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antlrworksantlr4

Choice left element with multiple (+) quantifier does not become an array

A fragment of my grammar is:

potentialAttribute: DATA EQUAL LEFTPARENTH (data+ | REAL+) RIGHTPARENTH SEMICOLON;

Then, in visitor, I should ask potentialAttribute if text read was data+ or REAL+. Since both of them have + symbol, both must be arrays. Nevertheless, only REAL() is a List<TerminalNode>, while data() remains as TerminalNode.

BUT if I change choice order, like:

potentialAttribute: DATA EQUAL LEFTPARENTH (REAL+ | data+) RIGHTPARENTH SEMICOLON;

It is REAL the one which does not work.

What can cause this?

(I can post the whole compilable code if needed)

Solution

  • This would be a bug in ANTLR 4. You can report issues to the project issue tracker on GitHub:

    https://github.com/antlr/antlr4/issues