felipecrv commented on code in PR #42117:
URL: https://github.com/apache/arrow/pull/42117#discussion_r1657131888
##########
cpp/src/arrow/compute/kernels/vector_selection_internal.cc:
##########
@@ -612,6 +612,59 @@ struct ListSelectionImpl : public
Selection<ListSelectionImpl<Type>, Type> {
}
};
+template <typename Type>
+struct ListViewSelectionImpl : public Selection<ListViewSelectionImpl<Type>,
Type> {
+ using offset_type = typename Type::offset_type;
+
+ using Base = Selection<ListViewSelectionImpl<Type>, Type>;
+ LIFT_BASE_MEMBERS();
+
+ TypedBufferBuilder<offset_type> offsets_builder;
+ TypedBufferBuilder<offset_type> sizes_builder;
+
+ ListViewSelectionImpl(KernelContext* ctx, const ExecSpan& batch, int64_t
output_length,
+ ExecResult* out)
+ : Base(ctx, batch, output_length, out),
+ offsets_builder(ctx->memory_pool()),
+ sizes_builder(ctx->memory_pool()) {}
+
+ template <typename Adapter>
+ Status GenerateOutput() {
+ auto* offsets = this->values.template GetValues<offset_type>(1);
+ auto* sizes = this->values.template GetValues<offset_type>(2);
+
+ offset_type null_list_view_offset = 0;
+ Adapter adapter(this);
+ RETURN_NOT_OK(adapter.Generate(
+ [&](int64_t index) {
+ offset_type value_offset = offsets[index];
+ offset_type value_length = sizes[index];
+ offsets_builder.UnsafeAppend(value_offset);
+ sizes_builder.UnsafeAppend(value_length);
+ null_list_view_offset = value_offset + value_length;
+ return Status::OK();
+ },
+ [&]() {
+ offsets_builder.UnsafeAppend(null_list_view_offset);
Review Comment:
To keep the offsets of list-view sorted just like they are in regular lists.
It makes casting to regular lists much easier.
Remember the invariants we discussed during the specification of list-views?
We need `offset[i] + sizes[i]` to be `<= values.length`, so by having `sizes[i]
== 0` I can have `offsets` that behave just like normal list offsets.
##########
cpp/src/arrow/compute/kernels/vector_selection_internal.cc:
##########
@@ -612,6 +612,59 @@ struct ListSelectionImpl : public
Selection<ListSelectionImpl<Type>, Type> {
}
};
+template <typename Type>
+struct ListViewSelectionImpl : public Selection<ListViewSelectionImpl<Type>,
Type> {
+ using offset_type = typename Type::offset_type;
+
+ using Base = Selection<ListViewSelectionImpl<Type>, Type>;
+ LIFT_BASE_MEMBERS();
+
+ TypedBufferBuilder<offset_type> offsets_builder;
+ TypedBufferBuilder<offset_type> sizes_builder;
+
+ ListViewSelectionImpl(KernelContext* ctx, const ExecSpan& batch, int64_t
output_length,
+ ExecResult* out)
+ : Base(ctx, batch, output_length, out),
+ offsets_builder(ctx->memory_pool()),
+ sizes_builder(ctx->memory_pool()) {}
+
+ template <typename Adapter>
+ Status GenerateOutput() {
+ auto* offsets = this->values.template GetValues<offset_type>(1);
+ auto* sizes = this->values.template GetValues<offset_type>(2);
+
+ offset_type null_list_view_offset = 0;
+ Adapter adapter(this);
+ RETURN_NOT_OK(adapter.Generate(
+ [&](int64_t index) {
+ offset_type value_offset = offsets[index];
+ offset_type value_length = sizes[index];
+ offsets_builder.UnsafeAppend(value_offset);
+ sizes_builder.UnsafeAppend(value_length);
+ null_list_view_offset = value_offset + value_length;
+ return Status::OK();
+ },
+ [&]() {
+ offsets_builder.UnsafeAppend(null_list_view_offset);
Review Comment:
Done.
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