Function ArrayToVarcharCast

src/function/cast/array_casts.cpp:94–162

------------------------------------------------------------------------------ ARRAY -> VARCHAR ------------------------------------------------------------------------------

// ARRAY -> VARCHAR
//------------------------------------------------------------------------------
static bool ArrayToVarcharCast(Vector &source, Vector &result, idx_t count, CastParameters &parameters) {
	auto is_constant = source.GetVectorType() == VectorType::CONSTANT_VECTOR;

	auto size = ArrayType::GetSize(source.GetType());
	Vector varchar_list(LogicalType::ARRAY(LogicalType::VARCHAR, size), count);
	ArrayToArrayCast(source, varchar_list, count, parameters);

	varchar_list.Flatten(count);
	auto &validity = FlatVector::Validity(varchar_list);
	auto &child = ArrayVector::GetEntry(varchar_list);

	child.Flatten(count);
	auto &child_validity = FlatVector::Validity(child);

	auto in_data = FlatVector::GetData<string_t>(child);
	auto out_data = FlatVector::GetData<string_t>(result);

	static constexpr const idx_t SEP_LENGTH = 2;
	static constexpr const idx_t NULL_LENGTH = 4;

	for (idx_t i = 0; i < count; i++) {
		if (!validity.RowIsValid(i)) {
			FlatVector::SetNull(result, i, true);
			continue;
		}

		// First pass, compute the length
		idx_t array_varchar_length = 2;
		for (idx_t j = 0; j < size; j++) {
			auto elem_idx = (i * size) + j;
			auto elem = in_data[elem_idx];
			if (j > 0) {
				array_varchar_length += SEP_LENGTH;
			}
			array_varchar_length += child_validity.RowIsValid(elem_idx) ? elem.GetSize() : NULL_LENGTH;
		}

		out_data[i] = StringVector::EmptyString(result, array_varchar_length);
		auto dataptr = out_data[i].GetDataWriteable();
		idx_t offset = 0;
		dataptr[offset++] = '[';

		// Second pass, write the actual data
		for (idx_t j = 0; j < size; j++) {
			auto elem_idx = (i * size) + j;
			auto elem = in_data[elem_idx];
			if (j > 0) {
				memcpy(dataptr + offset, ", ", SEP_LENGTH);
				offset += SEP_LENGTH;
			}
			if (child_validity.RowIsValid(elem_idx)) {
				auto len = elem.GetSize();
				memcpy(dataptr + offset, elem.GetData(), len);
				offset += len;
			} else {
				memcpy(dataptr + offset, "NULL", NULL_LENGTH);
				offset += NULL_LENGTH;
			}