variadic_sum.hpp

Go to the documentation of this file.

#ifndef BOOST_MPL11_DETAIL_COUNT_IF_VARIADIC_SUM_HPP
#define BOOST_MPL11_DETAIL_COUNT_IF_VARIADIC_SUM_HPP

#include <boost/mpl11/detail/std_size_t.hpp>
#include <boost/mpl11/integer.hpp>


namespace boost { namespace mpl11 { namespace detail { namespace count_if {
    template <std_size_t N>
    constexpr std_size_t homogeneous_sum(const bool (&array)[N]) {
        std_size_t s = 0;
        for (std_size_t i = 0; i < N; ++i)
            s += array[i];
        return s;
    }

    template <template <typename ...> class predicate, typename ...xs>
    using variadic_sum = size_t<
        // Avoid empty arrays
        homogeneous_sum<sizeof...(xs)+1>(
            {false, (bool)predicate<xs>::type::value...}
        )
    >;
}}}} // end namespace boost::mpl11::detail::count_if

#endif // !BOOST_MPL11_DETAIL_COUNT_IF_VARIADIC_SUM_HPP