Extend Antlr grammar file with lists

Question

I have the following assignment about extending an Antlr grammar.

What I've tried is:

I am not sure whether this is the correct solution or not. Can anyone guide me in the right direction?

Answer 1

2 problems here: 1) you have 2 the same alt-labels (# Lists), and 2) you only allow zero or a single expression in your list. It should be this:

expr
 : ...
 | '(' expr ')'                    # Parenthesis
 | '[' ( expr ( ',' expr )* )? ']' # Lists
 ;