pitrou commented on code in PR #43957:
URL: https://github.com/apache/arrow/pull/43957#discussion_r1763368294
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cpp/src/arrow/testing/random.cc:
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@@ -343,8 +343,72 @@ struct DecimalGenerator {
}
};
+template <typename DecimalType>
+struct SmallDecimalGenerator {
+ using DecimalBuilderType = typename TypeTraits<DecimalType>::BuilderType;
+ using DecimalValue = typename DecimalBuilderType::ValueType;
+ using IntegerType = typename DecimalValue::ValueType;
+ using IntArrowType = typename CTypeTraits<IntegerType>::ArrowType;
+
+ std::shared_ptr<DataType> type_;
+ RandomArrayGenerator* rng_;
+
+ static IntegerType MaxDecimalInteger(int32_t digits) {
+ return static_cast<IntegerType>(std::ceil(std::pow(10.0, digits))) - 1;
+ }
+
+ std::shared_ptr<Array> MakeRandomArray(int64_t size, double null_probability,
+ int64_t alignment, MemoryPool*
memory_pool) {
+ static constexpr int32_t kMaxDigitsInInteger =
+ std::is_same_v<DecimalType, Decimal32Type> ? 9 : 18;
+ static_assert(
+ kMaxDigitsInInteger >= DecimalType::kByteWidth,
+ "inconsistent decimal metadata: kMaxPrecision doesn't match
kByteWidth");
+
+ const auto& decimal_type = checked_cast<const DecimalType&>(*type_);
+
+ auto digits_to_generate = decimal_type.precision();
+ auto values = checked_pointer_cast<typename
TypeTraits<IntArrowType>::ArrayType>(
+ rng_->Numeric<IntArrowType>(size, -1 *
MaxDecimalInteger(digits_to_generate),
+ MaxDecimalInteger(digits_to_generate),
+ null_probability, alignment, memory_pool));
+
Review Comment:
Note that we could just reuse the buffers, or perhaps even return
`values.View(decimal_type)`.
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