using php array

<?php
function block_split($s){
 $pos = strpos($s,'[');
 $has_b = is_int($pos);
 if ($has_b){
  $a = array();
  $test = preg_match_all('/(\[[^]]*\])([^[]*)/s',$s,$ms,PREG_SET_ORDER);
  foreach($ms as $m){
   $a[] = $m[1];
   $a[] = $m[2];
  }
  array_unshift($a, substr($s,0,$pos));
 } else {
  $a = array($s);
 }
 $a = array_map('trim',$a);
 $a = array_diff($a,array(''));
 $a = array_values($a);
 return $a;
}

$s = 'xxx [metal] [plating] pine apple [test] test';
$a = block_split($s);
echo '<pre>',var_export($a,true),'</pre>';


?>