[GitHub] [arrow] kiszk commented on a change in pull request #8955: ARROW-9948: [C++] in Decimal128::FromString raise when scale is out of bounds

[GitBox <gi...@apache.org>]

kiszk commented on a change in pull request #8955:
URL: https://github.com/apache/arrow/pull/8955#discussion_r546328882



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File path: cpp/src/arrow/util/basic_decimal.cc
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@@ -949,33 +949,31 @@ DecimalStatus BasicDecimal128::Rescale(int32_t original_scale, int32_t new_scale
 
 void BasicDecimal128::GetWholeAndFraction(int scale, BasicDecimal128* whole,
                                           BasicDecimal128* fraction) const {
-  DCHECK_GE(scale, 0);
-  DCHECK_LE(scale, 38);
+  DCHECK_EQ(ValidateScale(scale), true);
 
   BasicDecimal128 multiplier(ScaleMultipliers[scale]);
   auto s = Divide(multiplier, whole, fraction);
   DCHECK_EQ(s, DecimalStatus::kSuccess);
 }
 
+bool BasicDecimal128::ValidateScale(int32_t scale) { return (std::abs(scale) <= 38); }

Review comment:
       This function can accept `-38 <= scale <= 38` while the original code accepted `0 <= scale <= 38`.   
   Is this change expected? If so, it would be good to leave a comment.




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