tustvold commented on code in PR #3040:
URL: https://github.com/apache/arrow-rs/pull/3040#discussion_r1016054603
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arrow-cast/src/cast.rs:
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@@ -433,34 +434,52 @@ fn cast_reinterpret_arrays<
))
}
-// cast the decimal array to integer array
-macro_rules! cast_decimal_to_integer {
- ($ARRAY:expr, $SCALE : ident, $VALUE_BUILDER: ident, $NATIVE_TYPE : ident,
$DATA_TYPE : expr) => {{
- let array = $ARRAY.as_any().downcast_ref::<Decimal128Array>().unwrap();
- let mut value_builder = $VALUE_BUILDER::with_capacity(array.len());
- let div: i128 = 10_i128.pow(*$SCALE as u32);
- let min_bound = ($NATIVE_TYPE::MIN) as i128;
- let max_bound = ($NATIVE_TYPE::MAX) as i128;
- for i in 0..array.len() {
- if array.is_null(i) {
- value_builder.append_null();
+fn cast_decimal_to_integer<D, T>(
+ array: &ArrayRef,
+ base: D::Native,
+ scale: u8,
+ max_bound: D::Native,
+ min_bound: D::Native,
+) -> Result<ArrayRef, ArrowError>
+where
+ T: ArrowPrimitiveType,
+ <T as ArrowPrimitiveType>::Native: NumCast,
+ D: DecimalType + ArrowPrimitiveType,
+ <D as ArrowPrimitiveType>::Native: ArrowNativeTypeOp + ToPrimitive,
+{
+ let array = array.as_any().downcast_ref::<PrimitiveArray<D>>().unwrap();
+
+ let div: D::Native = base.pow_checked(scale as u32).map_err(|_| {
+ ArrowError::CastError(format!(
+ "Cannot cast to {:?}. The scale {} causes overflow.",
+ D::PREFIX,
+ scale,
+ ))
+ })?;
+
+ let mut value_builder = PrimitiveBuilder::<T>::with_capacity(array.len());
+ for i in 0..array.len() {
+ if array.is_null(i) {
+ value_builder.append_null();
+ } else {
+ let v = array.value(i).div_checked(div)?;
+
+ // check the overflow
+ // For example: Decimal(128,10,0) as i8
Review Comment:
Can we just use `append_option(NumCast::from(v))` and eliminate the bounds
checks from this code?
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