AST Walker

    public final void  accept(ASTVisitor visitor) {


        if (visitor == null) {


            throw new IllegalArgumentException();


        }


        // begin with the generic pre-visit


        if (visitor.preVisit2(this)) {


            // dynamic dispatch to internal method for type-specific visit/endVisit

            accept0(visitor);

        }

        // end with the generic post-visit

        visitor.postVisit(this);


    }

abstract void accept0(ASTVisitor visitor);

 

    void accept0(ASTVisitor visitor) {

        boolean visitChildren = visitor.visit(this);

        if (visitChildren) {

            // visit children in normal left to right reading order

            acceptChild(visitor, getException());

            acceptChild(visitor, getBody());

        }

        visitor.endVisit(this);

    }

 

    final void  acceptChild(ASTVisitor visitor, ASTNode child) {

        if (child == null) {

            return;

        }

        child.accept(visitor);

    }