Parser – Design

The Parser code will be a collection of functions and variables needed by the functions. All this could be coded in its own source file and either the variables are global in the source file (static to keep functions in other files from being able to access them) or put into a structure and passed between the functions. This latter approach is better, at least when writing C code.

However, with C++, the best way will be to implement the whole Parser is as a C++ class. This allows all the functions to share the variables (which is essentially a structure) and keeps them private to the functions. All the functions can also be kept private except for the main function that will be called to parse a line. The class definition will be in the main header file (ibcp.h) and the code will be in the parser.cpp source file. Each component in the Interactive BASIC Compiler will be a class, so it's best not to have a separate include file for each one. The other definitions (like the token structure and the Operator Table) will also be put into ibcp.h. The organization of the definitions will be adjusted as the project grows. The List and String classes can remain in their own files for now.