+ EventTimeFn<> template; automate common timestamp patterns

include/xo/reactor/EventTimeFn2.hpp

@@ -0,0 +1,60 @@
+/* @file EventTimeFn2.hpp */
+
+#pragma once
+
+#include "xo/refcnt/Refcounted.hpp"
+#include <timeutil/timeutil.hpp>
+
+namespace xo {
+    namespace reactor {
+        template <typename Event>
+        class EventTimeFn {
+        public:
+            using utc_nanos = xo::time::utc_nanos;
+            using event_t = Event;
+
+        public:
+            static utc_nanos event_tm(event_t const & ev) { return ev.tm(); }
+
+            utc_nanos operator()(event_t const & ev) const { return EventTimeFn::event_tm(ev); }
+        };
+
+        template <typename T>
+        class EventTimeFn<xo::ref::rp<T>> {
+        public:
+            using utc_nanos = xo::time::utc_nanos;
+            using event_t = xo::ref::rp<T>;
+
+        public:
+            static utc_nanos event_tm(event_t const & ev) { return ev->tm(); }
+
+            utc_nanos operator()(event_t const & ev) const { return EventTimeFn::event_tm(ev); }
+        };
+
+        template <typename T>
+        class EventTimeFn<T*> {
+        public:
+            using utc_nanos = xo::time::utc_nanos;
+            using event_t = T*;
+
+        public:
+            static utc_nanos event_tm(event_t ev) { return ev->tm(); }
+
+            utc_nanos operator()(event_t const & ev) const { return EventTimeFn::event_tm(ev); }
+        };
+
+        template <typename T>
+        class EventTimeFn<std::pair<xo::time::utc_nanos, T>> {
+        public:
+            using utc_nanos = xo::time::utc_nanos;
+            using event_t = std::pair<xo::time::utc_nanos, T>;
+
+        public:
+            static utc_nanos event_tm(event_t const & ev) { return ev.first; }
+
+            utc_nanos operator()(event_t const & ev) const { return EventTimeFn::event_tm(ev); }
+        };
+    } /*namespace reactor*/
+} /*namespace xo*/
+
+/* end EventTimeFn2.hpp */