any.hpp

来自「Boost provides free peer-reviewed portab」· HPP 代码 · 共 131 行

/*=============================================================================
    Copyright (c) 2001-2006 Joel de Guzman
    Copyright (c) 2005 Eric Niebler
    Copyright (c) 2007 Dan Marsden

    Distributed under the Boost Software License, Version 1.0. (See accompanying 
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#if !defined(FUSION_ANY_05052005_1229)
#define FUSION_ANY_05052005_1229

#include <boost/mpl/bool.hpp>
#include <boost/fusion/sequence/intrinsic/begin.hpp>
#include <boost/fusion/sequence/intrinsic/end.hpp>
#include <boost/fusion/iterator/advance.hpp>
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/iterator/distance.hpp>

namespace boost { namespace fusion { 
    struct random_access_traversal_tag;
namespace detail
{
    template <typename First, typename Last, typename F>
    inline bool
    linear_any(First const&, Last const&, F const&, mpl::true_)
    {
        return false;
    }

    template <typename First, typename Last, typename F>
    inline bool
    linear_any(First const& first, Last const& last, F& f, mpl::false_)
    {
        typename result_of::deref<First>::type x = *first;
        return f(x) || 
            detail::linear_any(
                fusion::next(first)
              , last
              , f
              , result_of::equal_to<typename result_of::next<First>::type, Last>());
    }

    template <typename Sequence, typename F, typename Tag>
    inline bool
    any(Sequence const& seq, F f, Tag)
    {
        return detail::linear_any(
                fusion::begin(seq)
              , fusion::end(seq)
              , f
              , result_of::equal_to<
                    typename result_of::begin<Sequence>::type
                  , typename result_of::end<Sequence>::type>());
    }

    template<int N>
    struct unrolled_any
    {
        template <typename It, typename F>
        static bool call(It const& it, F f)
        {
            return 
                f(*it) || 
                f(*fusion::advance_c<1>(it))||
                f(*fusion::advance_c<2>(it)) ||
                f(*fusion::advance_c<3>(it)) ||
                detail::unrolled_any<N-4>::call(fusion::advance_c<4>(it), f);
        }
    };

    template<>
    struct unrolled_any<3>
    {
        template <typename It, typename F>
        static bool call(It const& it, F f)
        {
            return 
                f(*it) || 
                f(*fusion::advance_c<1>(it)) ||
                f(*fusion::advance_c<2>(it));
        }
    };

    template<>
    struct unrolled_any<2>
    {
        template <typename It, typename F>
        static bool call(It const& it, F f)
        {
            return 
                f(*it) || 
                f(*fusion::advance_c<1>(it));
        }
    };

    template<>
    struct unrolled_any<1>
    {
        template <typename It, typename F>
        static bool call(It const& it, F f)
        {
            return f(*it);
        }
    };

    template<>
    struct unrolled_any<0>
    {
        template <typename It, typename F>
        static bool call(It const& it, F f)
        {
            return false;
        }
    };

    template <typename Sequence, typename F>
    inline bool
    any(Sequence const& seq, F f, random_access_traversal_tag)
    {
        typedef typename result_of::begin<Sequence>::type begin;
        typedef typename result_of::end<Sequence>::type end;
        return detail::unrolled_any<result_of::distance<begin, end>::type::value>::call(
            fusion::begin(seq), f);
    }
}}}

#endif