$re = '/({})\1|[{](|\s*?[^\s{}]+?\s*?|\s*?\S+?\(.*?\)\s*?|\s*?[\'][^\']+?[\']\s*?|\s*?["][^"]+?["]\s*?|\s*?["][^"]+?["]\.\S+?\(.*?\)\s*?|\s*?[\'][^\']+?[\']\.\S+?\(.*?\)\s*?)(?:!(\S+?))?[}]/';
$str = '{k} must-match
{} jhtgj {} must-match
{ } not-match
\'"{firstName} {lastName}" <{email}>\'
{0.concat("8a b c d e", 6)} must-match
s df s sd{"one fielslkein 897sd\'f8\'97f 89s(*Y*&Sc {}d name".toFixed(7 , 8)} must-match
s df s sd{\'one fielslkein "897sd"f897f 89s(*Y*&Sc {}d name\'.toFixed(7 , 8)} must-match
sd{0.concat("8a b c d e", 6)} must-match
ascdac{ "one fieldname" } must-match
ascdac{ "onefi eldname".kk(kk, "dd") } must-match
{onefieldname.toFixed(7 , 8)} must-match
dfgsdg { "onefieldname".toFixed(7 , 8)} must-match
{onefieldname: "toFixed(7 , 8)"} not-match
{"onefieldname": "toFixed(7 , 8)"} not-match
{ "onefiel dname" : "toFixed(7 , 8)"} not-match
{ "onefiel dname": 8} not-match
{ "o dna" : {onefi eldname.l(7 , 8)} } not-match
{ "o dna" : {"onefi eldname".l(7 , 8)} } match-inner
{ "f dna" : {"onefi eldname".toFixed(7 , 8) }} match-inner
{ "f dna" : { "onefi eldname".toFixed(7 , 8) }} match-inner
{ "o dme" : {onefieldname.toFixed(7 , 8)} } match-inner
{ "on dname" : { onefieldname.toFixed(7 , 8)} } match-inner
{ {}: "{}" }';
preg_match_all($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