[antlr-interest] Transform postfix_expression in C grammar to AST

[Xiao Jia]

Hi,

I'm learning ANTLR by modifying the C grammar and trying something interests
myself. The C grammar I started with is from:
http://www.antlr.org/grammar/1153358328744/C.g

Now I want to transform postfix_expression to its corresponding AST but
haven't known anything related to the transformation of the form xx
(aa|bb|cc)* yy

...
unary_expression
  : postfix_expression
  | unary_operator*^* unary_expression
  ;

postfix_expression
  : primary_expression
  ( '[' expression ']'
  | '(' ')'
  | '(' argument_expression_list ')'
  | '.' ID
  )*
  ;

unary_operator
  : '+'
  | '-'
  | '~'
  | '!'
  ;
...

Can you help me with this?

Thanks,
Xiao Jia