WillAyd commented on a change in pull request #12248:
URL: https://github.com/apache/arrow/pull/12248#discussion_r803224874



##########
File path: cpp/src/arrow/compute/kernels/scalar_cast_nested.cc
##########
@@ -150,6 +150,104 @@ void AddListCast(CastFunction* func) {
   DCHECK_OK(func->AddKernel(SrcType::type_id, std::move(kernel)));
 }
 
+struct CastStruct {
+  static Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+    const CastOptions& options = CastState::Get(ctx);
+    const auto in_field_count =
+        checked_cast<const StructType&>(*batch[0].type()).num_fields();
+    const auto out_field_count =
+        checked_cast<const StructType&>(*out->type()).num_fields();
+
+    if (in_field_count != out_field_count) {
+      return Status::TypeError("struct field sizes do not match: ",
+                               batch[0].type()->ToString(), " ", 
out->type()->ToString());
+    }
+
+    for (int i = 0; i < in_field_count; ++i) {
+      const auto in_field_name =
+          checked_cast<const StructType&>(*batch[0].type()).field(i)->name();
+      const auto out_field_name =
+          checked_cast<const StructType&>(*out->type()).field(i)->name();
+      if (in_field_name != out_field_name) {
+        return Status::TypeError(
+            "struct field names do not match: ", batch[0].type()->ToString(), 
" ",
+            out->type()->ToString());
+      }
+
+      const auto in_field_nullable =
+          checked_cast<const 
StructType&>(*batch[0].type()).field(i)->nullable();
+      const auto out_field_nullable =
+          checked_cast<const StructType&>(*out->type()).field(i)->nullable();
+
+      if (in_field_nullable && !out_field_nullable) {
+        return Status::TypeError("cannot cast nullable struct to non-nullable 
struct: ",
+                                 batch[0].type()->ToString(), " ",
+                                 out->type()->ToString());
+      }
+    }
+
+    for (int i = 0; i < in_field_count; ++i) {
+      const auto in_field_name =
+          checked_cast<const StructType&>(*batch[0].type()).field(i)->name();
+      const auto out_field_name =
+          checked_cast<const StructType&>(*out->type()).field(i)->name();
+      if (in_field_name != out_field_name) {
+        return Status::TypeError(
+            "struct field names do not match: ", batch[0].type()->ToString(), 
" ",
+            out->type()->ToString());
+      }
+    }
+
+    if (out->kind() == Datum::SCALAR) {
+      const auto& in_scalar = checked_cast<const 
StructScalar&>(*batch[0].scalar());
+      auto out_scalar = checked_cast<StructScalar*>(out->scalar().get());
+
+      DCHECK(!out_scalar->is_valid);
+      if (in_scalar.is_valid) {
+        for (int i = 0; i < in_field_count; i++) {
+          auto values = in_scalar.value[i];
+          auto target_type = out->type()->field(i)->type();
+          ARROW_ASSIGN_OR_RAISE(Datum cast_values,
+                                Cast(values, target_type, options, 
ctx->exec_context()));
+          DCHECK_EQ(Datum::SCALAR, cast_values.kind());
+          out_scalar->value.push_back(cast_values.scalar());
+        }
+        out_scalar->is_valid = true;
+      }
+      return Status::OK();
+    }
+
+    const ArrayData& in_array = *batch[0].array();
+    ArrayData* out_array = out->mutable_array();
+    out_array->buffers = in_array.buffers;

Review comment:
       First part of this is done. For the sake of comprehensiveness I tried 
introducing `null` values into the main test, but didn't make a difference at 
all. Is that different from manually providing a bitmap as you've described?




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: [email protected]

For queries about this service, please contact Infrastructure at:
[email protected]


Reply via email to