[rules-dev] Drools syntax diagrams - redrawn

[Wolfgang Laun]

See my remarks inline.

On 22 September 2010 17:03, Mark Proctor <mproctor at codehaus.org> wrote:

>  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.
>

OK, a clear distinction avoids confusion.


>
> 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( ...) )
>
> (name ... ) is neither function style nor infix, so removing yet another
way of writing expressions is OK. Let's infix.



> 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.
>
 OK!


>
> Davide has also requested that we make $ prefix mandatory for LHS bindings
> as that is deterministic and again makes the grammar cleaner.
>
I don't understand why it should be "cleaner". After all, a '$' could even
result from a Java identifier although this is discouraged, according to the
Language Spec.

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.
>
> There's one thing that would help: Make the NT identifiers in the grammar
"user friendly". I had to replace all of them with NT identifiers that are
self-explanatory. Also, whenever possible, stick to the terms in the Java
grammar if it's the same thing, e.g. "QualifiedIdentifier", "Block",
"Expression", etc.

-W


> 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.) <manstis1 at ford.com>wrote:
>
>> What was the service and was it the ANTLR grammar you uploaded to
>> generate the images?
>>
>> Thanks,
>>
>> Mike
>>
>> -----Original Message-----
>> From: rules-dev-bounces at lists.jboss.org
>> [mailto:rules-dev-bounces at lists.jboss.org] 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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>
>
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