1<?php
  2/**
  3 * Class used internally by Diff to actually compute the diffs.
  4 *
  5 * This class uses the Unix `diff` program via shell_exec to compute the
  6 * differences between the two input arrays.
  7 *
  8 * Copyright 2007-2010 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  Milian Wolff <mail@milianw.de>
 14 * @package Text_Diff
 15 * @since   0.3.0
 16 */
 17class Text_Diff_Engine_shell {
 18
 19    /**
 20     * Path to the diff executable
 21     *
 22     * @var string
 23     */
 24    var $_diffCommand = 'diff';
 25
 26    /**
 27     * Returns the array of differences.
 28     *
 29     * @param array $from_lines lines of text from old file
 30     * @param array $to_lines   lines of text from new file
 31     *
 32     * @return array all changes made (array with Text_Diff_Op_* objects)
 33     */
 34    function diff($from_lines, $to_lines)
 35    {
 36        array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
 37        array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
 38
 39        $temp_dir = Text_Diff::_getTempDir();
 40
 41        // Execute gnu diff or similar to get a standard diff file.
 42        $from_file = tempnam($temp_dir, 'Text_Diff');
 43        $to_file = tempnam($temp_dir, 'Text_Diff');
 44        $fp = fopen($from_file, 'w');
 45        fwrite($fp, implode("\n", $from_lines));
 46        fclose($fp);
 47        $fp = fopen($to_file, 'w');
 48        fwrite($fp, implode("\n", $to_lines));
 49        fclose($fp);
 50        $diff = shell_exec($this->_diffCommand . ' ' . $from_file . ' ' . $to_file);
 51        unlink($from_file);
 52        unlink($to_file);
 53
 54        if (is_null($diff)) {
 55            // No changes were made
 56            return array(new Text_Diff_Op_copy($from_lines));
 57        }
 58
 59        $from_line_no = 1;
 60        $to_line_no = 1;
 61        $edits = array();
 62
 63        // Get changed lines by parsing something like:
 64        // 0a1,2
 65        // 1,2c4,6
 66        // 1,5d6
 67        preg_match_all('#^(\d+)(?:,(\d+))?([adc])(\d+)(?:,(\d+))?$#m', $diff,
 68            $matches, PREG_SET_ORDER);
 69
 70        foreach ($matches as $match) {
 71            if (!isset($match[5])) {
 72                // This paren is not set every time (see regex).
 73                $match[5] = false;
 74            }
 75
 76            if ($match[3] == 'a') {
 77                $from_line_no--;
 78            }
 79
 80            if ($match[3] == 'd') {
 81                $to_line_no--;
 82            }
 83
 84            if ($from_line_no < $match[1] || $to_line_no < $match[4]) {
 85                // copied lines
 86                assert($match[1] - $from_line_no == $match[4] - $to_line_no);
 87                array_push($edits,
 88                    new Text_Diff_Op_copy(
 89                        $this->_getLines($from_lines, $from_line_no, $match[1] - 1),
 90                        $this->_getLines($to_lines, $to_line_no, $match[4] - 1)));
 91            }
 92
 93            switch ($match[3]) {
 94            case 'd':
 95                // deleted lines
 96                array_push($edits,
 97                    new Text_Diff_Op_delete(
 98                        $this->_getLines($from_lines, $from_line_no, $match[2])));
 99                $to_line_no++;
100                break;
101
102            case 'c':
103                // changed lines
104                array_push($edits,
105                    new Text_Diff_Op_change(
106                        $this->_getLines($from_lines, $from_line_no, $match[2]),
107                        $this->_getLines($to_lines, $to_line_no, $match[5])));
108                break;
109
110            case 'a':
111                // added lines
112                array_push($edits,
113                    new Text_Diff_Op_add(
114                        $this->_getLines($to_lines, $to_line_no, $match[5])));
115                $from_line_no++;
116                break;
117            }
118        }
119
120        if (!empty($from_lines)) {
121            // Some lines might still be pending. Add them as copied
122            array_push($edits,
123                new Text_Diff_Op_copy(
124                    $this->_getLines($from_lines, $from_line_no,
125                                     $from_line_no + count($from_lines) - 1),
126                    $this->_getLines($to_lines, $to_line_no,
127                                     $to_line_no + count($to_lines) - 1)));
128        }
129
130        return $edits;
131    }
132
133    /**
134     * Get lines from either the old or new text
135     *
136     * @access private
137     *
138     * @param array $text_lines Either $from_lines or $to_lines (passed by reference).
139     * @param int   $line_no    Current line number (passed by reference).
140     * @param int   $end        Optional end line, when we want to chop more
141     *                          than one line.
142     *
143     * @return array The chopped lines
144     */
145    function _getLines(&$text_lines, &$line_no, $end = false)
146    {
147        if (!empty($end)) {
148            $lines = array();
149            // We can shift even more
150            while ($line_no <= $end) {
151                array_push($lines, array_shift($text_lines));
152                $line_no++;
153            }
154        } else {
155            $lines = array(array_shift($text_lines));
156            $line_no++;
157        }
158
159        return $lines;
160    }
161
162}
163