[antlr-interest] SQL grammar, help on ambig warns

[Ruslan Zasukhin]

Hi Guys,

At last of end we have found time to work on our own SQL 92 grammar.
We can compile grammar without errors.
Problem only with some ambig warns.

For example, I get warn

> E:\antlr272a2\OBL\OBL_SQLGrammar.g:342:23: warning: nondeterminism upon
> E:\antlr272a2\OBL\OBL_SQLGrammar.g:342:23:     k==1:LPAREN
> E:\antlr272a2\OBL\OBL_SQLGrammar.g:342:23:     between alts 1 and 2 of block

on this rule:  (By the way, k = 1 for parser, for k = 2 the same problem)

--------------------------------------------------------------
character_string_type
    :    ( "character" | "char" )
            (    "varying" LPAREN! unsigned_integer RPAREN!
            |     ( LPAREN! unsigned_integer RPAREN! )?     <<<<<< here
            )
    |    ("varchar" | "string")
            (     LPAREN! unsigned_integer
                     (COMMA! character_string_literal)? RPAREN! )
    ;    
--------------------------------------------------------------

Is this rule incorrect ???

If remove ?  Then it compiles fine.

Also when I look into generated C++ Parser, for code of problematic line
I see that ANTLR test on tokens from MANY MANY other rules (that probably
call this one). 

I can understand why this is needed, just was surprised.
I did think that each rule is self-contained, but it seems generated code
depend on where and how a rule is called also.


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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