Is there any tool to desugar G4 format to a normal LL(*) format.

[ghost]

I learn about that antlr4 is also a variant of LL(*) parser generator and the LL(*) grammar cannot deal with left-recursion, even direct left-recursion. The G4 format can express the left-recursive grammar, so there must be some sugar right?

If so, is there any tool to convert G4 format to a non-left-recursive grammar, e.g. LL(*) format.

[kaby76]

I learn about that antlr4 is also a variant of LL() parser generator and the LL() grammar cannot deal with left-recursion, even direct left-recursion. The G4 format can express the left-recursive grammar, so there must be some sugar right?

If so, is there any tool to convert G4 format to a non-left-recursive grammar, e.g. LL(*) format.

At one point, I had a tool that removed direct-left recursion using the usual procedure outlined in the Dragon Book. It also converted recursions into kleene closures, which is different than removing direct-left recursion. I can't tell which you are looking for. Unfortunately, I haven't updated the tool when I rewrote the use of Antlr parse trees into something much more efficient for editing, and would need to be redone to separate the two refactorings, and offer the inverse refactoring.

[kaby76]

I just found this website, and will create a list of useful grammar-related websites, including these. https://cyberzhg.github.io/toolbox/left_rec

[ghost]

Wow, awesome websites. Thanks a lot, it really helps me.