Translator – Commands (Introduction)

Now that expressions have been fully implemented in the Translator (at least until more language features are added), it's time to start implementing the BASIC commands. In fact, one command has already been implemented, the assignment statement without the optional LET keyword.

It was mentioned some time ago that there was a way to eliminate the need for the dummy close parentheses codes. These dummy codes are put into the translated output where unnecessary parentheses were entered into an expression, so that the Recreator would know to reproduce them. This will prevent confusion from having entered parentheses just disappear. During run-time, these dummy codes would be skipped.

It turns the same method to get rid of these dummy parentheses codes will also be used for the LET command, first command to be implemented. There are already 8 assignment codes, and there will be 4 more once temporary strings are fully implemented in the Encoder. All of these assignment codes are for without the optional LET. Either another dummy code is needed for the LET or each of the assignment operator needs to duplicated when the optional LET is included – that's 12 more codes.

Neither of these two alternatives is desirable. There is a third alternative that will help eliminate the need for these dummy codes, but some look ahead planning is required into the design of the format for how the BASIC program code will be stored internally. In fact, as each BASIC command is implemented, so forward planning is necessary into how the command will be stored in memory and executed during run-time. Next a preliminary design of the internal code...