Pattern matching css rules - php

Question

I have the following pattern:
[\{\}].*[\{\}]
With the following test strings (can provide more if needed):
}.prop{hello:ars;} //shouldn't match
}#prop{} //should match
}.prop #prop {} //should match
The purpose of the pattern is to find empty css rulesets. Can someone suggest how I go about excluding matches with characters between the second set of brackets? I will be updating the pattern as I get closer to a solution.
edit:
on http://gskinner.com/RegExr/
this pattern: [\}].*[\{]{1}[/}]{1}
seems to have the desired result although it is breaking when transfered to php for reasons I don't understand.
edit:
first apologies if this should be a separate question.
Using the pattern in the first edit in php:
$pattern = "/[\}].*[\{]{1}[/}]{1}/";
preg_match_all ($pattern, $new_css, $p);
print_r($p);
When $new_css is a string of the content of an uploaded css file containing empty rulesets, $p is never populated. Yet I know this pattern is ok. Can anyone see what the issue is?
edit: final solution
//take out other unwanted characters
$pattern = "/\}([\.#\w]\w+\s*)+{}/";
//do it twice to beat any deformation
$new_css = preg_replace ($pattern, '}', $new_css);
$new_css = preg_replace ($pattern, '}', $new_css);

Answer 1

Try using single quotes around the regex, or doubling the \ characters. The way PHP handles \ in double-quoted strings is that \{ becomes {, breaking the regex.

Answer 2

Try the pattern: '/}([\.#]\w+\s*)+{}/'
$new_css = "{}.prop{hello:ars;}
{}#prop{} //should match
}.prop #prop {} //should match
}.prop { aslkdfj}
}.prop { }
";
$pattern = '/}([\.#]\w+\s*)+{}/';
preg_match_all ($pattern, $new_css, $p);
print_r($p);
This outputs:
Array
(
[0] => Array
(
[0] => }#prop{}
[1] => }.prop #prop {}
)
[1] => Array
(
[0] => #prop
[1] => #prop
)
)