Re: Regex conditional match if previous match in same expression is true?

The following doesn't use the (?() pat) construct but it does use a similar setup - and it prints out the correct output:

for (
    'oh {hello} there',
    'oh {hello there',
    'oh hello there',
    'oh hello} there',
) {
    our $paren;
    if (/
         ({ | (?<!{))                   # optional opening brace
         (?{ $paren = $^N })            # store for later
         hello                          # .. followed by 'hello'
         (??{$paren ? "\}" : "(?!\})"}) # a closing brace if the open 
+brace was there
        /x) {
        print "Yep - $1\n";
    } else {
        print "Nope\n";
    }
}
[download]

I tried briefly to get the (?() ) form to work but couldn't get it to go.

my @a=qw(random brilliant braindead); print $a[rand(@a)];

Comment on Re: Regex conditional match if previous match in same expression is true? Download Code

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Re^2: Regex conditional match if previous match in same expression is true? by ikegami (Patriarch) on Apr 09, 2007 at 19:48 UTC
~~That doesn't give me the desired results at all.~~ I was using Perl 5.6, but `$^N` was only introduced in 5.8. By the way, you should localize your package variables whenever possible. Replace `our $paren;` with `local our $paren;` I'd also add a comment along the lines of "Always use package variables with regular expressions." Someone reading or maintaining the code could very well not know that lexical variables can cause problems. Finally, to avoid continually compiling regexp fragments, replace `(??{$paren ? "\}" : "(?!\})"})` with `(?(?{ $paren }) } \| (?!}) )`	[reply] [d/l] [select]
Re^3: Regex conditional match if previous match in same expression is true? by demerphq (Chancellor) on Apr 10, 2007 at 17:30 UTC
Note that Rhandom and I basically posted the same pattern, the main difference being mine doesn't need the (?{})/(??{})/$^N stuff, using the conditional pattern instead (as you originally requested). Actually to be honest I didnt really look deeply at Rhandom's post before I posted mine. Its cool we came up with the same thing pretty much, but using two different advanced feature sets. --- $world=~s/war/peace/g	[reply]
Re^4: Regex conditional match if previous match in same expression is true? by ikegami (Patriarch) on Apr 10, 2007 at 17:37 UTC
Aye, I noticed that after I replied. I didn't mean to diminish your post. I basically stopped following the thread after Rhandom posted.	[reply]