fixing lexing to support static invariants

[mattulbrich]

Intended Change

This pull request includes a change to the IMPLICIT_IDENT rule in the KeYLexer.g4 file to allow an optional dollar sign before the letter sequence.

Lexer rule modification:

• key.core/src/main/antlr4/KeYLexer.g4: Modified the IMPLICIT_IDENT rule to accept an optional dollar sign ('<) before the letter sequence.

The reason is that static invariants are represented as Classname::<$inv> which one was not able to use in a manual cut.

But valid key terms should be parseable.

Plan

It is only a 4 character fix allowing implicit identifiers to start with a $.

Type of pull request

• Bug fix (non-breaking tiny change which fixes an issue)

Ensuring quality

n/a

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.

[WolframPfeifer]

I am not really a fan of the constructs o.<inv> and C.<$inv>. I wondered whether it would be a good idea to use something like C.class.<inv> for the latter. That would be at least one special construct less, and be closer to Java and the developer perspective ...