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 https://opensource.org/license/lgpl-2-1/.
 12 *
 13 * @author  Jon Parise <jon@horde.org>
 14 * @package Text_Diff
 15 */
 16class 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}
 65