[antlr-interest] ANTLR 3.0 tree construction proposal
parrt at cs.usfca.edu
Mon Jan 31 13:56:36 PST 2005
On Jan 31, 2005, at 1:41 PM, Martin Probst wrote:
>> What is my point? Tree construction syntax is already a barrier to
>> overcome to reading Antlr grammars.
> It might be too late or just insignificant and certainly somewhat
> offtopic but here is my users perspective: I find the ANTLR style of
> defining tree construction _very_ strange. IMHO it's close to code
> obfuscation with all these ^, !, :, =, # and .
Well, the ^ and ! should be very clear, right? You are merely
specifying what is a subtree root and what is to be ignored. It's the
interaction with #(...) etc... in 2.x that is confusing I think.
> I would really prefer it if ANTLR would stick to some clear keywords
> maybe find a way of distinguishing ANTLR actions (e.g. where you do
> $setType and similar things) and actions in the target language.
I'm trying to avoid having any special stuff in actions. :) The
rewrites help a lot. I don't anticipate needing actions to build trees
at the moment.
> The readability of tree construction syntax is really very poor at the
Thanks for the feedback!
Do you think the new rewrite stuff would be easy to understand? Some of
surely would. For example, build a flat tree with elements reordered:
r : A B => B A ;
Will that help do you think or is it just as bad? I really want to get
What are your thoughts on Loring's counter-proposal?
CS Professor & Grad Director, University of San Francisco
Creator, ANTLR Parser Generator, http://www.antlr.org
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