Translator – Assignments (New Implementation)

The new implementation of assignment statements consist of removing the existing code list assignment processing from the add operator routine and adding processing to the equal token handler, comma token handler and the assign command handler (which currently does nothing).

Comma: When the first comma token is received, the data type of the assignment is set to the first assignment item and an assign list code appropriate for the item's data type is pushed to the command stack instead of pushing the main assign list code to the hold stack. If there is a LET command already on the command stack, it will be replaced with the assign list code.

For each additional comma token, the data type of the assignment item will be checked to make sure it matches the current data type. If the data type is a string or sub-string and the new item's data type is also a string or sub-string, but not the same, the assign list code will be changed to the AssignListMixStr code. When an equal token is received in the comma assignment, the mode is set to expression after the last list assignment item is checked and the expression type is changed to Numeric or String.

Equal: When an equal token is received first, the data type of the assignment is set to the assignment item and an assign code appropriate for the item's data type is pushed to the command stack instead of the hold stack. If there is a LET command already on the command stack, it will be replaced with the assign code. The expression type is changed to Numeric or String in case the expression starts after the equal.

If a second equal token is received, the assign token on top of the command stack is changed to the appropriate assign list code. For each additional equal token, the data type of the assignment item will be checked to make sure it matches the current data type. The same check for strings made for each additional comma token is also made for each additional equal.

I realized that it is not necessary to save string variables in assignment and list assignment statements – it is already known these operands will not be temporary strings. Only a string value needs to be saved for string assignments as it may be a temporary string. Also, the Translator can identify some strings as temporaries (the result of the concatenate operator and all but the sub-string internal functions that return a string). Modifying the Translator for these temporary strings will be done after the INPUT command is implemented.