[antlr-interest] Why and how exactly does ANTLR manage to fail on non recursive grammar for finite language?

[Nikolay Ognyanov]

Well, there is nothing else that the extra SUFFIX can belong to 
according to the
grammar so this is not derivation/parsing of the statement per the grammar.

Regards
Nikolay

Loring Craymer wrote:
> Not true; your example can be interpreted either as
>
> (expr1:  PREFIX_1 (expr2:  PREFIX_2 SUFFIX) SUFFIX )
>
> or as
>
> (expr1:  PREFIX_1 (expr2:  PREFIX_2) SUFFIX) SUFFIX
>
> with the extra SUFFIX belonging to something else
>
> --Loring
>
>
>     *From:* Nikolay Ognyanov <nikolay.ognyanov at travelstoremaker.com>
>     *To:* Jim Idle <jimi at temporal-wave.com>
>     *Cc:* antlr-interest at antlr.org
>     *Sent:* Wednesday, August 12, 2009 3:28:16 PM
>     *Subject:* Re: [antlr-interest] Why and how exactly does ANTLR
>     manage to fail on non recursive grammar for finite language?
>     By definition a grammar is ambiguous if there is more than 1 way
>     to derive at least one statement.
>     This is not the case here. There is only 1 way to derive the
>     offending statement
>
>     PREFIX_1 PREFIX_2 SUFFIX SUFFIX
>
>     And it would take the procedure for expr2 just about 3 tokens
>     lookahead to figure out what is the
>     right thing to do. The question is why ANTLR does not do this?
>
>     Regards
>     Nikolay
>
>
>

-- 

*Nikolay Ognyanov, PhD*
Chief Technology Officer
*TravelStoreMaker.com Inc.* <http://www.travelstoremaker.com/>
Phone: +359 2 933 3832
Fax:     +359 2 983 6475

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