1 files changed, 76 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/map/map.cpp b/src/boost/libs/hana/example/map/map.cpp
new file mode 100644
index 000000000..a04ecfd73
--- /dev/null
+++ b/src/boost/libs/hana/example/map/map.cpp
@@ -0,0 +1,76 @@
+// Copyright Louis Dionne 2013-2017
+// Distributed under the Boost Software License, Version 1.0.
+
+#include <boost/hana/assert.hpp>
+#include <boost/hana/at_key.hpp>
+#include <boost/hana/contains.hpp>
+#include <boost/hana/map.hpp>
+#include <boost/hana/pair.hpp>
+#include <boost/hana/string.hpp>
+
+#include <functional>
+#include <string>
+#include <vector>
+namespace hana = boost::hana;
+
+
+template <typename ...Events>
+struct event_system {
+    using Callback = std::function<void()>;
+    hana::map<hana::pair<Events, std::vector<Callback>>...> map_;
+
+    template <typename Event, typename F>
+    void on(Event e, F handler) {
+        auto is_known_event = hana::contains(map_, e);
+        static_assert(is_known_event,
+            "trying to add a handler to an unknown event");
+
+        map_[e].push_back(handler);
+    }
+
+    template <typename Event>
+    void trigger(Event e) const {
+        auto is_known_event = hana::contains(map_, e);
+        static_assert(is_known_event,
+            "trying to trigger an unknown event");
+
+        for (auto& handler : this->map_[e])
+            handler();
+    }
+};
+
+template <typename ...Events>
+event_system<Events...> make_event_system(Events ...events) {
+    return {};
+}
+
+
+int main() {
+    auto events = make_event_system(
+        BOOST_HANA_STRING("foo"),
+        BOOST_HANA_STRING("bar"),
+        BOOST_HANA_STRING("baz")
+    );
+
+    std::vector<std::string> triggered_events;
+    events.on(BOOST_HANA_STRING("foo"), [&] {
+        triggered_events.push_back("foo:1");
+    });
+    events.on(BOOST_HANA_STRING("foo"), [&] {
+        triggered_events.push_back("foo:2");
+    });
+    events.on(BOOST_HANA_STRING("bar"), [&] {
+        triggered_events.push_back("bar:1");
+    });
+    events.on(BOOST_HANA_STRING("baz"), [&] {
+        triggered_events.push_back("baz:1");
+    });
+
+    events.trigger(BOOST_HANA_STRING("foo"));
+    events.trigger(BOOST_HANA_STRING("bar"));
+    events.trigger(BOOST_HANA_STRING("baz"));
+
+    BOOST_HANA_RUNTIME_CHECK(triggered_events == std::vector<std::string>{
+        "foo:1", "foo:2", "bar:1", "baz:1"
+    });
+}