<?php
/**
* Class used internally by Diff to actually compute the diffs.
*
* This class uses the Unix `diff` program via shell_exec to compute the
* differences between the two input arrays.
*
* Copyright 2007-2010 The Horde Project (http://www.horde.org/)
*
* See the enclosed file COPYING for license information (LGPL). If you did
* not receive this file, see http://opensource.org/licenses/lgpl-license.php.
*
* @author Milian Wolff <mail@milianw.de>
* @package Text_Diff
* @since 0.3.0
*/
class Text_Diff_Engine_shell {
/**
* Path to the diff executable
*
* @var string
*/
var $_diffCommand = 'diff';
/**
* Returns the array of differences.
*
* @param array $from_lines lines of text from old file
* @param array $to_lines lines of text from new file
*
* @return array all changes made (array with Text_Diff_Op_* objects)
*/
function diff($from_lines, $to_lines)
{
array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
$temp_dir = Text_Diff::_getTempDir();
// Execute gnu diff or similar to get a standard diff file.
$from_file = tempnam($temp_dir, 'Text_Diff');
$to_file = tempnam($temp_dir, 'Text_Diff');
$fp = fopen($from_file, 'w');
fwrite($fp, implode("\n", $from_lines));
fclose($fp);
$fp = fopen($to_file, 'w');
fwrite($fp, implode("\n", $to_lines));
fclose($fp);
$diff = shell_exec($this->_diffCommand . ' ' . $from_file . ' ' . $to_file);
unlink($from_file);
unlink($to_file);
if (is_null($diff)) {
// No changes were made
return array(new Text_Diff_Op_copy($from_lines));
}
$from_line_no = 1;
$to_line_no = 1;
$edits = array();
// Get changed lines by parsing something like:
// 0a1,2
// 1,2c4,6
// 1,5d6
preg_match_all('#^(\d+)(?:,(\d+))?([adc])(\d+)(?:,(\d+))?$#m', $diff,
$matches, PREG_SET_ORDER);
foreach ($matches as $match) {
if (!isset($match[5])) {
// This paren is not set every time (see regex).
$match[5] = false;
}
if ($match[3] == 'a') {
$from_line_no--;
}
if ($match[3] == 'd') {
$to_line_no--;
}
if ($from_line_no < $match[1] || $to_line_no < $match[4]) {
// copied lines
assert($match[1] - $from_line_no == $match[4] - $to_line_no);
array_push($edits,
new Text_Diff_Op_copy(
$this->_getLines($from_lines, $from_line_no, $match[1] - 1),
$this->_getLines($to_lines, $to_line_no, $match[4] - 1)));
}
switch ($match[3]) {
case 'd':
// deleted lines
array_push($edits,
new Text_Diff_Op_delete(
$this->_getLines($from_lines, $from_line_no, $match[2])));
$to_line_no++;
break;
case 'c':
// changed lines
array_push($edits,
new Text_Diff_Op_change(
$this->_getLines($from_lines, $from_line_no, $match[2]),
$this->_getLines($to_lines, $to_line_no, $match[5])));
break;
case 'a':
// added lines
array_push($edits,
new Text_Diff_Op_add(
$this->_getLines($to_lines, $to_line_no, $match[5])));
$from_line_no++;
break;
}
}
if (!empty($from_lines)) {
// Some lines might still be pending. Add them as copied
array_push($edits,
new Text_Diff_Op_copy(
$this->_getLines($from_lines, $from_line_no,
$from_line_no + count($from_lines) - 1),
$this->_getLines($to_lines, $to_line_no,
$to_line_no + count($to_lines) - 1)));
}
return $edits;
}
/**
* Get lines from either the old or new text
*
* @access private
*
* @param array $text_lines Either $from_lines or $to_lines (passed by reference).
* @param int $line_no Current line number (passed by reference).
* @param int $end Optional end line, when we want to chop more
* than one line.
*
* @return array The chopped lines
*/
function _getLines(&$text_lines, &$line_no, $end = false)
{
if (!empty($end)) {
$lines = array();
// We can shift even more
while ($line_no <= $end) {
array_push($lines, array_shift($text_lines));
$line_no++;
}
} else {
$lines = array(array_shift($text_lines));
$line_no++;
}
return $lines;
}
}