Add datetime::is_leap_year (#8711)

Part 1 of #8677 

This PR adds `datetime::is_leap_year`. The function returns `true` for datetime column rows with leap year; `false` for rows with non leap years, and `null` for null rows.

Authors:
  - Michael Wang (https://github.com/isVoid)

Approvers:
  - Mark Harris (https://github.com/harrism)
  - Karthikeyan (https://github.com/karthikeyann)

URL: #8711

cpp/include/cudf/datetime.hpp

@@ -189,6 +189,23 @@ std::unique_ptr<cudf::column> add_calendrical_months(
   cudf::column_view const& timestamps,
   cudf::column_view const& months,
   rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
+/**
+ * @brief  Check if the year of the given date is a leap year
+ *
+ * `output[i] == true` if year of `column[i]` is a leap year
+ * `output[i] == false` if year of `column[i]` is not a leap year
+ * `output[i] is null` if `column[i]` is null
+ *
+ * @param[in] cudf::column_view of the input datetime values
+ *
+ * @returns cudf::column of datatype BOOL8 truth value of the corresponding date
+ * @throw cudf::logic_error if input column datatype is not a TIMESTAMP
+ */
+std::unique_ptr<cudf::column> is_leap_year(
+  cudf::column_view const& column,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
 /** @} */  // end of group
 }  // namespace datetime
 }  // namespace cudf

cpp/include/cudf/detail/datetime.hpp

@@ -124,6 +124,17 @@ std::unique_ptr<cudf::column> add_calendrical_months(
   cudf::column_view const& months,
   rmm::cuda_stream_view stream        = rmm::cuda_stream_default,
   rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
+/**
+ * @copydoc cudf::is_leap_year(cudf::column_view const&, rmm::mr::device_memory_resource *)
+ *
+ * @param stream CUDA stream used for device memory operations and kernel launches.
+ */
+std::unique_ptr<cudf::column> is_leap_year(
+  cudf::column_view const& column,
+  rmm::cuda_stream_view stream        = rmm::cuda_stream_default,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
 }  // namespace detail
 }  // namespace datetime
 }  // namespace cudf

cpp/src/datetime/datetime_ops.cu

@@ -19,9 +19,9 @@
 #include <cudf/column/column_factories.hpp>
 #include <cudf/column/column_view.hpp>
 #include <cudf/datetime.hpp>
+#include <cudf/detail/datetime.hpp>
 #include <cudf/detail/null_mask.hpp>
 #include <cudf/detail/nvtx/ranges.hpp>
-#include <cudf/null_mask.hpp>
 #include <cudf/table/table_view.hpp>
 #include <cudf/types.hpp>
 #include <cudf/utilities/traits.hpp>
@@ -127,6 +127,17 @@ struct extract_day_num_of_year {
   }
 };
 
+struct is_leap_year_op {
+  template <typename Timestamp>
+  CUDA_DEVICE_CALLABLE bool operator()(Timestamp const ts) const
+  {
+    using namespace cuda::std::chrono;
+    auto const days_since_epoch = floor<days>(ts);
+    auto const date             = year_month_day(days_since_epoch);
+    return date.year().is_leap();
+  }
+};
+
 // Apply the functor for every element/row in the input column to create the output column
 template <typename TransformFunctor, typename OutputColT>
 struct launch_functor {
@@ -357,6 +368,14 @@ std::unique_ptr<column> day_of_year(column_view const& column,
   return detail::apply_datetime_op<detail::extract_day_num_of_year, cudf::type_id::INT16>(
     column, stream, mr);
 }
+
+std::unique_ptr<column> is_leap_year(column_view const& column,
+                                     rmm::cuda_stream_view stream,
+                                     rmm::mr::device_memory_resource* mr)
+{
+  return apply_datetime_op<is_leap_year_op, type_id::BOOL8>(column, stream, mr);
+}
+
 }  // namespace detail
 
 std::unique_ptr<column> extract_year(column_view const& column, rmm::mr::device_memory_resource* mr)
@@ -426,5 +445,12 @@ std::unique_ptr<cudf::column> add_calendrical_months(cudf::column_view const& ti
   return detail::add_calendrical_months(
     timestamp_column, months_column, rmm::cuda_stream_default, mr);
 }
+
+std::unique_ptr<column> is_leap_year(column_view const& column, rmm::mr::device_memory_resource* mr)
+{
+  CUDF_FUNC_RANGE();
+  return detail::is_leap_year(column, rmm::cuda_stream_default, mr);
+}
+
 }  // namespace datetime
 }  // namespace cudf

cpp/tests/datetime/datetime_ops_test.cpp

@@ -26,6 +26,8 @@
 #include <cudf/types.hpp>
 #include <cudf/wrappers/timestamps.hpp>
 
+#define XXX false  // stub for null values
+
 template <typename T>
 struct NonTimestampTest : public cudf::test::BaseFixture {
   cudf::data_type type() { return cudf::data_type{cudf::type_to_id<T>()}; }
@@ -532,4 +534,37 @@ TEST_F(BasicDatetimeOpsTest, TestAddMonthsWithSecondsAndNullValues)
     true);
 }
 
+TEST_F(BasicDatetimeOpsTest, TestIsLeapYear)
+{
+  using namespace cudf::test;
+  using namespace cudf::datetime;
+  using namespace cuda::std::chrono;
+
+  // Time in seconds since epoch
+  // Dates converted using epochconverter.com
+  auto timestamps_s =
+    cudf::test::fixed_width_column_wrapper<cudf::timestamp_s, cudf::timestamp_s::rep>{
+      {
+        1594332839L,    // 2020-07-09 10:13:59 GMT - leap year
+        0L,             // null
+        915148800L,     // 1999-01-01 00:00:00 GMT - non leap year
+        -11663029161L,  // 1600-5-31 05:40:39 GMT - leap year
+        707904541L,     // 1992-06-07 08:09:01 GMT - leap year
+        2181048447L,    // 1900-11-20 09:12:33 GMT - non leap year
+        0L,             // UNIX EPOCH 1970-01-01 00:00:00 GMT - non leap year
+        -12212553600L,  // First full year of Gregorian Calandar 1583-01-01 00:00:00 - non-leap-year
+        0L,             // null
+        13591632822L,   // 2400-09-13 13:33:42 GMT - leap year
+        4539564243L,    // 2113-11-08 06:04:03 GMT - non leap year
+        0L              // null
+      },
+      {true, false, true, true, true, true, true, true, false, true, true, false}};
+
+  CUDF_TEST_EXPECT_COLUMNS_EQUAL(
+    *is_leap_year(timestamps_s),
+    cudf::test::fixed_width_column_wrapper<bool>{
+      {true, XXX, false, true, true, false, false, false, XXX, true, false, XXX},
+      {true, false, true, true, true, true, true, true, false, true, true, false}});
+}
+
 CUDF_TEST_PROGRAM_MAIN()