怎样根据$hello数据将$str层层展开？解决方案

<?php    $my_arr=array();    $str="DIR_FS_AAA . DIR_WS_CLASSES";    $hello=array(        "DIR_FS_AAA"     =>"DIR_WS_TEMPLATE.'includes/'",        "DIR_WS_CLASSES"    =>"DIR_WS_ADMIN.'helloworld'",        "DIR_WS_TEMPLATE"    =>"template/",        "DIR_WS_ADMIN"        =>"admin/"    );//怎样得到这样的结果数组：     $my_arr=array(         "DIR_FS_AAA . DIR_WS_CLASSES",         "DIR_WS_TEMPLATE.'includes/'.DIR_WS_TEMPLATE.'includes/'",         "template/includes/admin/includes/"     );?>

$my_arr[]    = $str;$tmp    = preg_replace("/[A-Z_]+/e", "\$hello['\\0']", $str);$my_arr[]    = $tmp;$tmp    = preg_replace("/[\"']?\s*\.?\s*([A-Z_]+)\s*\.?\s*[\"']/e", "\$hello['\\1']", $tmp);$my_arr[]    = $tmp;//testprint_r($my_arr);/**Array(    [0] => DIR_FS_AAA . DIR_WS_CLASSES    [1] => DIR_WS_TEMPLATE.'includes/' . DIR_WS_ADMIN.'helloworld'    [2] => template/includes/admin/helloworld')/**/