fix: wrong wrapping in time_of_day::operator-.

project-tsurugi · Jul 26, 2024 · ad142ac · ad142ac
1 parent 625bbca
commit ad142ac
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Showing 2 changed files with 35 additions and 9 deletions.
diff --git a/include/takatori/datetime/time_of_day.h b/include/takatori/datetime/time_of_day.h
@@ -27,11 +27,14 @@ class time_of_day {
     /// @brief time offset type.
     using difference_type = std::chrono::nanoseconds;
 
-    /// @brief the max value.
-    static constexpr time_unit max_value {
-        std::chrono::duration_cast<time_unit>(second_unit { 86400 }) - time_unit { 1 },
+    /// @brief the modulo of the day in the time unit.
+    static constexpr time_unit modulo {
+        std::chrono::duration_cast<time_unit>(second_unit { 86'400 } ),
     };
 
+    /// @brief the max value.
+    static constexpr time_unit max_value { modulo - time_unit { 1 }, };
+
     /**
      * @brief creates a new instance which represents 00:00:00 of day.
      */
@@ -56,11 +59,13 @@ class time_of_day {
             std::uint32_t hour,
             std::uint32_t minute,
             std::uint32_t second,
-            time_unit subsecond = time_unit::zero()) noexcept
-        : elapsed_(std::chrono::duration<std::uint64_t, std::chrono::hours::period>(hour)
-                + std::chrono::duration<std::uint64_t, std::chrono::minutes::period>(minute)
-                + std::chrono::duration<std::uint64_t, std::chrono::seconds::period>(second)
-                + subsecond)
+            time_unit subsecond = time_unit::zero()) noexcept:
+        time_of_day {
+                std::chrono::duration<std::uint64_t, std::chrono::hours::period>(hour)
+                        + std::chrono::duration<std::uint64_t, std::chrono::minutes::period>(minute)
+                        + std::chrono::duration<std::uint64_t, std::chrono::seconds::period>(second)
+                        + subsecond
+        }
     {}
 
     /**
@@ -145,7 +150,10 @@ class time_of_day {
  * @return the computed time
  */
 inline constexpr time_of_day operator+(time_of_day a, time_of_day::difference_type b) noexcept {
-    return time_of_day { a.time_since_epoch() + b };
+    constexpr auto signed_modulo = std::chrono::duration_cast<time_of_day::difference_type>(time_of_day::modulo);
+    auto b_normalized = std::chrono::duration_cast<time_of_day::time_unit>(signed_modulo + b % signed_modulo);
+    auto r_normalized = (a.time_since_epoch() + b_normalized) % time_of_day::modulo;
+    return time_of_day { r_normalized };
 }
 
 /**

diff --git a/test/takatori/datetime/time_of_day_test.cpp b/test/takatori/datetime/time_of_day_test.cpp
@@ -27,6 +27,24 @@ TEST_F(time_of_day_test, hms) {
     EXPECT_EQ(d.subsecond(), c::milliseconds(789));
 }
 
+TEST_F(time_of_day_test, plus_difference_in_range) {
+    time_of_day a { 1, 0, 0 };
+    auto r = a + std::chrono::hours { 2 };
+    EXPECT_EQ(r.time_since_epoch(), std::chrono::hours { 3 });
+}
+
+TEST_F(time_of_day_test, plus_difference_wrap_positive) {
+    time_of_day a { 12, 0, 0 };
+    auto r = a + std::chrono::hours { 13 };
+    EXPECT_EQ(r.time_since_epoch(), std::chrono::hours { 1 });
+}
+
+TEST_F(time_of_day_test, plus_difference_wrap_negative) {
+    time_of_day a { 12, 0, 0 };
+    auto r = a + std::chrono::hours { -13 };
+    EXPECT_EQ(r.time_since_epoch(), std::chrono::hours { 23 });
+}
+
 TEST_F(time_of_day_test, output) {
     time_of_day d { 12, 34, 56, unit { 789'000'000 } };
     std::cout << d << std::endl;