Le 31/01/2016 18:51, Nicolas Anquetil a écrit :
On 31/01/2016 17:44, Thierry Goubier wrote:
> Le 31/01/2016 15:21, stepharo a écrit :
>> The main problem is that there is no PS/SQL BNF available.
>> I found a SQL92 but nothing else.
>> I found a lexer in antlr but nothing else.
> Just searching five minutes I found many resources and a lot of
> questions about LALR parsing of SQL (3 EBNF for recent SQLs, etc...).
> But the point wasn't that; what a LALR/LR parser gives you is a
> grammar ambiguity and conflicts... PetitParser will happily take your
> grammar ans you will only discover when parsing something that it
> doesn't do what you would like.
> (The reference citation of Aho and Ullman is ... it may be difficult
> to determine what the language is).
> So since you have a grammar, use LALR to check it.
> (I'm sure that LALR parsing of SQL is a solved problem. Maybe the info
> is a bit hard to get, but this is all).
I would love to use Smacc, but I don't feel like restarting from scratch
we want to parse also postgres functions and since this is not part
standard SQL the LALR grammar will not help with that part :-(
But given that you have the LALR postgres grammar in the source code of
For info, I made progress on the grammar, by refactoring part of it
delegating some parsing to "extension parsers" (see
PetitParserExtension-Core by Guilaume)
So I still don't know what happened, but at least I removed the problem :-)
Which is good news :)
>> Le 31/1/16 12:01, Thierry Goubier a écrit :
>>> Le 31/01/2016 11:44, Nicolas Anquetil a écrit :
>>>> On 31/01/2016 07:07, Tudor Girba wrote:
>>>>> Would it be possible to provide an isolated case so that we can
>>>> the isolated test case is in the mail
>>>> for the grammar, I am afraid this will be difficult.
>>>> It is not my grammar but the postgres sql one that Anne and Olivier
>>>> It is their first grammar and despite their best efforts, it shows
>>>> (without blaming anyone, we all know how difficult it can be to
>>>> create a
>>>> full-fledged grammar, and frankly full postgres is proving far more
>>>> complex that I would have ever thought)
>>> Most languages have quirks in the grammar which makes it difficult.
>>> Unexpectedly, LR/LALR type approaches may help because they point out
>>> inconsistencies at the grammar compilation stage.
>>>> I am trying to rationalise and simplify their grammar to understand
>>>> these problems
>>> Probably the right approach.
>>> A simple test I'd do is take parts of it and have a look to the
>>> conflicts raised in SmaCC... The grammar syntax is so similar between
>>> both that you can switch between the two technologies, and, anyway,
>>> given it is a full-fledged grammar, in won't be any longuer in any of
>>> the parser tech available.
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