New Translator – Internal Functions

To support internal functions, both with arguments (parentheses) and without (no parentheses), the get operand function was updated.  Internal functions without arguments are treated the same as constants and identifiers with no parentheses where the tokens are simply added to the RPN output list and pushed to the done stack.

For internal functions with parentheses, a new get internal function routine was implemented and called.  This function starts by pushing the internal function token to the hold stack, which being of low precedence, will create a border as the expressions of the arguments are processed.  After getting the number arguments, it loops for each argument by first calling the get expression routine and then checking the terminating token for a comma or closing parentheses.

For a comma, if at the last argument, then an error is returned if the internal function code does not have multiple entries (for examine, the MID$ function with two or three arguments).  Otherwise the code is changed to the code with an additional argument.  The comma token is deleted and the existing find code routine is called to process and check the argument.

For a closing parentheses, if not at the last argument, then an error is returned.  Otherwise the existing process final operand function is called to process the final argument, which appends the internal function token to the RPN output list upon success.  The internal function token is then dropped from the hold stack.

If the terminating token is neither a comma nor a closing parentheses, then the appropriate error is returned depending which argument it is at taking into account whether the internal function has multiple entries.

Expression test #3 now passes with the new translator routines except for the three lines that contain identifiers with parentheses (an array or a user function), which has not yet been implemented in the new translator.  Expression test #4 also now passes successfully.  Since none of the expression tests contained a function with no arguments, a new expression was added to test #4 containing the RND function.

[commit 81d3137531]

New Translator – Checking Token Codes

A minor coding issue was discovered in code that needs to check the code in a token.  This is more an issue with the new translator routines because they will be checking tokens that could be of any token type.  The old translator routines already knew the token type before checking the code.

Since it is desirable to make the code as easy to implement as possible, the Token class isCode() function was modified to make sure the token is the correct type before checking the code.  The correct type is any type that has a table entry.  If the calling code already knows the token is a type that has a valid code, then it can use the Token class code() access function and compare to the code directly.

[commit 9bbd1e319f]