allow double bang (double boolean_not)

[tinygiant98]

Allows double boolean_not (!!x) without requiring the second booelan_not to be enclosed in parenthesis (i.e. !(!x)).

Testing

Tested the following use cases:

• Single bang (boolean_not) -> !x
• Double bang -> !!x
• Parenthesized double bang -> !(!x)
• Multiple bangs -> !!!x
• Passed as a parameter -> my_function(!!x)

Changelog

Added

• Allow use of double-bang to "booleanize" a constant/variable integer value without requiring the second boolean negation to be parenthesized.

Licence

• I am licencing my change under the project's MIT licence, including all changes to GPL-3.0 licenced parts of the codebase.

[tinygiant98]

Exceptionally minor changes could also allow the following constructs, but I didn't add them in because they could be useless/confusing/undesired:

• Double unary negation (- -7)
• Boolean_not followed by decrement (!--)
• Boolean_not followed by increment (!++)

If anyone thinks these would be useful/desireable, I can add them in.