boost/mpl/distance.hpp

0001
0002 #ifndef BOOST_MPL_DISTANCE_HPP_INCLUDED
0003 #define BOOST_MPL_DISTANCE_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2000-2004
0006 //
0007 // Distributed under the Boost Software License, Version 1.0.
0008 // (See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // See http://www.boost.org/libs/mpl for documentation.
0012
0013 // $Id$
0014 // $Date$
0015 // $Revision$
0016
0017 #include <boost/mpl/distance_fwd.hpp>
0018 #include <boost/mpl/iter_fold.hpp>
0019 #include <boost/mpl/iterator_range.hpp>
0020 #include <boost/mpl/long.hpp>
0021 #include <boost/mpl/next.hpp>
0022 #include <boost/mpl/tag.hpp>
0023 #include <boost/mpl/apply_wrap.hpp>
0024 #include <boost/mpl/aux_/msvc_eti_base.hpp>
0025 #include <boost/mpl/aux_/value_wknd.hpp>
0026 #include <boost/mpl/aux_/na_spec.hpp>
0027 #include <boost/mpl/aux_/config/forwarding.hpp>
0028 #include <boost/mpl/aux_/config/static_constant.hpp>
0029
0030
0031 namespace boost { namespace mpl {
0032
0033 // default implementation for forward/bidirectional iterators
0034 template< typename Tag > struct distance_impl
0035 {
0036     template< typename First, typename Last > struct apply
0037 #if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
0038         : aux::msvc_eti_base< typename iter_fold<
0039               iterator_range<First,Last>
0040             , mpl::long_<0>
0041             , next<>
0042             >::type >
0043     {
0044 #else
0045     {
0046         typedef typename iter_fold<
0047               iterator_range<First,Last>
0048             , mpl::long_<0>
0049             , next<>
0050             >::type type;
0051
0052         BOOST_STATIC_CONSTANT(long, value =
0053               (iter_fold<
0054                   iterator_range<First,Last>
0055                 , mpl::long_<0>
0056                 , next<>
0057                 >::type::value)
0058             );
0059 #endif
0060     };
0061 };
0062
0063 template<
0064       typename BOOST_MPL_AUX_NA_PARAM(First)
0065     , typename BOOST_MPL_AUX_NA_PARAM(Last)
0066     >
0067 struct distance
0068     : distance_impl< typename tag<First>::type >
0069         ::template apply<First, Last>
0070 {
0071     BOOST_MPL_AUX_LAMBDA_SUPPORT(2, distance, (First, Last))
0072 };
0073
0074 BOOST_MPL_AUX_NA_SPEC(2, distance)
0075
0076 }}
0077
0078 #endif // BOOST_MPL_DISTANCE_HPP_INCLUDED