[antlr-interest] Creating a main() for C++ code, passing params on command line

[Bryan Ewbank]

Paul D Watson wrote:
>
> It is clearly evident that I am new to antlr.  I have searched quite a bit
> through the ANTLR Reference Manual and with Google to find out about how a
> main() is created for antlr generated programs.  There are main.cpp and
> Main*.cpp files around in the examples directory.  But I am hoping to find
> some reference documentation that will tell what must, or must not, go into a
> main() for antlr generated programs.

Welcome to ANTLR :)

For C++, the main thing you need is to define the necessary factory; the
reference manual, in the section on C++ code, should describe it.  Without this
step, your program will crash the first time it tries to create an AST node.

There are several ways to pass information to the ANTLR-generated class
objects; think of it as a normal C++ class, and you should see what I mean.

	- class-global (i.e., static) items, to control the behavior of all
	  instances created.
	- as constructor argument, to bind a specific instance of the class
	  with specific information.  for example, you must pass a lexer to the
	  default constructor for a parser.  this requires the most "hacking"
	  because you need must suppress the normal constructors if they do not
	  make sense.  the end of the reference manual talks about
	  noDefaultConstructor, I think.
	- as arguments to specific productions or member functions that are
	  defined in the header of the class definition.

Hope this helps; no specific information, but general ideas.  Take a look at
the (default) generated code for C++, and you should see that the interface
(the generated *.hpp) is actually not that unusual.

- Bryan Ewbank