regex match only outside the double quotes

hifirock has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, i want to remove the certain log lines if its starts with -- or remove the words after the --, but if it is present within the double quotes(" test -- done")then no need of substitution.
for Example :
line1: -- test the line,8,description; (Need to remove the line)
line2:test the line,8,description="testing -- done"; (No need)
line3: test the line,8,description="testing -- done"; -- commented line (need to remove the words after the -- symbol)
if i remove with s/(?<!\").*--.*(?<!\")//g its not working,ca n anyone help me?

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Re: regex match only outside the double quotes by moritz (Cardinal) on Aug 21, 2009 at 07:57 UTC
First extract the quoted groups (with something like Text::CSV or Text::Balanced or even a regex), then look in the remainder for a `--`. That's going to be much easier than finding a "one size fits all" regex. Perl 6 projects - links to (nearly) everything that is Perl 6.	[reply] [d/l]
Re: regex match only outside the double quotes by JavaFan (Canon) on Aug 21, 2009 at 08:51 UTC
You have three cases: Line start with --, you want to remove the entire line aka replace with nothing. A substring starting and ending with " should be left alone, aka replace with itself. -- elsewhere should have the part after the -- removed, aka, replace the entire thing with --. This is trivial in a regexp: `s/("[^"]")\|^--.\n\|(--).*/$1\|\|$2\|\|""/egm;` [download]	[reply] [d/l]
Re^2: regex match only outside the double quotes by SuicideJunkie (Vicar) on Aug 21, 2009 at 13:24 UTC
As long as you don't have escaped quotes... Something like `"App1 said \"Died -- boom!\" at 3:14am"` Would go badly. -SJ How to make perldoc.perl.org resizable too!	[reply] [d/l]
Re^3: regex match only outside the double quotes by JavaFan (Canon) on Aug 21, 2009 at 13:27 UTC
The OP never said anything about escaped quotes, which I why I didn't include them I can extend the regexp to include escapes in my sleep, which both hands tied behind my back. And I'd include loop unrolling.	[reply]
Re^4: regex match only outside the double quotes by SuicideJunkie (Vicar) on Aug 21, 2009 at 18:55 UTC
Re^5: regex match only outside the double quotes by JavaFan (Canon) on Aug 21, 2009 at 22:58 UTC
Re: regex match only outside the double quotes by sanku (Beadle) on Aug 21, 2009 at 09:38 UTC
hi, Try out this one it will work fine. test.txt -- test the line,8,description; (Need to remove the line) test the line,8,description="testing -- done"; (No need) test the line,8,description="testing -- done"; -- commented line (need to remove the words after the -- symbol) `open(FILE,"test.txt") or die $!; while($line=<FILE>){ $line=~s/-- .*//g; print "$line\n"; }` [download]	[reply] [d/l]