From: Tom Lane <tgl@sss.pgh.pa.us>
To: srn@coolheads.com
Cc: pgsql-docs@postgresql.org
Subject: Re: can't be both non-capturing and still capture
Date: Mon, 03 Jul 2017 22:10:03 -0400
Message-ID: <25895.1499134203@sss.pgh.pa.us> (raw)
In-Reply-To: <20170703204755.27952.9007@wrigleys.postgresql.org>
References: <20170703204755.27952.9007@wrigleys.postgresql.org>
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srn@coolheads.com writes:
> Here, the whole regexp is non-capturing, right, so how can the result be
> reported as shown?
No, the outer parens are non-capturing, but the ones inside them still
are capturing parens.
Perhaps it would clarify matters if you tried it with plain outer parens:
=# SELECT regexp_matches('abc01234xyz', '((.*?)(\d+)(.*)){1,1}');
regexp_matches
-----------------------------
{abc01234xyz,abc,01234,xyz}
(1 row)
In this case we get a report from each of the four sets of capturing
parens. Or another example:
=# SELECT regexp_matches('abc01234xyz', '((?:.*?)(\d+)(.*)){1,1}');
regexp_matches
-------------------------
{abc01234xyz,01234,xyz}
(1 row)
Outer parens capture, first inner set don't, other two inner sets do.
regards, tom lane
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To: pgsql-docs@postgresql.org
Cc: tgl@sss.pgh.pa.us, srn@coolheads.com
Subject: Re: can't be both non-capturing and still capture
In-Reply-To: <25895.1499134203@sss.pgh.pa.us>
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