In my tree parser, I have the following:

! statement:

: #(NEG s:statement)

{ if(s.getType() == CON){

AST t = s.getFirstChild();

AST left = #([NEG],t);

			AST right = #([NEG],t.getNextSibling());
			

		

#statement = #([DIS],left,right);

}

;

: #(CON l:statement r:statement)

{ ....... }

;

Is there a way that I can make these alterations to the tree before the subtree is acted on by the recursive tree parser?