SEPURI-SAI-KRISHNA opened a new pull request, #12737:
URL: https://github.com/apache/maven/pull/12737
Fixes #12736
### What
Adds handling for the `!` operator to `ConditionParser.parseUnary()`.
### Why
The tokenizer already treats `!` as an operator and emits a bare `!` token,
but no parser rule
consumes it. Writing the natural form of a negated condition:
```xml
<condition>!exists('some/path')</condition>
```
fails with `Unknown variable: !`, which is confusing — nothing in the
expression is a variable.
`!` is defined here as sugar for the `not()` function that already exists,
using the same
`toBoolean()` coercion, so this adds no new capability and no new semantics.
It is handled in
`parseUnary()`, giving it the same precedence as in Java: tighter than
arithmetic, comparison,
`&&` and `||`.
`!=` is unaffected — the tokenizer emits it as a single token before a bare
`!` can be produced.
### Tests
Four tests added to `ConditionParserTest`, all failing before the change:
- `testLogicalNotOperator` — basic negation, stacking (`!!`, `!!!`), and
negating a function call
- `testLogicalNotOperatorMatchesNotFunction` — pins `!x` to the same result
as `not(x)`
- `testLogicalNotOperatorPrecedence` — precedence against `&&`, `||` and
parenthesised groups
- `testLogicalNotOperatorCoercion` — string/number coercion matches `not()`
The negation tests deliberately use `contains('Hello, World!', ..)`, which
puts a `!` inside a
string literal, to confirm the tokenizer still leaves quoted `!` alone.
---
## Out of scope — a separate bug found while testing this
`compare()` handles `Number` vs `Number` and `String` vs `String`, but has
no `Boolean` branch, so
comparing two booleans throws on the **unmodified** parser:
```
true == true => RuntimeException: Cannot compare true and true with
operator ==
true != false => RuntimeException: Cannot compare true and false with
operator !=
```
This is pre-existing and independent of `!`. It is deliberately NOT fixed in
this PR, and the
tests here avoid boolean-to-boolean comparison. Candidate for a fourth PR.
---
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