Add constexpr for clock_cast.

2019-12-18 00:21:54 +08:00
parent b9cd9c3fde
commit 66a5aa482e
2 changed files with 94 additions and 0 deletions
--- a/test/clock_cast_test/constexpr.pass.cpp
+++ b/test/clock_cast_test/constexpr.pass.cpp
@@ -0,0 +1,75 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2019 nanoric
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include "tz.h"
+#include <cassert>
+#include <type_traits>
+
+struct const_clock {
+  using duration =
+      typename std::common_type<std::chrono::system_clock::duration,
+          date::days>::type;
+  using rep = duration::rep;
+  using period = duration::period;
+  using time_point = std::chrono::time_point<const_clock, duration>;
+
+  static constexpr date::sys_days epoch { date::days { 1000 } };
+
+  template <typename Duration>
+  static std::chrono::time_point<std::chrono::system_clock,
+      typename std::common_type<Duration, date::days>::type>
+      CONSTCD11 to_sys(std::chrono::time_point<const_clock, Duration> const& tp)
+  {
+    return epoch + tp.time_since_epoch();
+  }
+
+  template <typename Duration>
+  static std::chrono::time_point<const_clock,
+      typename std::common_type<Duration, date::days>::type>
+      CONSTCD11 from_sys(
+          std::chrono::time_point<std::chrono::system_clock, Duration> const&
+              tp)
+  {
+    using res = std::chrono::time_point<const_clock,
+        typename std::common_type<Duration, date::days>::type>;
+    return res(tp - epoch);
+  }
+};
+
+int main()
+{
+  using namespace date;
+  using namespace std::chrono;
+  using const_days = time_point<const_clock, days>;
+
+  CONSTCD14 sys_days sys { days { 1024 } };
+  static_assert(sys.time_since_epoch().count() == 1024, "");
+
+  CONSTCD14 const_days c {clock_cast<const_clock>(sys)};
+  CONSTCD14 sys_days sys2 {clock_cast<system_clock>(c)};
+  CONSTCD14 sys_days sys3 { clock_cast<system_clock>(const_days(days(48))) };
+#if __cplusplus >= 201402L
+  static_assert(c.time_since_epoch().count() == 24, "");
+  static_assert(sys2.time_since_epoch().count() == 1024, "");
+  static_assert(sys3.time_since_epoch().count() == 1048, "");
+#endif
+}