[antlr-interest] Deciphering the TreeWalker error message ...

[srinivasan karthikeyan pitchai]

Hi Folks,
I forgot to mention.  The compoundExpression rule has options{backtrack 
= true;}  set that is it reads like

compoundExpression
options {backtrack = true;}
:
      ^(sclarSubExpression  conversion_clause)
     | sclarSubExpression
;

Thanks,
Vasan



On 7/21/2011 10:56 AM, srinivasan karthikeyan pitchai wrote:
> Jim, Gray, Loring,
> Thanks for pitching in to give me some direction to focus on.
>
> ANTLR Gurus,
>
> I've solved the issue.  Still I am unable to reason out my fix.
>
> I am providing the offending grammar snippet below and would appreciate
> your rationale to get an insight into the problem and how the fix works!!
>
> The below rule fails with the "
>
> no viable alt; token=[@-1,0:0='DOWN'" error message
>
> compoundExpression:
>       ^(sclarSubExpression  conversion_clause)
>      | sclarSubExpression
> ;
>
> However when I change the rule like the following, i.e make the
> conversion_clause optional  and then remove the second alternative every
> thing works fine!!  In my mind both the rules are semantically identical.
>
> compoundExpression:
>       ^(sclarSubExpression  conversion_clause?)
> ;
>
> Thanks a ton.
>
> -Vasan
>
> On 7/21/2011 4:16 AM, Jim Idle wrote:
>> Or use the dot description producing methods and create a nice graphic
>> with graphviz. Much easier to see that way.
>>
>> Jim
>>
>>> -----Original Message-----
>>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>>> bounces at antlr.org] On Behalf Of Gary Miller
>>> Sent: Wednesday, July 20, 2011 3:44 PM
>>> To: antlr-interest at antlr.org
>>> Subject: Re: [antlr-interest] Deciphering the TreeWalker error message
>>> ...
>>>
>>> I often find it usefully to print out the AST (toStringTree in Java)
>>> and walk through the tree grammar manually.
>>>
>>> Regards
>>> Gary
>>>
>>> On Thu, Jul 21, 2011 at 3:15 AM, Loring Craymer<lgcraymer at yahoo.com>
>>> wrote:
>>>
>>>> "UP" and "DOWN" tokens (start/end of child list for tree) do not have
>>>> location information attached so no line/column error reporting.
>>>> Mostly the error says that you started a subtree that your grammar
>>>> does not match, probably an LPAREN or RPAREN rooted subtree from your
>>>> report of cases where you do or do not get the error.
>>>>
>>>> --Loring
>>>>
>>>>
>>>>
>>>>> ________________________________
>>>>> From: srinivasan karthikeyan pitchai<
>>>> srinivasan.karthikeyan.pitchai at oracle.com>
>>>>> To: antlr-interest at antlr.org
>>>>> Cc: Terence Parr<parrt at cs.usfca.edu>
>>>>> Sent: Wednesday, July 20, 2011 9:46 AM
>>>>> Subject: [antlr-interest] Deciphering  the TreeWalker error message
>>> ...
>>>>> Hi Folks,
>>>>> What does the ANTLR walker error message like the following mean?
>>>>>
>>>>> no viable alt; token=[@-1,0:0='DOWN'
>>>>>
>>>>>
>>>>> Would appreciate any general guidance/suggestions to zero in on the
>>>>> errors of this nature.
>>>>>
>>>>> Thanks,
>>>>> Vasan
>>>>>
>>>>>
>>>>> Input sql:
>>>>> -----------
>>>>>
>>>>> select (1) from table1
>>>>> where 2 between 3 and 4;
>>>>>
>>>>>
>>>>> Error Message:
>>>>> --------------------
>>>>>
>>>>> TDWalker1.g: node from after line 2:8 [start1, startStatement, dml,
>>>>> query_term, query_expression, query, query_unit, where_clause,
>>>>> condition_list, condition_subexpression, condition] Walker1: no
>>>>> viable alt; token=[@-1,0:0='DOWN',<2>,0:-1] (decision=127 state 0)
>>>>> decision=<<590:1: condition options {backtrack=true; } : ( ^(
>>>>> comparison_operator ( condition_quantifier )? c1= condition c2=
>>>>> condition ) | ^( BETWEEN expression ^( and_or_operator c1= condition
>>>>> c2= condition ) ) | ^( condition_operator expression c1= condition
>>> ^(
>>>>> ESCAPE escape_character ) ) | ^( condition_operator expression c1=
>>>>> condition )
>>>>> | ^( condition_operator expression_list c1= condition ) | ^( NOT c1=
>>>>> condition ) | ^( EXISTS expression ) | ^( IS_NOT_NULL expression ) |
>>>>> ^( IS_NULL expression ) | ^( IS_NOT expression UNTIL_CHANGED ) | ^(
>>>>> IS expression UNTIL_CHANGED ) | ^( IS_NOT expression UNTIL_CLOSED )
>>> |
>>>>> ^( IS expression UNTIL_CLOSED ) | expression | condition_list );>>
>>>> context=......
>>>>> However the following SQL, that just doesn't have the parenthesis
>>>>> around 1,  works fine!!!
>>>>>
>>>>> select (1) from table1
>>>>> where 2 between 3 and 4;
>>>>>
>>>>>
>>>>> List: http://www.antlr.org/mailman/listinfo/antlr-interest
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