Translator – Parentheses (Recreation Issue)

When expressions with parentheses are translated to RPN, parentheses get removed as they are not necessary. Instead, RPN is dependent on the order of the expression. This is why RPN calculators have no parentheses keys like regular calculators. Take the expressions (A*B)+C and A*B+C – both would be translated to A B * C + (in other words, the parentheses are unnecessary in the original expression).

One of my pet peeves with programmers are the addition of unnecessary parentheses into expressions when they are not needed (my opinion: learn and use the language properly). It would be easy to just let the parentheses disappear as occurs automatically when an expression is translated to RPN, as would happen when the expression above is recreated since the expression is equivalent without parentheses. Unlike, for the expression (A+B)*C, that would be translated to A B + C *; the parentheses would be added back when the expression is recreated, because the parentheses are needed or the meaning of the expression would be changed.

However, it would unexpected to a programmer for the parentheses to just disappear. This is the reason that the original strings of numeric constants are being kept in tokens. It would not be nice for a number to be entered as 0.000001, but show up as 1e-6 in the program. To keep these unnecessary parentheses in the code so that they will be in the recreated expression, something needs to be added to the internal code. However, it would just waste memory and run-time to just throw in parentheses everywhere they are entered. So for these unnecessary cases, a dummy token will be added to the RPN list and since the closing parentheses token is present, this token will be the token added. During run-time, the closing parentheses code will be a no-operation code.

Note that no-operation does not mean no execution time, some processing will be required to skip over the dummy code; which is why dummy parentheses tokens won't be put into the code everywhere there are parentheses in the original expressions.  Later an option will be added to allow the user the option of having parentheses removed automatically. This will give the user the choice. Now the trick is to decide when to add one of these dummy tokens and when not to...