Forming an AST node for a sequence or list

Greetings,
        I have a couple of grammar elements of the following form:


A -> Ab | b ( or in yacc form A : A "b" | "b"; )


I am planning to form strings matched by this type of rule into AST
nodes that look like this (given the input string "bbb"):-


                    A
                  /|\
                b b b


I plan on representing list of statements this way and also comma
separated lists of function arguments.


I have two questions.


(1) Is this a reasonable form for the AST node representing the
abovementioned sequences?


(2) How do I write the semantic actions to acheive the desire tree
shape?


This is my guess. It isn't real code.


A : A "b" {
                                if ( $$ == NULL ) {
                                        /* Make a new A and attach new leaf b */
                                        $$ = makeNode( A_NODE, makeLeaf( $2 ) ) ;
                                } else {
                                        /* 'A' already exists so just attach new leaf b */
                                        addChild( $$, makeleaf( $2 ) )
                                }
                        }
      | "b" {
                                if ( $$ == NULL ) {
                                        $$ = makeNode( A_NODE, makeLeaf( $1 ) ) ;
                                } else {
                                        addChild( $$, makeLeaf( $1 ) ) ;
                                }
                        }
      ;


Any help or comments would be greatly appreciated.


Cheers,
              Jeff

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