hi all,

i need some regex to get over this situation.

i couldnt figure it out myself so if you can help me, that would be great.

my problem is that i need to extract some tags. for example;

bla bla bla {{ tag starts here {{ internal tag }} and it continues.. }} like this..

I need to extract :

{{ tag starts here {{ internal tag }} and it continues.. }}

portions of the text but i get results like this:

{{ tag starts here {{ internal tag }}

when the regex sees the }} it ends up there.

Does it have a solution in regex? 

Traditionally the simple answer to your question is 'no' because regex's cannot count (in this case, count the number of {{'s and match until you ge to the same number of }}'s ).

However, there are some extensions that can help you here but only in some languages and regex engines. Specifically, the .NET based regex engine can do this by having  what are called balanced groups, and PCRE can do this by defining a recursion on the appropriate part of the pattern. Perl allows you to execute your own custom code in the middle of the pattern matching process and so you can add the necessary code for yourself. Google will find several generic examples of each of these techniques.

However, without knowing more about your specific situation we can't help you much further. Please see the posting guildelines (the 'sticky' note at the top of this forum) as to what you need to tell us.

Susan

bla bla bla {{ tag starts here {{ internal tag }} and it continues.. }} like this..

\{{2}(?:[^{}]++|(?R))*\}{2}

ddrudik's answer will work for nested tags of any depth. It is only limited by the memory available for the PCRE stack.

Susan 

tpaksu:

WOW! I think this will work only a tag is in a tag, if there's a third tag, this will not work.. But I think this will work for all the situations in my script. Thank you very very much! And Susan thank you too for your interest.

bla bla bla {{ tag starts here and it continues.. }} like this..
bla bla bla {{ tag starts here {{ internal tag }} and it continues.. }} like this..
bla bla bla {{ tag starts here {{ internal tag }} and it continues.. tag starts here {{ internal tag }}  }} like this..
bla bla bla {{ tag starts here {{ internal tag }} and it continues.. tag starts here {{ tag starts here {{ internal tag }} internal tag }} }} like this..