class MappedDiff

class MappedDiff extends Diff {

  /**
   * Constructor.
   *
   * Computes diff between sequences of strings.
   *
   * This can be used to compute things like
   * case-insensitve diffs, or diffs which ignore
   * changes in white-space.
   *
   * @param $from_lines array An array of strings.
   *  (Typically these are lines from a file.)
   *
   * @param $to_lines array An array of strings.
   *
   * @param $mapped_from_lines array This array should
   *  have the same size number of elements as $from_lines.
   *  The elements in $mapped_from_lines and
   *  $mapped_to_lines are what is actually compared
   *  when computing the diff.
   *
   * @param $mapped_to_lines array This array should
   *  have the same number of elements as $to_lines.
   */
  function MappedDiff($from_lines, $to_lines, $mapped_from_lines, $mapped_to_lines) {
    assert(sizeof($from_lines) == sizeof($mapped_from_lines));
    assert(sizeof($to_lines) == sizeof($mapped_to_lines));
    $this
      ->Diff($mapped_from_lines, $mapped_to_lines);
    $xi = $yi = 0;
    for ($i = 0; $i < sizeof($this->edits); $i++) {
      $orig =& $this->edits[$i]->orig;
      if (is_array($orig)) {
        $orig = array_slice($from_lines, $xi, sizeof($orig));
        $xi += sizeof($orig);
      }
      $closing =& $this->edits[$i]->closing;
      if (is_array($closing)) {
        $closing = array_slice($to_lines, $yi, sizeof($closing));
        $yi += sizeof($closing);
      }
    }
  }

}