/*! @file Defines `boost::hana::fill`. @copyright Louis Dionne 2013-2016 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_FILL_HPP #define BOOST_HANA_FILL_HPP #include <boost/hana/fwd/fill.hpp> #include <boost/hana/concept/functor.hpp> #include <boost/hana/concept/sequence.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/dispatch.hpp> #include <boost/hana/core/make.hpp> #include <boost/hana/functional/always.hpp> #include <boost/hana/transform.hpp> #include <boost/hana/unpack.hpp> BOOST_HANA_NAMESPACE_BEGIN //! @cond template <typename Xs, typename Value> constexpr auto fill_t::operator()(Xs&& xs, Value&& value) const { using S = typename hana::tag_of<Xs>::type; using Fill = BOOST_HANA_DISPATCH_IF(fill_impl<S>, hana::Functor<S>::value ); #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS static_assert(hana::Functor<S>::value, "hana::fill(xs, value) requires 'xs' to be a Functor"); #endif return Fill::apply(static_cast<Xs&&>(xs), static_cast<Value&&>(value)); } //! @endcond template <typename Fun, bool condition> struct fill_impl<Fun, when<condition>> : default_ { template <typename Xs, typename Value> static constexpr auto apply(Xs&& xs, Value&& v) { return hana::transform(static_cast<Xs&&>(xs), hana::always(static_cast<Value&&>(v)) ); } }; template <typename S> struct fill_impl<S, when<Sequence<S>::value>> { //! @cond template <typename V> struct filler { V const& v; template <typename ...Xs> constexpr auto operator()(Xs const& ...xs) const { return hana::make<S>(((void)xs, v)...); } }; //! @endcond template <typename Xs, typename V> static constexpr auto apply(Xs const& xs, V const& v) { return hana::unpack(xs, filler<V>{v}); } }; BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_FILL_HPP