On 22/09/2010 16:03, Mark Proctor wrote:
On 22/09/2010 14:40, Wolfgang Laun wrote:
Service:
http://www-cgi.uni-regensburg.de/~brf09510/syntax.html
<http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.html>
The grammar syntax is the same as used in DRL.g but stripped of all
the antsy additions, and simplified.
@Mark: I'm well aware of the limitations of a 1:1 translation of a
parser's grammar into diagrams. I have reduced the splits into
separate rules in DRL.g considerably. But what do you want to hide
from the users? The syntax is the syntax, and there's no
sweet-talking around it after you have reduced all the noise from
technical splits.
One thing that might help would be deprecating things like infix or/and.
yes agreed. Simplifying the grammar, reducing ambigiiouty or multiple
ways of doing the same thing, will make any resulting grammar both
easier ot maintain and grok.
Edson, Davide and I have already discuss this. Both are working on a
new parser and are trying to address these issues. So things that are
doing are:
Single binding on 'or'
$binding : ( Pattern() || Pattern() )
We are thinking of only allowing 'or' between patterns and not
allowing users to mix and match 'or' and '||'. Inside of patterns
'||' is the only connective allowed and will remain so.
We will also probably make a choice and only allow infix 'or' and
'and', at the moment users can chose infix or prefix. Personally I
find prefix quite attractive as it works sort of like a "choice":
(or Person( ... )
Person( ... )
Person( ...) )
But I think most peopel are more comfortable with infix:
(Person( ... ) or
Person( ... ) or
Person( ...) )
return value, eval, literal constraint, variable constraint are going.
These are left overs of a Clips based grammar. So instead we'll have a
generic "expr" class that follow more common modern ASTs for
expression engines, like say MVEL.
Davide has also requested that we make $ prefix mandatory for LHS
bindings as that is deterministic and again makes the grammar cleaner.
I personally like it being optional and it's still open to debate. But
I recognise the need to have better maintained grammar, that is more
consistent and regular with easy to main documentation.
Mark
I would add that these would be backward compatability breaking changes,
we've been backwards compatible now for almost 5 years.... However it
shouldn't be too hard to have a 5.x parser spit out 6.x compatible DRL.
Mark
Some rules can be omitted if they coincide with Java's own rules;
just add an explanation.
-W
On 22 September 2010 14:56, Anstis, Michael (M.) <[email protected]
<mailto:[email protected]>> wrote:
What was the service and was it the ANTLR grammar you uploaded to
generate the images?
Thanks,
Mike
-----Original Message-----
From: [email protected]
<mailto:[email protected]>
[mailto:[email protected]
<mailto:[email protected]>] On Behalf Of Wolfgang
Laun
Sent: 22 September 2010 13:38
To: Rules Dev List
Subject: [rules-dev] Drools syntax diagrams - redrawn
I've found this online service and stuffed the Drools grammar
into it.
You may see the results while they are still there:
http://www-cgi.uni-regensburg.de/~brf09510/syntax.tmp/x45371x0x0x.ebnf.h
tml
<http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebnf.h%0Atml>
<http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebn
f.html
<http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebn%0Af.html>>
-W
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