$re = '/^(?\'EXPR\'(\+\+|--|\+|-|\*|\&|~|!)?\s*(((-?(?(?=0[xX])0[xX][\da-fA-F]+\.[\da-fA-F]|\d+\.\d*))|(-?(?(?=0)0(?(?=[xX]).[\da-fA-F\']+|(?(?=[bB]).[01\']+|[0-7\']))|[\d\']+))|(\'\\\\?.{1,4}\')|((L|u8|u16|u32|(?:))"((\\\\\\\\)*\\\\"|[^"])*")|(R"(?\'OPENING\'.*)\(.*\)\g{OPENING}"))(\s*[\w$][\w\d$]*)?|[\w$][\w\d$]*(::[\w$][\w\d$]*)*)((\s*\+\+|--)|(\s*([+\-*\/%<>&|]|(\<\<|\>\>|\&\&|\|\|\<=|\>=|==|!=))\s*(?&EXPR))|(\(((?&EXPR)(\s*,\s*(?&EXPR))*)?\))|(\<((?&EXPR)(\s*,\s*(?&EXPR))*)?\>)|(\[(?&EXPR)\]))*)$/m';
$str = '';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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