1 files changed, 51 insertions, 0 deletions
diff --git a/boost/hana/contains.hpp b/boost/hana/contains.hpp
new file mode 100644
index 0000000000..8b8599d8f3
--- /dev/null
+++ b/boost/hana/contains.hpp
@@ -0,0 +1,51 @@
+/*!
+@file
+Defines `boost::hana::contains` and `boost::hana::in`.
+
+@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_CONTAINS_HPP
+#define BOOST_HANA_CONTAINS_HPP
+
+#include <boost/hana/fwd/contains.hpp>
+
+#include <boost/hana/any_of.hpp>
+#include <boost/hana/concept/searchable.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/equal.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! @cond
+    template <typename Xs, typename Key>
+    constexpr auto contains_t::operator()(Xs&& xs, Key&& key) const {
+        using S = typename hana::tag_of<Xs>::type;
+        using Contains = BOOST_HANA_DISPATCH_IF(contains_impl<S>,
+            hana::Searchable<S>::value
+        );
+
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::Searchable<S>::value,
+        "hana::contains(xs, key) requires 'xs' to be a Searchable");
+    #endif
+
+        return Contains::apply(static_cast<Xs&&>(xs),
+                               static_cast<Key&&>(key));
+    }
+    //! @endcond
+
+    template <typename S, bool condition>
+    struct contains_impl<S, when<condition>> : default_ {
+        template <typename Xs, typename X>
+        static constexpr auto apply(Xs&& xs, X&& x) {
+            return hana::any_of(static_cast<Xs&&>(xs),
+                    hana::equal.to(static_cast<X&&>(x)));
+        }
+    };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_CONTAINS_HPP