GH-43183: [C++] Add date{32,64} to date{32,64} cast (#43192)

### Rationale for this change This one seems to be missing, see #43183 ### What changes are included in this PR? ### Are these changes tested? I'm not sure what the best place is to test this, please advise ### Are there any user-facing changes? * GitHub Issue: #43183 Lead-authored-by: Fokko <[email protected]> Co-authored-by: Fokko Driesprong <[email protected]> Co-authored-by: Hyunseok Seo <[email protected]> Signed-off-by: Antoine Pitrou <[email protected]>
apache · Jul 10, 2024 · 5e451d8 · 5e451d8
1 parent dffff1c
commit 5e451d8
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Showing 3 changed files with 20 additions and 2 deletions.
diff --git a/cpp/src/arrow/compute/kernels/scalar_cast_temporal.cc b/cpp/src/arrow/compute/kernels/scalar_cast_temporal.cc
@@ -510,9 +510,12 @@ void AddCrossUnitCastNoPreallocate(CastFunction* func) {
 
 std::shared_ptr<CastFunction> GetDate32Cast() {
   auto func = std::make_shared<CastFunction>("cast_date32", Type::DATE32);
-  auto out_ty = date32();
+  const auto& out_ty = date32();
   AddCommonCasts(Type::DATE32, out_ty, func.get());
 
+  // date32 -> date32
+  AddZeroCopyCast(Type::DATE32, date32(), date32(), func.get());
+
   // int32 -> date32
   AddZeroCopyCast(Type::INT32, int32(), date32(), func.get());
 
@@ -532,9 +535,12 @@ std::shared_ptr<CastFunction> GetDate32Cast() {
 
 std::shared_ptr<CastFunction> GetDate64Cast() {
   auto func = std::make_shared<CastFunction>("cast_date64", Type::DATE64);
-  auto out_ty = date64();
+  const auto& out_ty = date64();
   AddCommonCasts(Type::DATE64, out_ty, func.get());
 
+  // date64 -> date64
+  AddZeroCopyCast(Type::DATE64, date64(), date64(), func.get());
+
   // int64 -> date64
   AddZeroCopyCast(Type::INT64, int64(), date64(), func.get());
 

diff --git a/cpp/src/arrow/compute/kernels/scalar_cast_test.cc b/cpp/src/arrow/compute/kernels/scalar_cast_test.cc
@@ -1646,6 +1646,10 @@ TEST(Cast, DateToDate) {
         86400000,
        864000000])");
 
+  // Zero copy
+  CheckCast(day_32, day_32);
+  CheckCast(day_64, day_64);
+
   // Multiply promotion
   CheckCast(day_32, day_64);
 

diff --git a/python/pyarrow/tests/test_compute.py b/python/pyarrow/tests/test_compute.py
@@ -1842,6 +1842,14 @@ def test_cast():
     assert pc.cast(arr, expected.type) == expected
 
 
+@pytest.mark.parametrize('value_type', [pa.date32(), pa.date64()])
+def test_identity_cast_dates(value_type):
+    dt = datetime.date(1990, 3, 1)
+
+    arr = pa.array([dt], type=value_type)
+    assert pc.cast(arr, value_type) == arr
+
+
 @pytest.mark.parametrize('value_type', numerical_arrow_types)
 def test_fsl_to_fsl_cast(value_type):
     # Different field name and different type.