Michael Glaesemann wrote:
> However, as you point out, Postgres doesn't appear to take this into
> account:
>
> postgres=# select regexp_replace('oooZQoooAoooQooQooQooo', $r$(Z(Q)
> [^Q]*A.*(\2))$r$, $s$X$s$);
> regexp_replace
> ----------------
> oooXooo
> (1 row)
>
> postgres=# select regexp_replace('oooZQoooAoooQooQooQooo', $r$(Z(Q)
> [^Q]*A.*?(\2))$r$, $s$X$s$);
> regexp_replace
> ----------------
> oooXooo
> (1 row)
I think the reason for this is that the first * is greedy and thus the
entire expression is considered greedy. The fact that you've made the
second * non-greedy does not ungreedify the RE ... Note the docs say:
The above rules associate greediness attributes not only withindividual quantified atoms, but with branches and entire
REsthatcontain quantified atoms. What that means is that thematching is done in such a way that the branch, or whole
RE,matchesthe longest or shortest possible substring as a whole.
It's late here so I'm not sure if this is what you're looking for:
alvherre=# select regexp_replace('oooZQoooAoooQooQooQooo', $r$(Z(Q)[^Q]*?A.*(\2))$r$, $s$X$s$);regexp_replace
----------------oooXooQooQooo
(1 fila)
(Obviously the non-greediness has moved somewhere else) :-(
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
