protected function prefetch()
    {
        $this->valid = true;
        $this->current = $this->iterator->current();
        $this->key = $this->iterator->key();

        $this->iterator->next();
        if ( !$this->iterator->valid() ) {
            $this->valid = false;
            $this->end = true;
        }
    }
protected function prefetch()
    {
        $this->valid = true;
        $this->current = $this->iterator->current();
        $this->key = $this->iterator->key();

        $this->iterator->next();
        if ( !$this->iterator->valid() ) {
            $this->valid = false;
            $this->end = true;
        }
    }
protected function prefetch ( ) { $ this -> valid = true ; $ this -> current = $ this -> iterator -> current ( ) ; $ this -> key = $ this -> iterator -> key ( ) ; $ this -> iterator -> next ( ) ; if ( ! $ this -> iterator -> valid ( ) ) { $ this -> valid = false ; $ this -> end = true ; } }
Fetches the next element from the source data store and
updates the end flag if needed.

@access protected
Fetches the next element from the source data store and updates the end flag if needed .