Re: Search for consecutive flush left curly braces

[stevieb]

This regex: /}.*(?!{)}/ will do what you want I believe.

It'll match }} and }adfa} but not }{} or }asdf{asdf} etc.

[QM]

Won't that mach a right-curly, followed by any-number-of-any-characters, followed by not-a-left-curly? Isn't a left-curly included in any-number-of-any-characters?

[stevieb]

No, at least not as how I understand it. The (?!{) is a negative-lookahead, meaning match any characters non-greedily as long as they do NOT contain a {, before the next }.

If I'm wrong, someone will inform me ;)

[Athanasius]

OK, you’re wrong. SCNR. :-)

First off, for the reason given by QM, this regex doesn’t prevent a match if there is a { character between } characters:

 2:57 >perl -wE "my $s = '}abc{def}'; say 'match' if $s =~ /}.*(?!{)}/
+;"
match

 2:59 >

Second, there is no non-greedy match here: .* is greedy. But making it non-greedy doesn’t help:

 2:59 >perl -wE "my $s = '}abc{def}'; say 'match' if $s =~ /}.*?(?!{)}
+/;"
match

 2:59 >

A negated character class is what is needed:

 3:31 >perl -wE "my $s = '}abc{def}'; say 'match' if $s =~ /}[^{]*?}/;
+"

 3:31 >perl -wE "my $s = '}abc|def}'; say 'match' if $s =~ /}[^{]*?}/;
+"
match

 3:31 >

Hope that helps,

Update: Tweaked the third code snippet.

[ExReg]

I guess I was unclear in my original post. I am dealing with multiple lines slurped up into a single string. The curlies I am looking for will have \n embedded in the string before them, so I have to use either \n or ^ in the expression along with s and m modifiers.