Translation – INPUT and Error Reporting

Upon designing the actions required by the add input codes routine, I realized that it may need to point to a different token when an error is detected. Consider this example:

INPUT PROMPT A;B

The error will be “expected string expression” and should be pointing to the A, but the current token being processed is the semicolon token. Therefore, instead of passing the token code of the token being processed, a reference to the token pointer will be passed so that it can be changed to point to the actual token with the error.

For The INPUT command handler (called at end of statement tokens), a Colon code was going to be passed regardless of the actual end of statement token, but now a reference to a token pointer will be passed. This will be whatever end of statement token, which was passed to the INPUT command handler and will be passed on to the add input codes routine.

This led to another problem, consider this example:

INPUT PROMPT A*B+C;D

The + operator will be on top of the done stack after the expression is processed, so the error will be pointing to + since it will have the double data type. The error should be pointing to the A indicating that a string expression was expected. This problem applies to other statements as well, so some sort of expression type detection is needed...