Pattern for mode in multimode lexer

[dhowe]

I'm sure this is quite simple, but I have a mode that should start with @{ and end with }@, and should accept anything else inside including }. My tokens are as below. How would I define the pattern for my Gate token ?

 const EnterGate = createToken({
    name: "EnterGate",
    pattern: /@{/
    push_mode: "gate_mode"
  });

  const ExitGate = createToken({
    name: "ExitGate",
    pattern: /}@/
    pop_mode: true
  });

  const Gate = createToken({
    name: "Gate",
    pattern: ??
  });

[msujew]

You can probably use something like (?:(?!}@).)*. It uses a negative lookahead group (?!) to prevent matching }@ and then attempts to match any character .. This is repeating until it arrives at the end of the input or the }@ sequence.

[dhowe]

Thanks, though actually I'm thinking a better option might be to start with @{ and end the mode when that open bracket is matched with a closing }. How to keep track of the bracket matching, given that there may be other nested pairs within ?

Perhaps I should open a separate discussion ticket for this?

[matthew-dean]

you'll probably want ORs that are recursive... as in, it can be a value OR an opening LParen, for example, and then your original rule (that you're currently in) and THEN a closing RParen