Fix parsing of ignored operators in websearch_to_tsquery().

The manual says clearly that punctuation in the input of
websearch_to_tsquery() is ignored, except for the special cases
of dashes and quotes.  However, this failed for cases like
"(foo bar) or something", or in general an ISOPERATOR character
in front of the "or".  We'd switch back to WAITOPERAND state,
then ignore the operator character while remaining in that state,
and then reach the "or" in WAITOPERAND state which (intentionally)
makes us treat it as data.

The fix is simple enough: if we see an ISOPERATOR character while in
WAITOPERATOR state, we have to skip it while staying in that state.
(We don't need to worry about other punctuation characters: those will
be consumed as though they were words, but then rejected by lexizing.)

In v14 and up (since commit eb086056f) we can simplify the code a bit
more too, because there is no longer a reason for the WAITOPERAND
state to distinguish between quoted and unquoted operands.

Per bug #18479 from Manos Emmanouilidis.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/18479-d9b46e2fc242c33e@postgresql.org

src/backend/utils/adt/tsquery.c

@@ -433,7 +433,7 @@ gettoken_query_websearch(TSQueryParserState state, int8 *operator,
 				}
 				else if (ISOPERATOR(state->buf))
 				{
-					/* or else gettoken_tsvector() will raise an error */
+					/* ignore, else gettoken_tsvector() will raise an error */
 					state->buf++;
 					state->state = WAITOPERAND;
 					continue;
@@ -492,6 +492,12 @@ gettoken_query_websearch(TSQueryParserState state, int8 *operator,
 					*operator = OP_OR;
 					return PT_OPR;
 				}
+				else if (ISOPERATOR(state->buf))
+				{
+					/* ignore other operators in this state too */
+					state->buf++;
+					continue;
+				}
 				else if (*state->buf == '\0')
 				{
 					return PT_END;

src/test/regress/expected/tsearch.out

@@ -2539,12 +2539,19 @@ select websearch_to_tsquery('simple', 'abc <-> def');
  'abc' & 'def'
 (1 row)
 
+-- parens are ignored, too
 select websearch_to_tsquery('simple', 'abc (pg or class)');
   websearch_to_tsquery  
 ------------------------
  'abc' & 'pg' | 'class'
 (1 row)
 
+select websearch_to_tsquery('simple', '(foo bar) or (ding dong)');
+      websearch_to_tsquery       
+---------------------------------
+ 'foo' & 'bar' | 'ding' & 'dong'
+(1 row)
+
 -- NOT is ignored in quotes
 select websearch_to_tsquery('english', 'My brand new smartphone');
      websearch_to_tsquery      

src/test/regress/sql/tsearch.sql

@@ -727,7 +727,10 @@ select websearch_to_tsquery('simple', ':');
 select websearch_to_tsquery('simple', 'abc & def');
 select websearch_to_tsquery('simple', 'abc | def');
 select websearch_to_tsquery('simple', 'abc <-> def');
+
+-- parens are ignored, too
 select websearch_to_tsquery('simple', 'abc (pg or class)');
+select websearch_to_tsquery('simple', '(foo bar) or (ding dong)');
 
 -- NOT is ignored in quotes
 select websearch_to_tsquery('english', 'My brand new smartphone');