$re = '/[:,\s]\s*url\s*\(\s*(?:\'(\S*?)\'|"(\S*?)"|((?:\\\\\s|\\\\\)|\\\\\"|\\\\\'|\S)*?))\s*\)/i';
$str = '.ac-gn-link-apple{background-repeat:no-repeat;background-size:20px 44px;background-image:url("../images/ac-globalnav/globalnav/apple/image_large.svg");background-position:center center;width:20px}#ac-globalnav.no-svg .ac-gn-link-apple{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/apple/image_large.png")}@media only screen and (max-width: 767px){#ac-globalnav .ac-gn-link-apple{background-size:21px 48px;background-image:url("../images/ac-globalnav/globalnav/apple/image_small.svg")}#ac-globalnav.no-svg .ac-gn-link-apple{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/apple/image_small.png")}}.ac-gn-current-apple #ac-globalnav .ac-gn-link-apple{opacity:0.65;-ms-filter:\'progid:DXImageTransform.Microsoft.Alpha(Opacity=$ieopacity)\';filter:alpha(opacity=65)}#ac-globalnav .ac-gn-link-mac{background-repeat:no-repeat;background-size:31px 44px;background-image:url("../images/ac-globalnav/globalnav/links/mac/image_large.svg");background-position:center center;background-origin:content-box;background-size:cover;width:1.72222em;max-width:52.7px}#ac-globalnav.no-svg .ac-gn-link-mac{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/links/mac/image_large.png")}@media only screen and (max-width: 767px){#ac-globalnav .ac-gn-link-mac{background-size:37px 48px;background-image:url("../images/ac-globalnav/globalnav/links/mac/image_small.svg")}#ac-globalnav.no-svg .ac-gn-link-mac{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/links/mac/image_small.png")}}.ac-gn-current-mac #ac-globalnav .ac-gn-link-mac{opacity:0.65;-ms-filter:\'progid:DXImageTransform.Microsoft.Alpha(Opacity=$ieopacity)\';filter:alpha(opacity=65)}#ac-globalnav .ac-gn-link-ipad{background-repeat:no-repeat;background-size:30px 44px;background-image:url("../images/ac-globalnav/globalnav/links/ipad/image_large.svg");background-position:center center;background-origin:content-box;background-size:cover;width:1.66667em;max-width:51px}#ac-globalnav.no-svg .ac-gn-link-ipad{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/links/ipad/image_large.png")}@media only screen and (max-width: 767px){#ac-globalnav .ac-gn-link-ipad{background-size:35px 48px;background-image:url("../images/ac-globalnav/globalnav/links/ipad/image_small.svg")}#ac-globalnav.no-svg .ac-gn-link-ipad{background-image:url("http://images.apple.com/ac/globalnav/2.0/en_US/images/ac-globalnav/globalnav/links/ipad/image_small.png")}}.ac-gn-current-ipad #ac-globalnav .ac-gn-link-ipad{opacity:0.65;-ms-filter:\'progid:DXImageTransform.Microsoft.Alpha(Opacity=$ieopacity)\';filter:alpha(opacit...
:url(asdawdw)
: url(asdawdw)
: url (asdawdw)
: url ( asdawdw)
: url ( asdawdw )
: url ( asdawdw )
:url(\'asdawdw\')
: url(\'asdawdw\')
: url (\'asdawdw\')
: url ( \'asdawdw\')
: url ( \'asdawdw\' )
: url ( \'asdawdw\' )
:url("asdawdw")
: url("asdawdw")
: url ("asdawdw")
: url ( "asdawdw")
: url ( "asdawdw" )
: url ( "asdawdw" )
:url(asda\\)wdw)
:url(asda\\))wdw) <- should terminate early, due to unescape paren
:url(asda\\ wdw)
:url(asda\\ wdw) <- unescape space, invalid
:url(asda\\"wdw)
:url(asda\\" wdw) <- unescape space, invalid
:url(asda\\\'wdw)
:url(asda\\\')wdw) <- should terminate early, due to unescape paren
: url ( "asda\\"wdw")
: url ( \'asda\\"wdw\')
: url ( \'asda\\)))wdw\')
: url ( \'asda\\"))wdw\')
: url ( asda\\"))wdw)';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php