>>If "searchstring" is to the right and left of an @ sign, it should
match.
After having some time while driving a car today - my 2 cents for using a
named capture group and backreference ?<match_1> \k<match_1> - instead
of numbered (...) \1
(?<match_1>searchstring)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>
When ever possible don not use .* - instead look for a less greedy
variant. .* with the (?is: switch (assp uses it) will force the regex
engine to search until the end of the string (mail) and to trace back
(several thousand times).
There are better (less CPU, less time) solutions for the regex using
lookahead assertations - but this will go beyond the scope.
There is no need to disable regex-optimization anyway - because there is a
\r in the regex. The optimizer has a bug, which destroys the \r to \\r -
so assp disables the optimizer if a regex contains a \r .
How ever, to prevent the regex from failing after possible future assp
code changes, you may use:
<<<(?:(?<match_1>searchstring)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>)>>>
or
(?<match_1>searchstring)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>.?
the later one seems to be the best of both
normaly you would write
<<<(?<match_1>searchstring)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>>>>
but assp will destroy the trailing four >>>> (I'm sure)
If more than one string is searched - use:
~<<<(?:(?<match_1>searchstring1|searchstring2|searchstring3)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>)>>>~
or
~<<<(?<match_1>searchstring1|searchstring2|searchstring3)[^@\r\n]{0,64}\@[^@\r\n]{0,64}\k<match_1>.?>>>~
Want to know more about regular expressions? ->
http://www.rexegg.com/regex-lookarounds.html
Thomas
Von: "K Post" <nntp.p...@gmail.com>
An: "ASSP development mailing list" <assp-test@lists.sourceforge.net>
Datum: 04.11.2021 02:29
Betreff: [Assp-test] RegEx Backreferences - the basics
I've got nothing in my TestRe file except for a single line:
~<<<(?:^|\n\r).*(searchstring).*@.*\1.*>>>~
The idea is to log any time there's a line that includes "searchstring" on
the right and left of an @. This is just a very rudimentary test because
backreferences seem to error for me. I would expect this to match
searchstring@searchstring
something else seachstring more @ whatever searchstring bla
If "searchstring" is to the right and left of an @ sign, it should match.
Regex101.com seems to confirm that this works. Like I said, super basic.
However, if I enter ~<<<(?:^|\n\r).*(searchstring).*@.*\1.*>>>~ as the
only line in TestRe file, I get a warning in the log:
- Reference to nonexistent group in regex; marked by <-- HERE in
m/(?is:(?:^|\n\r).*(?:searchstring).*@.*\1 <-- HERE .*)/
- try using unoptimized regex
To my understanding, the <<< >>> surround should turn of regex
optimization for that line, which enables backreferencing (\1) to work and
the ~ is required because there's an or in there. Shouldn't the \1
reference (searchstring) ? I don't understand why assp thinks that \1 is
a reference to a non-existent group.
I also tried removing the <<< >>> and adding assp-do-not-optimize to the
top of the TestRe file. No difference. No matter how simple I make the
regex, even (.*)@\1, it still complains about the invalid backreference.
I've got to be missing something incredibly obvious. I've read through
the regex doc in docs, but that doesn't talk about backreferencing in ASSP
and I can't find anything in the GUI that makes mention. I've seen posts
here indicating that backreferencing matches is possible with an
unoptimized expression.
A shove in the right direction would be greatly appreciated.
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