }}
  77
  78 #endif // BOOST_MPL_DISTANCE_HPP_INCLUDED