[antlr-interest] Visually display the DFA ANTLR generates

[Geoffrey Zhu]

For example, for the input "( security" the interpreter works well on
the below grammar, but the ANTLR genereated code chokes on it. I guess
that as long as there are two code bases (ANTLR and WORKS), there are
discrepencies. Maybe Works can employ antlr to do the work. Then there
is no discrepency.

ID : ('a'..'z')+;
fragment WS : ' ' | '\t' ;
LPAREN    : '(' ;
LP_SELECT : '(' WS* 'select';
prog: (ID|LPAREN|LP_SELECT|WS)+ ;
 

-----Original Message-----
From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of Randall R Schulz
Sent: Wednesday, June 27, 2007 9:20 AM
To: antlr-interest at antlr.org
Subject: Re: [antlr-interest] Visually display the DFA ANTLR generates

On Wednesday 27 June 2007 07:09, Geoffrey Zhu wrote:
> I just don't know AntlrWorks's fidelity to the actual code. I already 
> found one case where the ANTLRWorks interpreter works differently from

> the actual generated code. Does it read the generated code to build 
> the graph?

If ANTLRworks has a deficiency, it is its lack of documentation.

As I learned here yesterday, when acting in its "Intepreter" mode,
ANTLRworks ignores syntactic predicates. For grammars that include them,
this makes the interpreter unuseful. And keep in mind that even if you
do not explicitly write any syntactic predicates, if you enable
backtracking ANTLR itself will generate syntactic predicates for you.

In these cases, you must use the ANTLRworks debugger to test your
grammar's behavior. But it is very useful to do so.


And if there's some sort of discrepancy between ANTLRworks and ANTLR, 
it's a bug and either Terence Parr or Jean Bovet will fix it (if you 
report it).


Randall Schulz



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