Hello everybody,
I'm trying to write a parser for sql92 and I have some trouble with the
tables in the from-clause, especially with the joins within it. I'd like
to solve the ambiguities caused by the recursion in this case. I read
the "Definitive ANTLR Reference" and now i'm wondering if my problem is
something like the "if-then-else ambiguity" mentioned in chapter 11
(p.275) and I can just ignore the warning.
If not, how can I solve the ambiguity? I'm happy about any clue.
The grammar (the mentioned part) is attached for better understanding :)
Thanks in advance,
Matthias
--
Matthias Kiehl
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-~----------~----~----~----~------~----~------~--~---
grammar test;
test : table_ref;
table_ref
: table_ref_simple ((CROSS_JOIN table_ref) | qualified_join)*
;
table_ref_simple
: (qualified_name | LPAREN (table_ref | select_stmt) RPAREN) (AS?
ID (LPAREN column_name_list RPAREN)?)?
;
qualified_join
: NATURAL JOIN table_ref
| (INNER | (LEFT | RIGHT | FULL) OUTER?)? JOIN table_ref join_spec
;
join_spec
: ON search_condition
| USING LPAREN column_name_list RPAREN
;
column_name_list
: ID (',' ID)*
;
qualified_name
: ID ('.' ID)*
;
search_condition
: ;
select_stmt
: ;
LPAREN : '(';
RPAREN : ')';
AS : 'as';
NATURAL : 'natural';
INNER : 'inner';
LEFT : 'left';
RIGHT : 'right';
FULL : 'full';
OUTER : 'outer';
UNION : 'union';
JOIN : 'join';
ON : 'on';
USING : 'using';
CROSS_JOIN
: 'cross' ' '+ 'join'
;
ID
: (SINGLE_LATIN_LETTER | INT) (SINGLE_LATIN_LETTER | INT | '_')*
;
fragment
SINGLE_LATIN_LETTER
: 'a'..'z'
| 'A'..'Z'
;
fragment
INT : '0'..'9';
WS : (' ' | '\t' | '\n' | '\r')+ {$channel = HIDDEN;} ;
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