예제 #1
0
        internal override bool Nullable()
        {
            switch (contentType)
            {
            case Type.Sequence:
                return(left.Nullable() && right.Nullable());

            case Type.Choice:
                return(left.Nullable() || right.Nullable());

            case Type.Plus:
                return(left.Nullable());

            default:
                return(true);     // Type.Qmark, or Type.Star
            }
        }