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   1  <?php
   2  /**
   3   * Class used internally by Diff to actually compute the diffs.
   4   *
   5   * This class uses the xdiff PECL package (http://pecl.php.net/package/xdiff)
   6   * to compute the differences between the two input arrays.
   7   *
   8   * Copyright 2004-2011 Horde LLC (http://www.horde.org/)
   9   *
  10   * See the enclosed file COPYING for license information (LGPL). If you did
  11   * not receive this file, see http://www.horde.org/licenses/lgpl21.
  12   *
  13   * @author  Jon Parise <jon@horde.org>
  14   * @package Text_Diff
  15   */
  16  
  17  // Disallow direct access to this file for security reasons
  18  if(!defined("IN_MYBB"))
  19  {
  20      die("Direct initialization of this file is not allowed.<br /><br />Please make sure IN_MYBB is defined.");
  21  }
  22  
  23  class Horde_Text_Diff_Engine_Xdiff
  24  {
  25      /**
  26       */
  27      public function diff($from_lines, $to_lines)
  28      {
  29          if (!extension_loaded('xdiff')) {
  30              throw new Horde_Text_Diff_Exception('The xdiff extension is required for this diff engine');
  31          }
  32  
  33          array_walk($from_lines, array('Horde_Text_Diff', 'trimNewlines'));
  34          array_walk($to_lines, array('Horde_Text_Diff', 'trimNewlines'));
  35  
  36          /* Convert the two input arrays into strings for xdiff processing. */
  37          $from_string = implode("\n", $from_lines);
  38          $to_string = implode("\n", $to_lines);
  39  
  40          /* Diff the two strings and convert the result to an array. */
  41          $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));
  42          $diff = explode("\n", $diff);
  43  
  44          /* Walk through the diff one line at a time.  We build the $edits
  45           * array of diff operations by reading the first character of the
  46           * xdiff output (which is in the "unified diff" format).
  47           *
  48           * Note that we don't have enough information to detect "changed"
  49           * lines using this approach, so we can't add Horde_Text_Diff_Op_Changed
  50           * instances to the $edits array.  The result is still perfectly
  51           * valid, albeit a little less descriptive and efficient. */
  52          $edits = array();
  53          foreach ($diff as $line) {
  54              if (!strlen($line)) {
  55                  continue;
  56              }
  57              switch ($line[0]) {
  58              case ' ':
  59                  $edits[] = new Horde_Text_Diff_Op_Copy(array(substr($line, 1)));
  60                  break;
  61  
  62              case '+':
  63                  $edits[] = new Horde_Text_Diff_Op_Add(array(substr($line, 1)));
  64                  break;
  65  
  66              case '-':
  67                  $edits[] = new Horde_Text_Diff_Op_Delete(array(substr($line, 1)));
  68                  break;
  69              }
  70          }
  71  
  72          return $edits;
  73      }
  74  }