[C++] FixedSizeListBuilder should have UnsafeAppend methods #45723

cpp/src/arrow/array/builder_nested.cc

@@ -204,6 +204,10 @@ Status FixedSizeListBuilder::Append() {
   return Status::OK();
 }
 
+void FixedSizeListBuilder::UnsafeAppend() {
+   UnsafeAppendToBitmap(true);
+}
+
 Status FixedSizeListBuilder::AppendValues(int64_t length, const uint8_t* valid_bytes) {
   RETURN_NOT_OK(Reserve(length));
   UnsafeAppendToBitmap(valid_bytes, length);
@@ -216,12 +220,22 @@ Status FixedSizeListBuilder::AppendNull() {
   return value_builder_->AppendNulls(list_size_);
 }
 
+void FixedSizeListBuilder::UnsafeAppendNull() {
+   UnsafeAppendToBitmap(false);
+   (void) value_builder_->AppendNulls(list_size_);
+}
+
 Status FixedSizeListBuilder::AppendNulls(int64_t length) {
   RETURN_NOT_OK(Reserve(length));
   UnsafeAppendToBitmap(length, false);
   return value_builder_->AppendNulls(list_size_ * length);
 }
 
+void FixedSizeListBuilder::UnsafeAppendNulls(int64_t length) {
+   UnsafeAppendToBitmap(length, false);
+   (void) value_builder_->AppendNulls(list_size_ * length);
+}
+
 Status FixedSizeListBuilder::ValidateOverflow(int64_t new_elements) {
   auto new_length = value_builder_->length() + new_elements;
   if (new_elements != list_size_) {

cpp/src/arrow/array/builder_nested.h

@@ -672,6 +672,7 @@ class ARROW_EXPORT FixedSizeListBuilder : public ArrayBuilder {
   /// using the child array builder.
   Status Append();
 
+  void UnsafeAppend();
   /// \brief Vector append
   ///
   /// If passed, valid_bytes will be read and any zero byte
@@ -687,12 +688,14 @@ class ARROW_EXPORT FixedSizeListBuilder : public ArrayBuilder {
   /// The child array builder will have the appropriate number of nulls appended
   /// automatically.
   Status AppendNull() final;
+  void UnsafeAppendNull();
 
   /// \brief Append length null fixed length lists.
   ///
   /// The child array builder will have the appropriate number of nulls appended
   /// automatically.
   Status AppendNulls(int64_t length) final;
+  void UnsafeAppendNulls(int64_t length);
 
   Status ValidateOverflow(int64_t new_elements);
 

cpp/src/arrow/compute/kernels/scalar_nested.cc

@@ -361,7 +361,8 @@ struct ListSlice {
                                           BuilderType* out_list_builder) {
     if constexpr (kIsFixedSizeOutput) {
       DCHECK_EQ(out_list_builder->type()->id(), Type::FIXED_SIZE_LIST);
-      return out_list_builder->Append();
+      out_list_builder->UnsafeAppend();
+      return Status::OK();
     } else {
       return out_list_builder->Append(/*is_valid=*/true, slice_length);
     }

cpp/src/arrow/compute/kernels/scalar_string_ascii.cc

@@ -2431,9 +2431,9 @@ struct ExtractRegexSpan : ExtractRegexBase {
             int64_t size = found_values[i].size();
             array_builders[i]->UnsafeAppend(static_cast<OffsetCType>(begin));
             array_builders[i]->UnsafeAppend(static_cast<OffsetCType>(size));
-            ARROW_RETURN_NOT_OK(span_builders[i]->Append());
+            span_builders[i]->UnsafeAppend();
           } else {
-            ARROW_RETURN_NOT_OK(span_builders[i]->AppendNull());
+            span_builders[i]->UnsafeAppendNull();
           }
         }
         ARROW_RETURN_NOT_OK(struct_builder->Append());

cpp/src/arrow/testing/fixed_width_test_util.cc

@@ -137,7 +137,7 @@ Status NestedListGenerator::AppendNestedList(ArrayBuilder* nested_builder,
     if (type->id() == Type::FIXED_SIZE_LIST) {
       auto* fsl_builder = checked_cast<FixedSizeListBuilder*>(builder);
       assert(list_size == checked_cast<FixedSizeListType&>(*type).list_size());
-      RETURN_NOT_OK(fsl_builder->Append());
+      fsl_builder->UnsafeAppend();
       builder = fsl_builder->value_builder();
     } else {  // type->id() == Type::LIST)
       auto* list_builder = checked_cast<ListBuilder*>(builder);