Translator – First/Last Operand – More on Parentheses

An old undiscovered bug was found where the pending parentheses token was not deleted when the previous token added to the output list's parentheses sub-code was set when it was determined that the parentheses was not necessary (the parentheses sub-code allows the parentheses to be reproduced). This again emphasizes the need for memory leak detection (more on this soon).

There was a conflict between a closing parentheses token being used as a pending parentheses and as a last operand. It's possible that a pending parentheses will become a token added to the output list (occurs when there are two sets of unnecessary parentheses), so when this token is no longer needed as a last operand, it can't be deleted. The solution was for two new sub-codes, one where the closing parentheses token is being used for a pending parentheses (Used) and one where it is being used for a last operand (Last).

When the pending parentheses is set, the token's Used sub-code is set. When a closing parentheses token is set as a last operand, the token's Last sub-code is set. When the pending parentheses token is no longer needed, if its Last sub-code is set, the Used sub-code will be cleared, otherwise the token will be deleted. If the pending parentheses is added to the output, its Used sub-code will be left set to prevent it from getting deleted. Similarly, when a closing parentheses token is no longer needed as a last operand, if its Used sub-code is set, its Last sub-code will be cleared, otherwise the token will be deleted.

In the closing parentheses handler, when a closing parentheses is processed for a parenthetical expression, the opening parentheses (previously deleted) will now be set as the first operand and the closing parentheses (also set to the pending parentheses) will not be set as the last operand of the token on top of the done stack. The closing parentheses token's Last and Used sub-codes will be set.