[antlr-interest] ISO SQL 2003 Grammar

[Douglas Godfrey]

I generated a C parser and lexer. they both generate and compile
successfully
on my machine with 8GB heap allocated to Antlr. Any less and both Antlr
and 
Antlrworks encounter numerous bugs due to unchecked memory allocation
failures.

Antlrworks needs 512MB to 1GB just to be able to edit the grammar. Antlr
needs 
a minimum of 6GB to generate code for just a few rules with exponential
lookahead. In my emails to the antlr-interest group I discuss how to
refactor 
the grammar to reduce it's memory requirement.

I havent had time to work on the SQL2003 grammar due to my day job writing
the join engine to a database system.

If you have the time to work on the SQL2003 grammar start unravelling the
recursive dependancies at rule nonparenthesized_value_expression_primary.
There is a set of about 30-40 rules with multiple recursion pathways such
that any rule in the set can be reached from any other rule in the set.
That is why the memory requirement is so large.

I don't believe that it will ever be possible to get a working parser in
Java. A C language parser on the other hand is quite possible.

On 10/9/11 11:51 PM, "Ivan Bludov" <ivan.bludov at gmail.com> wrote:

>So as I wrote I read your previous posts ( and file comments of
>cause). So at first I was surprised enough that so much system
>resources was needed. But as Terence wrote "With 3.3 I find that it
>terminates in 12s on my box with 220M ram"
>(http://www.antlr.org/pipermail/antlr-interest/2011-April/041439.html).
>So I got the same result with antl 3.3. So build results depend on
>antlr version (different results on different antlr version). So with
>antl 3.4 the building process seems to fall into infinite loop and
>thus system resources don't matter. So with 3.3 build result is
>successful about few seconds, but the generated parser has some
>errors. The critical problem - I think - is that the parser has
>duplicated (identical) case in some switch statements. So I posted
>these thoughts.
>
>Douglas Godfrey, I appreciate your work on SQL2003 parser. But I
>couldn't see the work result. Could you write your environment? Antlr
>version? Have you already use your generated parser in some another
>project? Because the generated parser has some another errors: "big
>grammar" problem with 64kbyte class - but it is another problem.
>
>Ivan Bludov