[antlr-interest] Grammar Perplexity in v3.0 (More)

[Randall R Schulz]

Terence,

On Sunday 12 November 2006 08:46, Terence Parr wrote:
> On Nov 12, 2006, at 8:44 AM, Randall R Schulz wrote:
> > plainTerm
> >
> >     :    AtomicWord ( '(' arguments ')' ) ?
> >
> > AtomicWord
> >
> >     :   LowerWord
> >
> >     ;
>
> These rules are a problem.  AtomicWord is unreachable as both rules
> can match it's input.  You will never see it in the parser.

I'm afraid I don't get it. Which "both" are you referring to? Atomic 
word is a basic symbol token. It's used in several grammar productions, 
including, of course, plainTerm. How does one structure their grammars 
to capture this sharing? How do you stratify a mixed grammar into 
non-overlapping lexical and syntactic portions?

Looking at the sample Java grammar (examples-v3/java/java.g), I seem to 
see exactly these kinds of rules in the same relationship.


> Ter


Randall Schulz