Possible with a regex?

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

Hi,

I'm trying to find a solution to this. For some annoying reason, people have been using invalid BBCode, and I'm trying to fix this up. For example:

my $test = qq|
sdfiojs pfojsdfs fs [img]sdj fpsdofj spojf sfsf [b] [img]http://www.te
+st.com/image.gif[/img] dfs fs
s fsf sfd  [img]test.gif[/img]
|;

while ($test =~ /\[img\](.+?)\[\/img\]/g) {
   print "$1 \n";
}
[download]

..gives me:

C:\Users\Andy>perl test.pl
sdj fpsdofj spojf sfsf [b] [img]http://www.test.com/image.gi
test.gif
[download]

What I need really, is:

C:\Users\Andy>perl test.pl
http://www.test.com/image.gif
test.gif
[download]

Is this possible? I could do it inside the while () loop, by checking the value - but if possible, I would prefer to just do it in a regex :)

TIA

Andy

Comment on Possible with a regex? Select or Download Code

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Re: Possible with a regex? by BrowserUk (Patriarch) on May 23, 2011 at 15:43 UTC
If you can assume that urls will not contain (unencoded) spaces, then this might work for you: `my $test = qq\| sdfiojs pfojsdfs fs [img]sdj fpsdofj spojf sfsf [b] [img]http://www.te +st.com/image.gif[/img] dfs fs s fsf sfd [img]test.gif[/img] \|; while ($test =~ /\[img\](\S+?)\[\/img\]/g) { print "$1 \n"; } __END__ c:\test>junk http://www.test.com/image.gif test.gif` [download] Alternatively, maybe this is better: `while ($test =~ /\[img\]([^\[\]]+?)\[\/img\]/g) { print "$1 \n"; }` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^2: Possible with a regex? by ultranerds (Hermit) on May 23, 2011 at 15:51 UTC
Hi, Thanks - your second option works perfectly :) Cheers Andy	[reply]
Re: Possible with a regex? by Corion (Patriarch) on May 23, 2011 at 15:49 UTC
Depending on how much you can limit your input, one easy way would be to disallow `[` in your URLs: `while ($test =~ m!\[img\]([^\[]+)\[\/img\]!g) { print "$1 \n"; }` [download] If you really want to allow `[` and `]` in your tags as well, you can, I think, create some complex look-ahead regex that disallows for `[img]` to appear, by allowing for `[` if it's not followed by `i` and allowing `[i` if it's not followed by `m` and allowing `[im` if it's not followed by `g` and so on: `while ($test =~ m!\[img\]((?:[^\[]+\|\[[^i]\|\[i[^m]\|\[im[^g]\|...)+\[\/i +mg\]!g) { print "$1 \n"; }` [download] Personally, I would restrict the input to disallow `[` in URLs or just split on `/\[img\]/` and then discard all strings that don't contain `[/img]`.	[reply] [d/l] [select]
Re^2: Possible with a regex? by ultranerds (Hermit) on May 23, 2011 at 15:55 UTC
Thanks. Images can only use a valid image URL (as well as "dynamic URLs" .. i.e image.cgi?sess=234wfdsfsf) ... so the more basic version works for me :)	[reply]
Re: Possible with a regex? by wind (Priest) on May 23, 2011 at 17:10 UTC
Note: try using m{...} instead of m/.../ anytime you want to have a regex that contains forward slashes. That way you don't have to escape them: `my $test = qq\| sdfiojs pfojsdfs fs [img]sdj fpsdofj spojf sfsf [b] [img]http://www.te +st.com/image.gif[/img] dfs fs s fsf sfd [img]test.gif[/img] \|; while ($test =~ m{\[img\]([^\[\]]*)\[/img\]}g) { print "$1\n"; }` [download]	[reply] [d/l]
Re: Possible with a regex? by John M. Dlugosz (Monsignor) on May 23, 2011 at 17:40 UTC
There should already be modules on CPAN that parse or convert BBCode.	[reply]
Re: Possible with a regex? by JavaFan (Canon) on May 23, 2011 at 19:11 UTC
Some basic loop-unrolling: (untested) `m{\[img]([^[](?:\[(?!img])[^[])*)\[/img]}g` [download]	[reply] [d/l]