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// $Id$
14// $Date$
15// $Revision$
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
31namespace boost { namespace mpl {
32
33// default implementation for forward/bidirectional iterators
34template< 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
63template<
64 typename BOOST_MPL_AUX_NA_PARAM(First)
65 , typename BOOST_MPL_AUX_NA_PARAM(Last)
66 >
67struct 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
74BOOST_MPL_AUX_NA_SPEC(2, distance)
75
76}}
77
78#endif // BOOST_MPL_DISTANCE_HPP_INCLUDED
79

source code of include/boost/mpl/distance.hpp