Token – Data Type Conversion

Hidden conversion codes are inserted into the program when a numeric operand needs to be converted to either a double or integer.  However, for numeric constants, no conversion is needed since both the integer and double representation of the constant is available (except for large values that cannot be converted).

The exception mentioned in the last post where the data type of the token is set (excluding token creation) was when a constant is changed or cannot be used because an integer is required but the double is too large (the data type is temporarily changed to the default, which is then checked for by the callers that converts a constant and returns a hidden conversion code for an operand).

The convert constant function was modified to throw an "Expected Valid Integer Constant" status error when an integer is required but the token contains an unconvertible large double constant.  Previously this was up to the caller to check if the expected data type was an integer and a double constant wasn't converted.  Also, instead of setting the data type before calling the table set token code function, the set token code function with the data type arguments is used.

The convert code function was modified to throw "Expected Type Expression" errors when the token cannot be converted to the desired data type.  Only the error Status is thrown and not a Token Error allowing the caller to construct the Token Error.  Previously, this function returned the Invalid Code enumerator, which callers checked for.

The table find code function was modified for this change.  The "Expected Valid Integer Constant" error is thrown from the convert constant function are caught and ignored because it is possible that the operator or function may contain an alternate that takes a double argument (where a large double constant would be acceptable).  If the operator or functions only accepts an integer, then an exception will be throw along with other tokens that cannot be converted.

The translator get expression function was modified to catch error statuses throw from the convert code function and construct a Token Error to throw (by calling the done stack top token error function).  Previously this routine had to check for an unconvertible double constant.  The process done stack top function was similarly modified to catch errors from the table find code function (also previously checking for an unconvertible constant).

The translator get operand function also called the convert code to check the data type of references.  This was not appropriate since no conversion code was needed.  The modified convert code was not throwing appropriate errors for references anyway.  Therefore, a new token is data type compatible access function was added to check the data type only.

The set token code function without a data type argument was an adapter to the set token code passing the data type contained in the token.  Besides the convert constant function, the only other user of this function was the token constructor for string constants, which was modified to use the function with the data type argument directly.  The initializer for the code member was also removed since it get initialized by the set token code function.  The set token code adapter function was removed.

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