[antlr-interest] minor 3.0b4 bug?
John B. Brodie
jbb at acm.org
Sat Oct 7 06:35:14 PDT 2006
>service : LParen paramList* RParen ;
>I get the following error :
>ANTLR Parser Generator Early Access Version 3.0b4 (??, 2006) 1989-2006
>D:\ActiveProjects\IdeaProjects\Jtest1\src\SGenParser.g:86:12: Decision can
>match input such as "RParen" using multiple alternatives: 1, 2
>As a result, alternative(s) 2 were disabled for that input
>D:\ActiveProjects\IdeaProjects\Jtest1\src\SGenParser.g:86:12: The following
>alternatives are unreachable: 2
>Where is Alt 2?
think of the above two rules as this equivalent
service : LParen aUniqueRuleName RParen ;
aUniqueRuleName : /*empty*/ | paramList aUniqueRuleName ;
paramList : /*empty*/ ;
the rule introduced by the transformation has two alternatives which, in this
case, are both empty. leading to the reported ambiguity problems.
Hope this helps...
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