apacheGH-38630: [MATLAB] arrow.array.BooleanArray's toMATLAB meth…

…od does not take slice offsets into account (apache#38636) ### Rationale for this change While working on apache#38415, I noticed that the `toMATLAB` method of `arrow.array.BooleanArray` does not take the slice offset into account. This will cause the `toMATLAB` method to return the wrong value. ### What changes are included in this PR? 1. Updated `arrow::matlab::bit::unpack` function to accept a `start_offset` as input. 2. Updated clients (`BooleanArray::toMATLAB` and `Array::getValid`) to supply the array `offset` as the `start_offset`. ### Are these changes tested? The existing tests cover these changes. Additionally, the changes for apache#38415 will include tests that verify the `toMATLAB` method returns the correct MATLAB array when the underlying Arrow array has been sliced. ### Are there any user-facing changes? No. * Closes: apache#38630 Authored-by: Sarah Gilmore <[email protected]> Signed-off-by: Kevin Gurney <[email protected]>
loicalleyne · Nov 13, 2023 · bad2c66 · bad2c66
1 parent 40df49e
commit bad2c66
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Showing 4 changed files with 4 additions and 5 deletions.
diff --git a/matlab/src/cpp/arrow/matlab/array/proxy/array.cc b/matlab/src/cpp/arrow/matlab/array/proxy/array.cc
@@ -100,7 +100,7 @@ namespace arrow::matlab::array::proxy {
         }
 
         auto validity_bitmap = array->null_bitmap();
-        auto valid_elements_mda = bit::unpack(validity_bitmap, array_length);
+        auto valid_elements_mda = bit::unpack(validity_bitmap, array_length, array->offset());
         context.outputs[0] = valid_elements_mda;
     }
 

diff --git a/matlab/src/cpp/arrow/matlab/array/proxy/boolean_array.cc b/matlab/src/cpp/arrow/matlab/array/proxy/boolean_array.cc
@@ -53,7 +53,7 @@ namespace arrow::matlab::array::proxy {
         void BooleanArray::toMATLAB(libmexclass::proxy::method::Context& context) {
             auto array_length = array->length();
             auto packed_logical_data_buffer = std::static_pointer_cast<arrow::BooleanArray>(array)->values();
-            auto logical_array_mda = bit::unpack(packed_logical_data_buffer, array_length);
+            auto logical_array_mda = bit::unpack(packed_logical_data_buffer, array_length, array->offset());
             context.outputs[0] = logical_array_mda;
         }
 }
diff --git a/matlab/src/cpp/arrow/matlab/bit/unpack.cc b/matlab/src/cpp/arrow/matlab/bit/unpack.cc
@@ -20,7 +20,7 @@
 #include "arrow/util/bitmap_visit.h"
 
 namespace arrow::matlab::bit {
-    ::matlab::data::TypedArray<bool> unpack(const std::shared_ptr<arrow::Buffer>& packed_buffer, int64_t length) {
+    ::matlab::data::TypedArray<bool> unpack(const std::shared_ptr<arrow::Buffer>& packed_buffer, int64_t length, int64_t start_offset) {
         const auto packed_buffer_ptr = packed_buffer->data();
 
         ::matlab::data::ArrayFactory factory;
@@ -31,7 +31,6 @@ namespace arrow::matlab::bit {
         auto unpacked_buffer_ptr = unpacked_buffer.get();
         auto visitFcn = [&](const bool is_valid) { *unpacked_buffer_ptr++ = is_valid; };
 
-        const int64_t start_offset = 0;
         arrow::internal::VisitBitsUnrolled(packed_buffer_ptr, start_offset, length, visitFcn);
 
         ::matlab::data::TypedArray<bool> unpacked_matlab_logical_Array = factory.createArrayFromBuffer({array_length, 1}, std::move(unpacked_buffer));

diff --git a/matlab/src/cpp/arrow/matlab/bit/unpack.h b/matlab/src/cpp/arrow/matlab/bit/unpack.h
@@ -22,6 +22,6 @@
 #include "MatlabDataArray.hpp"
 
 namespace arrow::matlab::bit {
-    ::matlab::data::TypedArray<bool> unpack(const std::shared_ptr<arrow::Buffer>& packed_buffer, int64_t length);
+    ::matlab::data::TypedArray<bool> unpack(const std::shared_ptr<arrow::Buffer>& packed_buffer, int64_t length, int64_t start_offset);
     const uint8_t* extract_ptr(const ::matlab::data::TypedArray<bool>& unpacked_validity_bitmap);
 }