Re: BUG #5793: tsquery error

"" <ms@instytut.com.pl> writes:
> The expression 'a & !(c) | a & b' is interpreted as '( a | !c ) & a & b'.
> select 'a & !(c) | a & b'::tsquery;

> Subsequent "rewrites" of the same expression give inconsistent results:

> select '(a & !(c | d)) | (a & b)'::tsquery; -> 'a & !(c | d) | a & b'
> (correct)
> select 'a & !(c | d) | a & b'::tsquery; -> '(a | !(c | d)) & a & b' (not
> correct)

Hmm.  The immediate problem seems to be fixed by

diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
index db9236a474157a7851e2a80516e865c050543634..ba09b3b2ce7fcc0815edf4a4622663291d6f0b8f 100644
*** a/src/backend/utils/adt/tsquery.c
--- b/src/backend/utils/adt/tsquery.c
*************** makepol(TSQueryParserState state,
*** 371,378 ****
              case PT_OPEN:
                  makepol(state, pushval, opaque);

!                 if (lenstack && (opstack[lenstack - 1] == OP_AND ||
!                                  opstack[lenstack - 1] == OP_NOT))
                  {
                      lenstack--;
                      pushOperator(state, opstack[lenstack]);
--- 371,378 ----
              case PT_OPEN:
                  makepol(state, pushval, opaque);

!                 while (lenstack && (opstack[lenstack - 1] == OP_AND ||
!                                     opstack[lenstack - 1] == OP_NOT))
                  {
                      lenstack--;
                      pushOperator(state, opstack[lenstack]);

but I can't say that I've got much confidence in the rest of that
function.  It's an utter kluge.

            regards, tom lane