simpleqt opened a new pull request, #421:
URL: https://github.com/apache/commons-jexl/pull/421
`JexlArithmetic.isEmpty(Object, Boolean)` tests a `Number` for emptiness by
converting it to a `double` and comparing with zero
(`JexlArithmetic.java:1116-1119`):
```java
final double d = ((Number) object).doubleValue();
return Double.isNaN(d) || d == 0.d;
```
`BigDecimal` and `BigInteger` are unbounded, so a non-zero value whose
magnitude is below `Double.MIN_VALUE` underflows to `0.0` and is reported as
empty although it is not zero:
```java
final JexlScript s = new JexlBuilder().create().createScript("empty(x)",
"x");
s.execute(null, new BigDecimal("1E-400")); // true, expected false
s.execute(null, new BigDecimal("-1E-400")); // true, expected false
```
`empty x` (the unary operator) behaves the same, and the value is not zero
by any measure: `signum()` is non-zero, `compareTo(BigDecimal.ZERO)` is
positive, and arithmetic keeps it alive (`1E-400 + 1E-400 == 2E-400`). Only
`BigDecimal`/`BigInteger` reach this: every bounded `Number` (including `Long`,
whose identical defect was JEXL-163) fits in a `double`, so the conversion is
lossless enough there. The same double comparison was also incidental for
magnitudes above `Double.MAX_VALUE`, where the conversion yields an infinity
that happened to be non-empty.
Fix: use the sign of the unbounded number, `signum() == 0`, for `BigDecimal`
and `BigInteger`; all other `Number` types keep the existing double-based test,
so zero values, `Double.NaN` and the `AtomicInteger`/`AtomicLong` behavior are
unchanged.
Validation:
- New test `ArithmeticTest#testEmptyBigNumberMagnitudes` covers `1E-400`,
`1E-320`, `-1E-400`, `1E400`, `1E5000`, `BigInteger("-1")` as non-empty and
`0`, `0E-400`, `0.0000`, `BigInteger.ZERO` as empty, through `empty(x)`, `empty
x` and `x.empty()`.
- It fails on the pre-fix base (`expected: <false> but was: <true>`) and
passes with the fix.
- Full `mvn test` passes: 1216 tests, 0 failures; checkstyle reports 0
violations.
No `src/changes/changes.xml` entry is included because the action format
requires a JIRA issue key and I do not have a JIRA account. Happy to add one,
e.g.:
```xml
<action dev="simpleqt" due-to="simpleqt" type="fix" issue="JEXL-xxx">empty()
now considers a non-zero BigDecimal or BigInteger with a magnitude outside the
double range as non-empty.</action>
```
AI assistance used to diagnose and fix this defect; the analysis and the
change have been reviewed and verified as described above.
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