Translator – Data Types On Assignments

The assignment operators need a little bit different handling that regular operators because they require reference tokens for the operands being assigned. The reference tokens will have a specific data type and can not be converted between types. Only the value being assigned can be converted to the type of the reference operands. An added complication with the assignment list operators is that they have no set number of reference operands so the number of operands and the operand data types in the table entries will not work, which the match code routine relies on.

To support the assignment operator, the match code routine needs to be modified so that when it sees a reference operand, to only check if the data type matches exactly to the data type in the table entry. The main assignment operator (Assign, which will handle the double data type) will have two associated codes, AssignInt and AssignStr. The second operand for Assign and AssignInt can be converted.

For the assignment list operators, it has already been decided that all of the variables being assigned must be the same data type, in other words, no mixing of doubles and integers – mainly for efficiency during run-time. The match code routine was not designed to handle a variable number of operands for a code. However, the match code routine can be used, at least to check the two operands on top of the done stack, which would be the value being assigned and the last reference operand in the list being assigned.

In the add operator routine, upon returning from the match code routine successfully, it can then check if the operator is an assignment list operator. This can be accomplish with a new assignment list operator flag in the table entry. If this flag is set, then the add routine would proceed to check the rest of the operands on the done stack for the reference flag (which it does now) and check to see if the data type is the same as the assignment list operator returned from the match code routine.