1 files changed, 76 insertions, 0 deletions
diff --git a/boost/hana/transform.hpp b/boost/hana/transform.hpp
new file mode 100644
index 0000000000..7ecba83602
--- /dev/null
+++ b/boost/hana/transform.hpp
@@ -0,0 +1,76 @@
+/*!
+@file
+Defines `boost::hana::transform`.
+
+@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_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