The code that we provided for the interpreter has been broken into 4 files. The main program file (bbb.pas or bbb.cpp) contains some global declarations and the main program loop. It also contains the code that reads the BBB program in from a file. The code we give you just stores the lines in the same order they are read in from the file. You will probably want to modify this to handle cases where the lines in the input file are out of order.
The scanner is implemented in another file (scan.pas or scan.cpp). Its operation should be fairly straightforward. There are a couple of initialization procedures, and a function to get the next token.
The symbol table (symtab.pas or symtab.cpp) just has a couple of arrays to hold the different types of variables, and a few functions used to set or get the values of the variables.
The parser (parser.pas or parser.cpp) is where you will do most of your work. It contains the implementation of a recursive descent parser for part of the syntax of the language as discussed in section 2.2.2. You will need to complete this implementation.
The C++ version also has a header file (bbb.h which contains some declarations used by all of the other files.
There are several example BBB programs. You should read them to become familiar with the BBB language.