pitrou commented on code in PR #52451:
URL: https://github.com/apache/arrow/pull/52451#discussion_r4259032996
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cpp/src/arrow/compute/kernels/scalar_string_ascii.cc:
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@@ -2642,7 +2642,8 @@ struct SliceBytesTransform : StringSliceTransformBase {
// on the resulting slice lengths, so return a worst case estimate.
return input_bytes;
}
- int64_t max_slice_bytes = (opt.stop - opt.start + opt.step - 1) / opt.step;
+ const int64_t stop = std::clamp(opt.stop, -input_bytes, input_bytes);
Review Comment:
Can you add a comment explaining the motivation for this?
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cpp/src/arrow/compute/kernels/scalar_string_test.cc:
##########
@@ -2702,6 +2702,13 @@ TYPED_TEST(TestBinaryKernels, SliceBytesBasic) {
}
TYPED_TEST(TestBinaryKernels, SliceBytesPosPos) {
+ SliceOptions options_default_stop{/*start=*/1};
+ const std::string long_input(300, 'x');
+ this->CheckUnary(
+ "binary_slice", this->template MakeArray<std::string>({"abcdef",
long_input}),
+ this->template MakeArray<std::string>({"bcdef", std::string(299, 'x')}),
+ &options_default_stop);
Review Comment:
I think we can add a couple other interesting cases:
* start=1, step=5
* start=-1, stop=INT64_MIN
* start=-1, stop=INT64_MIN, step=-5
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