Table – Entry Virtual Functions

The implemented commands (LET, REM, PRINT, INPUT, and INPUT PROMPT) each have different initialization values (a code for LET and REM, an option name for the INPUTs, a translate function pointer for all except REM, a recreate function pointer for all but LET, and an encode, operand text and remove functions pointers for only REM).  Creating a single command sub-class constructor to cover these would be messy, and so would creating a different constructor each.

The intention was to replace the functions pointers with virtual pointers, so it was not worth the effort to try and handle these.  Virtual functions were added to the base table class, which temporarily call the function pointer if set (translate and recreate), or just call the function pointer (encode, operand text, and remove).  For the command sub-class, which is only used for commands not yet implemented, the translate virtual function overrides the base class function and throws a "Not Yet Implemented" error.

The is code with operand access function checked if the operand text function pointer was set.  Since the function pointers will be removed, another method for checking if the code has an operand was needed.  A new Operand table flag was added to the REM, REM operator, three constant, and six variable table entries.  This access function was modified to check this flag.

The users of the function pointers (translator and program model) were modified to call the virtual functions.  For the encode, operand text, and remove functions, the program model needs to call the is code with operand function before calling the function.  This resulting code a bit messy and needs to be improved.

[branch table commit c24cf75c90]