Similarity checker

class Similarity
{
    protected $data = null;
    protected $distance = null;

    public function __construct($data, $distance)
    {
        $this->data     = (string)$data;
        $this->distance = (int)$distance;
    }

    public function checkMatch($search, callable $checker=null, array $args=[], $return=false)
    {
       $data   = preg_split('/\s+/', strtolower($this->data), -1, PREG_SPLIT_NO_EMPTY);
       $search = trim(preg_replace('/\s+/', ' ', strtolower($search)));
       foreach($this->getAssoc($data, substr_count($search, ' ')+1) as $assoc)
       {
           foreach($this->getPermutations($assoc) as $ordered)
           {
               $ordered = join(' ', $ordered);
               $result  = call_user_func_array($checker, array_merge([$ordered, $search], $args));
               if($result<=$this->distance)
               {
                   return $return?$ordered:true;
               }
           }
       }

       return $return?null:false;
    }

    protected function getPermutations(array $input)
    {
       if(count($input)==1)
       {
          return [$input];
       }
       $result = [];
       foreach($input as $key=>$element)
       {
          foreach($this->getPermutations(array_diff_key($input, [$key=>0])) as $subarray)
          {
             $result[] = array_merge([$element], $subarray);
          }
       }
       return $result;
    }

    protected function nextAssoc($assoc)
    {
       if(false !== ($pos = strrpos($assoc, '01')))
       {
          $assoc[$pos]   = '1';
          $assoc[$pos+1] = '0';
          return substr($assoc, 0, $pos+2).
                 str_repeat('0', substr_count(substr($assoc, $pos+2), '0')).
                 str_repeat('1', substr_count(substr($assoc, $pos+2), '1'));
       }
       return false;
    }

    protected function getAssoc(array $data, $count=2)
    {
       if(count($data)<$count)
       {
          return null;
       }
       $assoc   = str_repeat('0', count($data)-$count).str_repeat('1', $count);
       $result = [];
       do
       {
          $result[]=array_intersect_key($data, array_filter(str_split($assoc)));
       }
       while($assoc=$this->nextAssoc($assoc));
       return $result;
    }
}