refactor: add HasDataSequenceNumber() accessor to MergingSnapshotUpdate

Author: WZhuo

src/iceberg/update/merging_snapshot_update.h

@@ -141,6 +141,11 @@ class ICEBERG_EXPORT MergingSnapshotUpdate : public SnapshotUpdate {
   /// \brief Override the data sequence number assigned to all newly-added data files.
   void SetNewDataFilesDataSequenceNumber(int64_t sequence_number);
 
+  /// \brief Returns true if SetNewDataFilesDataSequenceNumber was called.
+  bool HasDataSequenceNumber() const {
+    return new_data_files_data_seq_number_.has_value();
+  }
+
   /// \brief Set case sensitivity for row filter and expression evaluation.
   void CaseSensitive(bool case_sensitive);
 

src/iceberg/update/rewrite_files.cc

@@ -79,15 +79,13 @@ RewriteFiles& RewriteFiles::AddDeleteFile(const std::shared_ptr<DataFile>& delet
 
 RewriteFiles& RewriteFiles::SetDataSequenceNumber(int64_t sequence_number) {
   SetNewDataFilesDataSequenceNumber(sequence_number);
-  data_sequence_number_set_ = true;
   return *this;
 }
 
 RewriteFiles& RewriteFiles::RewriteDataFiles(
     const std::vector<std::shared_ptr<DataFile>>& files_to_delete,
     const std::vector<std::shared_ptr<DataFile>>& files_to_add, int64_t sequence_number) {
   SetNewDataFilesDataSequenceNumber(sequence_number);
-  data_sequence_number_set_ = true;
   Rewrite(files_to_delete, {}, files_to_add, {});
   return *this;
 }
@@ -169,7 +167,7 @@ Status RewriteFiles::Validate(const TableMetadata& current_metadata,
     auto io = ctx_->table->io();
     ICEBERG_RETURN_UNEXPECTED(MergingSnapshotUpdate::ValidateNoNewDeletesForDataFiles(
         current_metadata, starting_snapshot_id_, replaced_data_files_, snapshot,
-        std::move(io), data_sequence_number_set_));
+        std::move(io), HasDataSequenceNumber()));
   }
 
   return {};

src/iceberg/update/rewrite_files.h

@@ -180,15 +180,6 @@ class ICEBERG_EXPORT RewriteFiles : public MergingSnapshotUpdate {
 
   /// \brief Optional snapshot ID boundary for validation scope.
   std::optional<int64_t> starting_snapshot_id_;
-
-  /// \brief Whether a data sequence number has been set for this operation.
-  ///
-  /// Mirrors MergingSnapshotUpdate::new_data_files_data_seq_number_ which is private.
-  /// Needed because calling the instance overload of ValidateNoNewDeletesForDataFiles
-  /// is ambiguous with the static overload (which has a default bool argument). The
-  /// instance overload derives ignore_equality_deletes from the base class private
-  /// field, so we track it here to pass explicitly to the static overload.
-  bool data_sequence_number_set_ = false;
 };
 
 }  // namespace iceberg