xiazcy opened a new pull request, #3616:
URL: https://github.com/apache/tinkerpop/pull/3616
## Summary
Fixes a non-deterministic type-safety hole in `SumLocalStep` and documents
the `Scope.local` boxing semantics in the
provider semantics specification.
## Problem
`sum(local)` on a single non-numeric scalar (e.g.
`g.inject("hello").sum(local)`) would non-deterministically either
throw `ClassCastException` or pass the value through as identity,
depending on JIT compilation state. This is because
the generic bound `E extends Number` is erased at runtime, and the
arithmetic call that would enforce it
(`NumberHelper.add`) is only reached when there are 2+ elements.
`mean(local)` was already correct (always calls
`div()`), while `min(local)`/`max(local)` are unaffected (they use
`Comparable` bounds, and `NumberHelper.min/max`
correctly falls back to `compareTo` for non-Numbers).
## Fix
Added an explicit `instanceof Number` check in `SumLocalStep` after
`untilNonNull()` returns the first element, making
the error deterministic.
## Documentation
Added a "Local scope and single values" section
(`[[gremlin-semantics-local-scope-boxing]]`) to
`gremlin-semantics.asciidoc` specifying:
- The wrapping dispatch (LIST/SET/array/MAP iterate directly; anything
else wraps to a single-element sequence)
- Scalar numeric identity behavior (`sum(local)` on `29` → `29`)
- Type error contract for incompatible input (regardless of collection
size)
## Tests
- **Gherkin** (`Sum.feature`): `sum(local)` on a non-numeric list (error)
and a single non-numeric scalar (error),
with GLV translations for .NET, Go, JS, Python
- **Unit** (`SumLocalStepTest`): numeric scalar identity + non-numeric
error
- **Unit** (`MeanLocalStepTest`): numeric scalar identity + non-numeric
error
- **Unit** (`MinLocalStepTest`): numeric identity, String identity (valid
Comparable), String-list min, numeric-list
min
- **Unit** (`MaxLocalStepTest`): numeric identity, String identity,
String-list max, numeric-list max
- **Unit** (`IteratorUtilsTest`): Number singleton wrapping + generic
Object singleton wrapping
---
VOTE +1
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