Translator – Internal Functions

The Translator is unable to check the number of operands for arrays or functions without more information – information that will be contained in the Dictionary, so this checking will be left for the Encoder. However, the number of arguments for internal functions are fixed and can be checked within the Translator.

The number of arguments cannot be checked with knowing the number, therefore a new number of arguments member needs to be added to the Table entries. However, some internal functions may have more than one form. Several of these types or functions are currently planned, which include MID$, ASC and INSTR.

This means that there will need to be multiple Table entries, like for the existing Sub_Code and Neq_Code for the minus operator. For example with MID$, there will be Mid2_Code and Mid3_Code. Initially the Parser will set the code to Mid2_Code since that will be the first entry found in the table.

When the MID$ token is about to be added to the output list, the Translator will have the number of operands that needs to be checked. If the number matches what's in the table, nothing further needs to be done. If the number doesn't match, the Translator either needs to return an error or go looking for another Table entry with the correct number of operands found. Therefore, there needs to be a flag in the Table that indicates that there are more entries. If this flag is set then the Translator needs to look for it.