[antlr-interest] summary of trip to Montreal/SableCC land

[Terence Parr]

Howdy,

Just met with Etienne Gagnon, the SableCC guy, in Montreal and gave an 
ANTLR lecture.  Etienne is a smart guy and seems to have the same goal 
as I do in general: building good parsing / translation tools for 
commercial programmers.  His further goals are language independence 
and hiding the complexities of LR-based parsing from the grammar 
developer.  I believe SableCC is currently LALR(1), but he has finished 
creating a method that will get him closer to LR(1).  He has the start 
of a visual debugger (for eclipse) that seems nice.  For language 
independence, SableCC does not allow actions in the grammar.  As for 
tree construction, he builds trees that are "type safe"; that is, they 
conform to a particular structure specified in a "tree grammar" 
section.  ANTLR takes the opposite approach which is: you have to parse 
trees multiple times during translation so let the tree walker check 
the structure ("type safety" in his terminology) as it must traverse it 
anyway.  Further, the structure changes so the original tree grammar 
("type structure") is no longer valid after creation.

He is going to try to implement linear approximate lookahead for 
SableCC.  I showed him some tricks :)

He loved the dynamically-scoped attributes thing, by the way. :)

Terence
--
CS Professor & Grad Director, University of San Francisco
Creator, ANTLR Parser Generator, http://www.antlr.org
Cofounder, http://www.jguru.com
Cofounder, http://www.knowspam.net enjoy email again!





 
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