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 2004-2012 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: class Horde_Text_Diff_Engine_Xdiff
17: {
18:     /**
19:      */
20:     public function diff($from_lines, $to_lines)
21:     {
22:         if (!extension_loaded('xdiff')) {
23:             throw new Horde_Text_Diff_Exception('The xdiff extension is required for this diff engine');
24:         }
25: 
26:         array_walk($from_lines, array('Horde_Text_Diff', 'trimNewlines'));
27:         array_walk($to_lines, array('Horde_Text_Diff', 'trimNewlines'));
28: 
29:         /* Convert the two input arrays into strings for xdiff processing. */
30:         $from_string = implode("\n", $from_lines);
31:         $to_string = implode("\n", $to_lines);
32: 
33:         /* Diff the two strings and convert the result to an array. */
34:         $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));
35:         $diff = explode("\n", $diff);
36: 
37:         /* Walk through the diff one line at a time.  We build the $edits
38:          * array of diff operations by reading the first character of the
39:          * xdiff output (which is in the "unified diff" format).
40:          *
41:          * Note that we don't have enough information to detect "changed"
42:          * lines using this approach, so we can't add Horde_Text_Diff_Op_Changed
43:          * instances to the $edits array.  The result is still perfectly
44:          * valid, albeit a little less descriptive and efficient. */
45:         $edits = array();
46:         foreach ($diff as $line) {
47:             if (!strlen($line)) {
48:                 continue;
49:             }
50:             switch ($line[0]) {
51:             case ' ':
52:                 $edits[] = new Horde_Text_Diff_Op_Copy(array(substr($line, 1)));
53:                 break;
54: 
55:             case '+':
56:                 $edits[] = new Horde_Text_Diff_Op_Add(array(substr($line, 1)));
57:                 break;
58: 
59:             case '-':
60:                 $edits[] = new Horde_Text_Diff_Op_Delete(array(substr($line, 1)));
61:                 break;
62:             }
63:         }
64: 
65:         return $edits;
66:     }
67: }
68: