从PHP中的preg_split获取分隔符

我的 PHP代码：

$cmd = 'SELECT var1 FROM var2 GROUP BY var3 LIMIT var4';
// split command
$p = preg_split('/SELECT|FROM|GROUP BY|LIMIT/si',$cmd);

输出：

Array
(
  [0] =>  
  [1] =>  var1 
  [2] =>  var2 
  [3] =>  var3
  [4] =>  var4
)

以下输出可能吗？

Array
(
  [SELECT] => var1
  [FROM] => var2
  [GROUP BY] => var3
  [LIMIT] => var4
)

或者有没有办法获得分隔符？

解决方法

$cmd = 'SELECT var1 FROM var2 GROUP BY var3 LIMIT var4';

$array = array();
if(preg_match_all('/(SELECT|FROM|GROUP BY|LIMIT)\s+([^\s]+)/si',$cmd,$matches)) {
    $array = array_combine($matches[1],$matches[2]);
}

var_dump($array);

结果：

array
  'SELECT' => string 'var1' (length=4)
  'FROM' => string 'var2' (length=4)
  'GROUP BY' => string 'var3' (length=4)
  'LIMIT' => string 'var4' (length=4)