[antlr-interest] Binary support

[The Researcher]

Hi Andi,

I have actually tried to modify ANTLR to read binary files and I eventually
set it aside and went in a different direction. I did so knowing that it
might not be right but to also understand WHY it might not be right. One of
the first things you will learn on this endeavor is that K=0 because you
know the layout of the binary data. If you are trying to write a parser to
parse unknown binary formats, as Ron mentioned, then K>0 and since not all
of the patterns are known, success may not be achieved. This is where PROLOG
comes in handy.

Another aspect of binary files is that they tend to be context sensitive and
AFAIK ANTLR was not designed to handle Type 1 grammars. See
http://en.wikipedia.org/wiki/Chomsky_hierarchy

You also have to deal with unions and tagged unions. See
http://en.wikipedia.org/wiki/Union_(computer_science)
http://en.wikipedia.org/wiki/Tagged_union

How would ANTLR retain the tags, or should the grammar designer be
responsible for maintaining them like a symbol table.

While I will point this out because you should be aware of it, I am not
recommending it. I haven't worked with ANTLR v4 yet, but you can give it a
test by getting it from https://github.com/antlr/antlr4

>From a practical stand point, if ANTLR were modified for this, how much
change would it cause for those not parsing binary files. I don't suspect
that the other target grammars would use it, so only the Java target would
have it. And since Java is not bit friendly, you change one problem for
another.

Eric