AST Rule rewriting

Question

I have the following rule and rule rewriting for AST in antlr:

---

param_name
    :   name subscript? initial_value? (',' name subscript? initial_value?)*  ';' -> ^(name subscript? initial_value?)*
    ;   

---

The problem is that i found out that i am not allowed to put a * in the rule rewriting at the place where i have put it. Can anyone suggest a different solution to this? I hope that from my rewritten rule, you can understand what I am trying to achieve.

Answer 1

Try something like this:

grammar T;

...

tokens {
  PARAMS;
}

...

param_names
 : param_name (',' param_name)*  ';' -> ^(PARAMS param_name+)
 ;

param_name
 : name subscript? initial_value? -> ^(name subscript? initial_value?)
 ;

...

If name is an AST as well (opposed to being a single token), you might want to try something like this:

grammar T;

...

tokens {
  PARAMS;
  PARAM;
}

...

param_names
 : param_name (',' param_name)*  ';' -> ^(PARAMS param_name+)
 ;

param_name
 : name subscript? initial_value? -> ^(PARAM name subscript? initial_value?)
 ;

...