$re = '/\(\s*;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?\s*(?:;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?(?:\s*;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?)*)?\s*(?:\((?:;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?(?:\s*;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?)*)?\)(?:\((?:;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?(?:\s*;(?:[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*(?:\s*[A-Z](?:\s*[A-Z])*\s*\[(?:\\\\\]|[^\]])*\](?:\s*\[(?:\\\\\]|[^\]])*\])*)*)?)*)?\))*)?\s*\)/';
$str = '(;GM[1]FF[4]CA[UTF-8]AP[Sabaki:0.52.2]KM[6.5]SZ[19]DT[2023-12-25];B[pd];W[dd];B[pq];W[dp])
(;GM[1]FF[4]CA[UTF-8]AP[Sabaki:0.52.2]KM[6.5]SZ[19]DT[2023-12-25];B[pd];W[dd](;B[pq];W[dp])(;B[dp];W[pp]))
(;GM[1]FF[4]CA[UTF-8]AP[Sabaki:0.52.2]KM[6.5]SZ[19]DT[2023-12-25];B[pd];W[dd](;B[pq];W[dp])(;B[dp];W[pp];PL[B]AE[jk]AB[jj]AW[ji];B[jq]))
(;GM[1]FF[4]CA[UTF-8]AP[Sabaki:0.52.2]KM[6.5]SZ[19]DT[2023-12-25];B[pd]C[Comment on move.];W[dd](;B[pq];W[dp])(;B[dp];W[pp];PL[B]AE[jk]AB[jj]AW[ji]C[Comment on editing.];B[jq]))';
preg_match_all($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