Rich-T-kid opened a new pull request, #10374:
URL: https://github.com/apache/arrow-rs/pull/10374
# Which issue does this PR close?
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- Closes half of #9538.
# Rationale for this change
currently parsing ints and floats with white space prefiing the number
caused the cast to fail
```rust
assert_eq!(Float64Type::parse("\n\t\n\t\n40.5123"), Some(40.5123));
assert_eq!(Float64Type::parse(" 1.5"), Some(1.5));
assert_eq!(Int32Type::parse(" 3"), Some(3));
assert_eq!(Int32Type::parse(" 30"), Some(30));
```
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# What changes are included in this PR?
this PR adds a check to the string before parsing. it checks the first byte,
if its not an ascii digit it will trim the left side of the string.
Performance was a consideration to avoid regressions here — see
https://github.com/apache/arrow-rs/pull/9537#issuecomment-4085626688. In the
worst case where a string doesn't need trimming (no leading whitespace), the
cost is just one slice operation to grab the first byte plus a range comparison
to check if it's an ASCII digit.
benchmarks show no significant change
<img width="1155" height="493" alt="Image 7-18-26 at 1 02 PM"
src="https://github.com/user-attachments/assets/911560a4-bc4f-4dde-83a0-858e4a470bf8";
/>
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# Are these changes tested?
yes. I created a test with 12 assertiosn to validate behavoir
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# Are there any user-facing changes?
yes. arrow-rs/datafusion cast operations will no longer fail when a number
is prefixed with white space.
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