Re: LR(1) Parsing : Error Handling & Recovery

Hans-Peter Diettrich <DrDiettrich1@netscape.net> wrote in
> Unfortunately I couldn't get the article, so here's what I don't understand:
>
>> is:
>>
>> S ::= aSA | \epsilon
>> A ::= aabS | c
>>
>> This grammar (and the language) is LL(2), but there does not exist an
>> equivalent LL(1) grammar.
>
> IMO this grammar is LL(3), not LL(2). There might be a typo in A, which
> might originally read as:
> A ::= abS | c
> resulting in an LL(2) grammar.


Yes, my fault for not carefully checking my post. As written, it's an
LL(3) grammar for a language that is not LL(2). Remove one 'a' from
the 'A' rule to get an LL(2) grammar for a language that is not LL(1).
Add 'a's to get an LL(k) grammar for a language that is not LL(k-1)
for any k...


Chris Dodd
cdodd@acm.org

Return to the comp.compilers page.
Search the comp.compilers archives again.