in reply to Re: Matching nested begin/ends
in thread Matching nested begin/ends

I again disagree. Delimited text is generally part of a larger document that needs to be processed. I can see your point that anchoring the regex is the best way to fully verify the text item's syntax. However, why would this be needed? The item must have followed some pattern to be extracted in the first place.

Also, /begin.*end/ will allow a begin followed by an end, which will allow an item like beginbeginend to pass with no problems; hence recursion is needed.

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Re: Matching nested begin/ends
by Abigail-II (Bishop) on Aug 05, 2002 at 10:08 UTC
    Also, /begin.*end/ will allow a begin followed by an end, which will allow an item like beginbeginend to pass with no problems;
    So does your regex: 
    $re = /begin
       (?:
          (?>[^be]*)
         |(??{ $re })
         | [be]
        )*
        end/x;
"begin begin end" =~ /$re/ and print "<$&>\n";
__END__
<begin begin end>

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