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;} ;