return subtract(first, red1, green1, blue1, alpha1, red2, green2, blue2, alpha2, originalExpression.getUnderlyingStructure());
case PLUS:
return add(red1, green1, blue1, alpha1, red2, green2, blue2, alpha2, originalExpression.getUnderlyingStructure());
default:
throw new BugHappened("Unknown operator.", operator);
}
}