Recursive regex in Perl

Question

I've got strings like these: | Released = {{start-date|June 14, 1972}} | Released = {{Start date|1973|03|01|df=y}} I'd like to replace all | within {{ }} with ^ | Released = {{start-date^June 14, 1972}} | Released = {{Start date^1973^03^01^df=y}} I can't use substring replacement because there are | symbols outside {{ }}, which must be left intact. And because I don't know exactly how many parts does the string in {{ }} have, I can't use something like s/{{(.+?)\|(.+?)}}/{{$1^$2}}/. I suppose I need to use some kind of recursion here? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

A simple solution: s/\|(?=[^{}\n]*}})/^/g Even simpler solution, but probably broken in many cases: s/(?!^)\|/^/gm Here is a bit more robust regex: s/(?:\G(?!^)(?:(?>[^|]*?}})(?>.*?{{))*|^(?>.*?{{))(?>[^|]*?(?=}}|\|))\K\|(?=.*?}})/^/gs; Commented: s/ (?: \G(?!^) # inside of a {{}} tag (?: (?>[^|]*?}}) (?>.*?{{) )* # read till we find a | in another tag if none in current | ^(?>.*?{{) # outside of tag, parse till in ) (?> [^|]*? (?=}}|\|) ) # eat till a | or end of tag \K # don't include stuff to the left of \K in the match \| # the | (?=.*?}}) # just to make sure the tag is closed /^/gsx; Input: |}} | Re|eased = {{start-date|June 14^, {|1972}|x}} | Released = {{Start date}|1973|03|01}|df=y|}} | || {{|}} {{ | Output: |}} | Re|eased = {{start-date^June 14^, {^1972}^x}} | Released = {{Start date}^1973^03^01}^df=y^}} | || {{^}} {{ | Example: http://ideone.com/fbY2W