copy_n.hpp

#ifndef PASTELSYS_COPY_N_HPP
#define PASTELSYS_COPY_N_HPP

#include "pastel/sys/sequence/copy_n.h"

#include <boost/mpl/if.hpp>

#include <algorithm>
#include <iterator>
#include <type_traits>

namespace Pastel
{

    namespace CopyN_
    {

        class RandomAccess_Version
        {
        public:
            template <typename Source_ForwardIterator,
            typename Target_ForwardIterator>
            static void work(
                const Source_ForwardIterator& sourceBegin,
                integer count,
                const Target_ForwardIterator& targetBegin)
            {
                std::copy(sourceBegin, sourceBegin + count, targetBegin);
            }
        };

        class General_Version
        {
        public:
            template <typename Source_ForwardIterator,
            typename Target_ForwardIterator>
            static void work(
                Source_ForwardIterator sourceBegin,
                integer count,
                Target_ForwardIterator targetBegin)
            {
                for (integer i = 0;i < count;++i)
                {
                    *targetBegin = *sourceBegin;
                    ++targetBegin;
                    ++sourceBegin;
                }
            }
        };

    }

    template <typename Source_ForwardIterator,
    typename Target_ForwardIterator>
    void copy_n(
        const Source_ForwardIterator& sourceBegin,
        integer count,
        const Target_ForwardIterator& targetBegin)
    {
        ENSURE_OP(count, >=, 0);

        typedef typename boost::mpl::if_<
            std::is_same<
            typename std::iterator_traits<Source_ForwardIterator>::iterator_category,
            std::random_access_iterator_tag>,
            CopyN_::RandomAccess_Version,
            CopyN_::General_Version>::type Copy_n;

        Copy_n::work(sourceBegin, count, targetBegin);
    }

}

#endif