Friday, April 23, 2010

Translator – Operand Data Types

Now it has been established that operators and internal functions can be handled the same way, except that the number of arguments (operands) is checked first for internal functions. For internal functions, the number of arguments check also determines which code to use (MID2 vs. MID3, INSTR2 vs. INSTR3, or ASC vs. ASC2).

Each code (operator or internal function) has a return data type, a fixed number of operands and a expected data type for each operand. The word operand will be used instead of argument from now on, which  is more appropriate when applied to operators. Taking the plus operator as an example, which will have three codes (one main and two associated codes):
Add  Double  (2)  Double  Double
AddInt  Integer  (2)  Integer  Integer
CatStr  String  (2)  String  String
The code is listed first along with the return data type. The number of operands is in parentheses followed by the data type of each operand. If there is an add with a double and an integer operand, the Add code will be used with a CvtInt inserted after the integer operand.

The table entries already contain the code and data type values and the number of arguments will be renamed to the number of operands. A new operand data type array needs to be added to the table entries. The size of this array will be set to three since there are currently no planned functions containing more than three arguments. Next, how associated codes will be handled...

No comments:

Post a Comment

All comments and feedback welcomed, whether positive or negative.
(Anonymous comments are allowed, but comments with URL links or unrelated comments will be removed.)