Translator – Expression Types and Unary Operators

Unary operators only have one operand, so do not have a first operand. In fact, any errors reported at the unary operator sub-expression, should point to the unary operator, not it's operand (unless the operand has an error). Therefore, the first operand is only attached to a binary operator pushed to the done stack. The first operand token will be set to the default value of NULL for a unary operator.