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      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: 2008-10-10 23:19:02 -0700 (Fri, 10 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
     79