/*!
|
@file
|
Defines `boost::hana::transform`.
|
|
@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_TRANSFORM_HPP
|
#define BOOST_HANA_TRANSFORM_HPP
|
|
#include <boost/hana/fwd/transform.hpp>
|
|
#include <boost/hana/bool.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/fwd/adjust_if.hpp>
|
#include <boost/hana/unpack.hpp>
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
//! @cond
|
template <typename Xs, typename F>
|
constexpr auto transform_t::operator()(Xs&& xs, F&& f) const {
|
using S = typename hana::tag_of<Xs>::type;
|
using Transform = BOOST_HANA_DISPATCH_IF(transform_impl<S>,
|
hana::Functor<S>::value
|
);
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
static_assert(hana::Functor<S>::value,
|
"hana::transform(xs, f) requires 'xs' to be a Functor");
|
#endif
|
|
return Transform::apply(static_cast<Xs&&>(xs), static_cast<F&&>(f));
|
}
|
//! @endcond
|
|
template <typename Fun, bool condition>
|
struct transform_impl<Fun, when<condition>> : default_ {
|
template <typename Xs, typename F>
|
static constexpr auto apply(Xs&& xs, F&& f) {
|
return hana::adjust_if(static_cast<Xs&&>(xs),
|
hana::always(hana::true_c),
|
static_cast<F&&>(f));
|
}
|
};
|
|
template <typename S>
|
struct transform_impl<S, when<Sequence<S>::value>> {
|
//! @cond
|
template <typename F>
|
struct transformer {
|
F f;
|
template <typename ...Xs>
|
constexpr auto operator()(Xs&& ...xs) const {
|
return hana::make<S>((*f)(static_cast<Xs&&>(xs))...);
|
}
|
};
|
//! @endcond
|
|
template <typename Xs, typename F>
|
static constexpr auto apply(Xs&& xs, F&& f) {
|
// We use a pointer to workaround a Clang 3.5 ICE
|
return hana::unpack(static_cast<Xs&&>(xs),
|
transformer<decltype(&f)>{&f});
|
}
|
};
|
BOOST_HANA_NAMESPACE_END
|
|
#endif // !BOOST_HANA_TRANSFORM_HPP
|
