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-rw-r--r--boost/hana/find_if.hpp78
1 files changed, 15 insertions, 63 deletions
diff --git a/boost/hana/find_if.hpp b/boost/hana/find_if.hpp
index 3c4e07fcb0..de9c3d3eea 100644
--- a/boost/hana/find_if.hpp
+++ b/boost/hana/find_if.hpp
@@ -3,6 +3,7 @@
Defines `boost::hana::find_if`.
@copyright Louis Dionne 2013-2017
+@copyright Jason Rice 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)
*/
@@ -17,19 +18,12 @@ Distributed under the Boost Software License, Version 1.0.
#include <boost/hana/bool.hpp>
#include <boost/hana/concept/iterable.hpp>
#include <boost/hana/concept/searchable.hpp>
-#include <boost/hana/concept/sequence.hpp>
#include <boost/hana/concept/struct.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
-#include <boost/hana/detail/decay.hpp>
-#include <boost/hana/drop_while.hpp>
#include <boost/hana/first.hpp>
-#include <boost/hana/front.hpp>
#include <boost/hana/functional/compose.hpp>
-#include <boost/hana/is_empty.hpp>
-#include <boost/hana/length.hpp>
-#include <boost/hana/not.hpp>
-#include <boost/hana/optional.hpp>
+#include <boost/hana/index_if.hpp>
#include <boost/hana/second.hpp>
#include <boost/hana/transform.hpp>
@@ -62,68 +56,26 @@ BOOST_HANA_NAMESPACE_BEGIN
};
namespace detail {
- template <typename Xs, typename Pred, std::size_t i, std::size_t N, bool Done>
- struct advance_until;
-
- template <typename Xs, typename Pred, std::size_t i, std::size_t N>
- struct advance_until<Xs, Pred, i, N, false>
- : advance_until<Xs, Pred, i + 1, N, static_cast<bool>(detail::decay<decltype(
- std::declval<Pred>()(hana::at_c<i>(std::declval<Xs>()))
- )>::type::value)>
- { };
-
- template <typename Xs, typename Pred, std::size_t N>
- struct advance_until<Xs, Pred, N, N, false> {
- template <typename Ys>
- static constexpr auto apply(Ys&&) {
- return hana::nothing;
- }
- };
+ template <typename Xs>
+ struct partial_at {
+ Xs const& xs;
- template <typename Xs, typename Pred, std::size_t i, std::size_t N>
- struct advance_until<Xs, Pred, i, N, true> {
- template <typename Ys>
- static constexpr auto apply(Ys&& ys) {
- return hana::just(hana::at_c<i - 1>(static_cast<Ys&&>(ys)));
+ template <typename I>
+ constexpr decltype(auto) operator()(I i) const {
+ return hana::at(xs, i);
}
};
}
- template <typename S>
- struct find_if_impl<S, when<Sequence<S>::value>> {
- template <typename Xs, typename Pred>
- static constexpr auto apply(Xs&& xs, Pred&&) {
- constexpr std::size_t N = decltype(hana::length(xs))::value;
- return detail::advance_until<Xs&&, Pred&&, 0, N, false>::apply(
- static_cast<Xs&&>(xs)
- );
- }
- };
-
- template <typename It>
- struct find_if_impl<It, when<hana::Iterable<It>::value && !Sequence<It>::value>> {
- template <typename Xs, typename Pred>
- static constexpr auto find_if_helper(Xs&& xs, Pred&& pred, hana::true_) {
- return hana::just(hana::front(
- hana::drop_while(static_cast<Xs&&>(xs),
- hana::compose(hana::not_, static_cast<Pred&&>(pred)))
- ));
- }
-
- template <typename Xs, typename Pred>
- static constexpr auto find_if_helper(Xs&&, Pred&&, hana::false_) {
- return hana::nothing;
- }
-
+ template <typename Tag>
+ struct find_if_impl<Tag, when<Iterable<Tag>::value>> {
template <typename Xs, typename Pred>
static constexpr auto apply(Xs&& xs, Pred&& pred) {
- constexpr bool found = !decltype(
- hana::is_empty(hana::drop_while(static_cast<Xs&&>(xs),
- hana::compose(hana::not_, static_cast<Pred&&>(pred))))
- )::value;
- return find_if_impl::find_if_helper(static_cast<Xs&&>(xs),
- static_cast<Pred&&>(pred),
- hana::bool_<found>{});
+ using Result = decltype(hana::index_if(
+ static_cast<Xs&&>(xs), static_cast<Pred&&>(pred)));
+
+ return hana::transform(Result{},
+ detail::partial_at<std::decay_t<Xs>>{static_cast<Xs&&>(xs)});
}
};