บทที่ 35 RSS parser

<?
header('content-type: text/plain');

// define hooks to rss_parser class as xml functions do not allow object methods as handlers.
function rss_start_element($parser, $name, $attributes) {
  global $rss;
  $rss->start_element($parser, $name, $attributes);
}

function rss_end_element($parser, $name) {
  global $rss;
  $rss->end_element($parser, $name);
}

function rss_character_data($parser, $data) {
  global $rss;
  $rss->character_data($parser, $data);
}

class rss_parser {

  // constructor. setup parser options and handlers.
  function rss_parser() {
    $this->error = '';
    $this->file = '';

    $this->channel = array();
    $this->data = '';
    $this->stack = array();
    $this->num_items = 0;

    $this->xml_parser = xml_parser_create();
    xml_set_element_handler($this->xml_parser, "rss_start_element", "rss_end_element");
    xml_set_character_data_handler($this->xml_parser, "rss_character_data");
  }

  function character_data($parser, $data) {
    if (empty($this->data)) $this->data = trim($data); // concatenate non-parsed data...
    else $this->data .= ' '.trim($data); // and get rid of white space.
  }

  function start_element($parser, $name, $attrs) {
    switch($name) {
    case 'RSS':
      break;

    case 'CHANNEL':
      break;

    case 'IMAGE':
      array_push($this->stack, $name);
      break;

    case 'ITEM':
      array_push($this->stack, $name);
      array_push($this->stack, $this->num_items); // push item index.
      $this->item[$this->num_items] = array();
      $this->num_items++;
      break;

    case 'TEXTINPUT':
      array_push($this->stack, $name);
      break;

    default:
      array_push($this->stack, $name);
      break;
    }
  }

  function end_element($parser, $name) {
    switch ($name) {
    case 'RSS':
      break;

    case 'CHANNEL':
      break;

    case 'IMAGE':
      array_pop($this->stack);
      break;

    case 'ITEM':
      array_pop($this->stack);
      array_pop($this->stack);
      break;

    case 'TEXTINPUT':
      array_pop($this->stack);
      break;

    default: // child element.
      $element = (implode("']['",$this->stack));
      eval("$this->channel['$element']=$this->data;"); // this does all the hard work.
      array_pop($this->stack);
      $this->data = '';
      break;
    }
  }


  function parse() {
    if (!($fp = @fopen($this->file, "r"))) {
      $this->error = "Could not open RSS source \"$this->file\".";
      return false;
    }
    while ($data = fread($fp, 4096)) {
      if (!xml_parse($this->xml_parser, $data, feof($fp))) {
        $this->error = sprintf("XML error: %s at line %d.",
        xml_error_string(xml_get_error_code($this->xml_parser)),
        xml_get_current_line_number($this->xml_parser));
        return false;
      }
    }
    xml_parser_free($this->xml_parser);
    return true;
  }

} // class rss_parser.

// try it out...
$rss = new rss_parser();
$rss->file = 'http://freebsddiary.org/news.php3';
$rss->parse() or die($rss->error);
if ($rss->error) print $rss->error;

print_r($rss->channel); // PHP 4 needed for this to work.
?>