hana/example/cppcon_2014/matrix/ring.hpp
2017-01-07 14:14:18 -08:00

63 lines
2.2 KiB
C++

// Copyright Louis Dionne 2013-2017
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#ifndef BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_RING_HPP
#define BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_RING_HPP
#include "matrix.hpp"
#include <boost/hana/equal.hpp>
#include <boost/hana/fwd/mult.hpp>
#include <boost/hana/fwd/one.hpp>
#include <boost/hana/if.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/range.hpp>
#include <boost/hana/replicate.hpp>
#include <boost/hana/transform.hpp>
#include <boost/hana/tuple.hpp>
#include <boost/hana/unpack.hpp>
#include <boost/hana/zip_with.hpp>
#include <utility>
namespace boost { namespace hana {
template <unsigned R1, unsigned C1, unsigned R2, unsigned C2>
struct mult_impl<cppcon::Matrix<R1, C1>, cppcon::Matrix<R2, C2>> {
template <typename M1, typename M2>
static constexpr decltype(auto) apply(M1&& m1, M2&& m2) {
static_assert(C1 == R2,
"wrong dimensions for matrix multiplication");
auto cols = cppcon::columns(std::forward<M2>(m2));
return unpack(
transform(cppcon::rows(std::forward<M1>(m1)),
[&](auto&& row) -> decltype(auto) {
return zip_with(cppcon::detail::tuple_scalar_product,
replicate<tuple_tag>(std::forward<decltype(row)>(row), uint_c<R1>),
cols
);
}
),
cppcon::matrix
);
}
};
template <unsigned R, unsigned C>
struct one_impl<cppcon::Matrix<R, C>> {
static constexpr decltype(auto) apply() {
return unpack(range_c<unsigned, 0, R>, [](auto ...n) {
return unpack(range_c<unsigned, 0, C>, [=](auto ...m) {
auto row = [=](auto n) {
return cppcon::row(if_(n == m, int_c<1>, int_c<0>)...);
};
return cppcon::matrix(row(n)...);
});
});
}
};
}}
#endif // !BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_RING_HPP