Tough regular expression question

[dnmilne]

Hi there,

I've been struggling with this seemingly simple regular expression problem. I'm hoping someone can show me how dumb I've been:

take the string {{aaa{{bbb}}ccc}}

What I need is a regex that would match the {{bbb}} part, but not the whole thing. Basically, anything in double brackets as long as it doesnt have nested stuff in double brackets within it. The tricky part is that its allowed to contain single brackets.

Some examples:
{{aa}} - want to match "aaa"
{{aaa{{bbb}}}} - want to match "bbb" (not "aaa{{bbb"!!!)
{{aaa{{bbb}}ccc}} - still want to match "bbb"
{{aaa{{b{bb}}ccc}}- want to match "b{bb"

Any suggestions?

 

[spookie]

Hi,

Try

$str =~ /^\{\{.+\{{2}(.+)?\}(2).+$/ ;
print $1 ;

ps: Not Tested.

--------------------------------------------------------------------------
I never set a goal because u never know whats going to happen tommorow.

 

[prex1]

This one

regexp {{{(\w*?{?\w*?}?\w*?)}}} $string -> result

will match as you require with 0 or 1 (not more) single open braces and subsequent 0 or 1 single closed braces embedded within the innermost sequence of word chars contained within double open and closed braces.
Your definition and examples were not sufficiently well defined to insure that this is exactly what you were looking for, but it works for the examples provided.

Franco

http://www.xcalcs.com

: Online tools for structural design

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[prex1]

Oops, thought I was in the Tk forum.
The equivalent for perl is of course

$str=~/\{\{(\w*?\{?\w*?\}?\w*?)\}\}/;
print$1;

Franco

http://www.xcalcs.com

: Online tools for structural design

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[MillerH]

Check out the following:

[url=http://perldoc.perl.org/functions/use.html][black][b]use[/b][/black][/url] [green]strict[/green][red];[/red]

[olive][b]while[/b][/olive] [red]([/red]<DATA>[red])[/red] [red]{[/red]
	[url=http://perldoc.perl.org/functions/my.html][black][b]my[/b][/black][/url] [blue]$str[/blue] = [blue]$_[/blue][red];[/red]
	
	[url=http://perldoc.perl.org/functions/print.html][black][b]print[/b][/black][/url] [blue]$str[/blue][red];[/red]
	
	[olive][b]if[/b][/olive] [red]([/red][blue]$str[/blue] =~ [red]m/[/red][purple][purple][b]\{[/b][/purple][purple][b]\{[/b][/purple]([/purple]
[purple]		(?:[/purple]
[purple]			[^{}]+[/purple]
[purple]		|[/purple]
[purple]			[purple][b]\{[/b][/purple](?![purple][b]\{[/b][/purple])[/purple]
[purple]		|[/purple]
[purple]			[purple][b]\}[/b][/purple](?![purple][b]\}[/b][/purple])[/purple]
[purple]		)*[/purple]
[purple]		)[purple][b]\}[/b][/purple][purple][b]\}[/b][/purple][/purple]
[purple]	[/purple][red]/[/red][red]sx[/red][red])[/red] [red]{[/red]
		[black][b]print[/b][/black] [red]"[/red][purple][purple][b]\t[/b][/purple]Matches '[blue]$1[/blue]'[purple][b]\n[/b][/purple][/purple][red]"[/red][red];[/red]
	[red]}[/red] [olive][b]else[/b][/olive] [red]{[/red]
		[black][b]print[/b][/black] [red]"[/red][purple][purple][b]\t[/b][/purple]Doesn't Match[purple][b]\n[/b][/purple][/purple][red]"[/red][red];[/red]
	[red]}[/red]
[red]}[/red]

[teal]__DATA__[/teal]
[teal]{{aa}}            - want to match "aaa"[/teal]
[teal]{{aaa{{bbb}}}}    - want to match "bbb" (not "aaa{{bbb"!!!)[/teal]
[teal]{{aaa{{bbb}}ccc}} - still want to match "bbb"[/teal]
[teal]{{aaa{{b{bb}}ccc}}- want to match "b{bb" [/teal]
[teal]{{aaa{{b{b}b}}ccc}}- want to match "b{bb" [/teal]

[tt]------------------------------------------------------------
Pragmas (perl 5.10.0) used :
[ul]
[li]strict - Perl pragma to restrict unsafe constructs[/li]
[/ul]
[/tt]

- Miller