class DrupalDiffFormatter

class DrupalDiffFormatter extends DiffFormatter {
  var $rows;
  var $line_stats = array(
    'counter' => array(
      'x' => 0,
      'y' => 0,
    ),
    'offset' => array(
      'x' => 0,
      'y' => 0,
    ),
  );
  function DrupalDiffFormatter() {
    $this->leading_context_lines = variable_get('diff_context_lines_leading', 2);
    $this->trailing_context_lines = variable_get('diff_context_lines_trailing', 2);
  }
  function _start_diff() {
    $this->rows = array();
  }
  function _end_diff() {
    return $this->rows;
  }
  function _block_header($xbeg, $xlen, $ybeg, $ylen) {
    return array(
      array(
        'data' => theme('diff_header_line', array(
          'lineno' => $xbeg + $this->line_stats['offset']['x'],
        )),
        'colspan' => 2,
      ),
      array(
        'data' => theme('diff_header_line', array(
          'lineno' => $ybeg + $this->line_stats['offset']['y'],
        )),
        'colspan' => 2,
      ),
    );
  }
  function _start_block($header) {
    if ($this->show_header) {
      $this->rows[] = $header;
    }
  }
  function _end_block() {
  }
  function _lines($lines, $prefix = ' ', $color = 'white') {
  }

  /**
   * Note: you should HTML-escape parameter before calling this.
   */
  function addedLine($line) {
    return array(
      array(
        'data' => '+',
        'class' => 'diff-marker',
      ),
      array(
        'data' => theme('diff_content_line', array(
          'line' => $line,
        )),
        'class' => 'diff-context diff-addedline',
      ),
    );
  }

  /**
   * Note: you should HTML-escape parameter before calling this.
   */
  function deletedLine($line) {
    return array(
      array(
        'data' => '-',
        'class' => 'diff-marker',
      ),
      array(
        'data' => theme('diff_content_line', array(
          'line' => $line,
        )),
        'class' => 'diff-context diff-deletedline',
      ),
    );
  }

  /**
   * Note: you should HTML-escape parameter before calling this.
   */
  function contextLine($line) {
    return array(
      ' ',
      array(
        'data' => theme('diff_content_line', array(
          'line' => $line,
        )),
        'class' => 'diff-context',
      ),
    );
  }
  function emptyLine() {
    return array(
      ' ',
      theme('diff_empty_line', array(
        'line' => ' ',
      )),
    );
  }
  function _added($lines) {
    foreach ($lines as $line) {
      $this->rows[] = array_merge($this
        ->emptyLine(), $this
        ->addedLine(check_plain($line)));
    }
  }
  function _deleted($lines) {
    foreach ($lines as $line) {
      $this->rows[] = array_merge($this
        ->deletedLine(check_plain($line)), $this
        ->emptyLine());
    }
  }
  function _context($lines) {
    foreach ($lines as $line) {
      $this->rows[] = array_merge($this
        ->contextLine(check_plain($line)), $this
        ->contextLine(check_plain($line)));
    }
  }
  function _changed($orig, $closing) {
    $diff = new WordLevelDiff($orig, $closing);
    $del = $diff
      ->orig();
    $add = $diff
      ->closing();

    // Notice that WordLevelDiff returns HTML-escaped output.
    // Hence, we will be calling addedLine/deletedLine without HTML-escaping.
    while ($line = array_shift($del)) {
      $aline = array_shift($add);
      $this->rows[] = array_merge($this
        ->deletedLine($line), isset($aline) ? $this
        ->addedLine($aline) : $this
        ->emptyLine());
    }
    foreach ($add as $line) {

      // If any leftovers
      $this->rows[] = array_merge($this
        ->emptyLine(), $this
        ->addedLine($line));
    }
  }

}