$re = '/\$\{\s*(?<path>[a-zA-Z_$]\w*(?:\.[a-zA-Z_$]\w*)*)\s*\}/';
$str = 'Hello, ${ name } Hello, ${ 0name } Hello, { name }
Hello, ${ _name_01 } Hello, ${ name$ } Hello, ${ _name_01 }
Hello, ${ $_name_2 }
Hello, ${ user.name.first } ${ user.name.last }!
Hello, ${ type.user.name.first.f1 } { type.user.name.last }!
Hello, ${ type.0user.name.first.f1 } ${ type.$user.name.last }!
Hello, ${ type.$user0._name_.first.f1 } ${ type.user$.name.last }!
';
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