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 2004-2010 The Horde Project (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://opensource.org/licenses/lgpl-license.php.

    12  *

    13  * @author  Jon Parise <jon@horde.org>

    14  * @package Text_Diff

    15  */

    16 class Text_Diff_Engine_xdiff {

    17 

    18     /**

    19      */

    20     function diff($from_lines, $to_lines)

    21     {

    22         array_walk($from_lines, array('Text_Diff', 'trimNewlines'));

    23         array_walk($to_lines, array('Text_Diff', 'trimNewlines'));

    24 

    25         /* Convert the two input arrays into strings for xdiff processing. */

    26         $from_string = implode("\n", $from_lines);

    27         $to_string = implode("\n", $to_lines);

    28 

    29         /* Diff the two strings and convert the result to an array. */

    30         $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));

    31         $diff = explode("\n", $diff);

    32 

    33         /* Walk through the diff one line at a time.  We build the $edits

    34          * array of diff operations by reading the first character of the

    35          * xdiff output (which is in the "unified diff" format).

    36          *

    37          * Note that we don't have enough information to detect "changed"

    38          * lines using this approach, so we can't add Text_Diff_Op_changed

    39          * instances to the $edits array.  The result is still perfectly

    40          * valid, albeit a little less descriptive and efficient. */

    41         $edits = array();

    42         foreach ($diff as $line) {

    43             if (!strlen($line)) {

    44                 continue;

    45             }

    46             switch ($line[0]) {

    47             case ' ':

    48                 $edits[] = new Text_Diff_Op_copy(array(substr($line, 1)));

    49                 break;

    50 

    51             case '+':

    52                 $edits[] = new Text_Diff_Op_add(array(substr($line, 1)));

    53                 break;

    54 

    55             case '-':

    56                 $edits[] = new Text_Diff_Op_delete(array(substr($line, 1)));

    57                 break;

    58             }

    59         }

    60 

    61         return $edits;

    62     }

    63 

    64 }