1) The document discusses common challenges faced when developing grammars for Drools and Hibernate, two important Java projects that use domain-specific languages. 2) It addresses how to handle soft keywords, internationalize error messages, implement semantic predicates, and add syntax highlighting and autocomplete to editors for grammars generated by ANTLR. 3) The presentation seeks input from attendees on how to adapt grammars to existing structures, split parse trees, and avoid tight coupling between lexers, parsers and tree walkers.

1. ANTLR
Challenges in grammar development:
Drools & Hibernate real cases
Alexandre Porcelli
Caravela

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must admit: i’m a BIT nervous

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Alexandre Porcelli Chief Technology Officer
porcelli@caravelatech.com
Alexandre Porcelli
Creator &
Project Lead
Alexandre Porcelli
Commiter
Alexandre Porcelli
Commiter / Parser Maintainer
Alexandre Porcelli
Commiter / Parser Developer

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why i'm excited to be here?

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to be one more nerd in the audience?
NO

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to take the antl[e]r photo?
Definitely
NOT!

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to drink some beers with you?
NO....
-- that's not entirely true ;) --

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to learn...
from you!

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interactive talk....

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jboss.org/drools
one of the most important product on JBoss
SOA Platform
dsl language: DRL

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hibernate.org
one of the most used java library...
dsl languages: HQL, EJB-QL & Criteria Query*

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common habits
antlr version 3.1.x
tree walkers
lots of virtual tokens
never_change: (generated files | antlr templates) ;
gUnit
proprietary token class

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common challenges

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keywords as variables: soft keywords
“ ”
Terence Parr, 2007

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how to

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error messages: internationalization

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how to

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semantic predicate
Person( ( age > 60 && age < 70 ) || ( age > 50 && age < 55 ) )
restr_connective
Person( ( age ( > 60 && < 70 ) || ( > 50 && < 55 ) )
constraint

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how to

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editor: syntax highlighting

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how to

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editor: autocomplete

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how to
i’ll not show my terrible solution
* if you whant see that -> get drools code and check it ;)

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chalange: try to adapt to an existing structure
what we’d love to have:
- implement interface @ parsers & walkers
- token types declared outside generated
code (why not an interface?) -> avoid
code coupling with lexers, parsers or
treewalkers

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split the tree

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how to

32. ANTLR Thank You
porcelli@caravelatech.com
caravelatech.com
www.linkedin.com/in/alexandreporcelli
twitter.com/porcelli
no time for that... yet!