tustvold commented on code in PR #3021:
URL: https://github.com/apache/arrow-rs/pull/3021#discussion_r1014728749
##########
arrow-cast/src/cast.rs:
##########
@@ -344,16 +344,50 @@ fn cast_floating_point_to_decimal128<T:
ArrowPrimitiveType>(
array: &PrimitiveArray<T>,
precision: u8,
scale: u8,
+ cast_options: &CastOptions,
) -> Result<ArrayRef, ArrowError>
where
<T as ArrowPrimitiveType>::Native: AsPrimitive<f64>,
{
let mul = 10_f64.powi(scale as i32);
- array
- .unary::<_, Decimal128Type>(|v| (v.as_() * mul).round() as i128)
- .with_precision_and_scale(precision, scale)
- .map(|a| Arc::new(a) as ArrayRef)
+ if cast_options.safe {
+ let iter = array.iter().map(|v| {
+ v.and_then(|v| {
+ let mul_v = (mul * v.as_()).round();
+ if mul_v == f64::INFINITY || mul_v == f64::NEG_INFINITY {
+ None
+ } else {
+ Some(mul_v as i128)
+ }
+ })
+ });
+ let casted_array =
+ unsafe {
PrimitiveArray::<Decimal128Type>::from_trusted_len_iter(iter) };
+ casted_array
+ .with_precision_and_scale(precision, scale)
+ .map(|a| Arc::new(a) as ArrayRef)
+ } else {
+ array
+ .try_unary::<_, Decimal128Type, _>(|v| {
+ mul.mul_checked(v.as_()).and_then(|value| {
+ let mul_v = value.round();
+ if mul_v == f64::INFINITY || mul_v == f64::NEG_INFINITY {
+ Err(ArrowError::CastError(format!(
+ "Cannot cast to {}({}, {}). Overflowing on {:?}",
+ Decimal128Type::PREFIX,
+ precision,
+ scale,
+ v
+ )))
+ } else {
+ Ok(mul_v as i128)
Review Comment:
I'm still confused as to how this can't overflow?
If the float value was i128::MAX any scale greater than 1 would result in
this conversion overflowing?
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