PHP 中的文本版本控制，具有差异突出显示

如果您曾经在 StackOverflow 上编辑过问题，您可能已经注意到它会跟踪问题所应用的确切更改。它以一种形式显示，突出显示文本中已删除的红色部分和自特定编辑以来添加的绿色部分。我的问题是如何自己实现这样一个系统。我正在尝试使用 PHP 和 MySQL 创建一个自定义 CMS，这似乎是一个非常酷的功能。

有什么建议，或者也许有开源库已经可以做到这一点，我可以分析他们是如何做到这一点的？

示范

在这里，我添加了一些文本，如果您单击编辑链接查看更改，这些文本将显示为绿色。

/*
    Paul's Simple Diff Algorithm v 0.1
    (C) Paul Butler 2007 <http://www.paulbutler.org/>
    May be used and distributed under the zlib/libpng license.

    This code is intended for learning purposes; it was written with short
    code taking priority over performance. It could be used in a practical
    application, but there are a few ways it could be optimized.

    Given two arrays, the function diff will return an array of the changes.
    I won't describe the format of the array, but it will be obvious
    if you use print_r() on the result of a diff on some test data.

    htmlDiff is a wrapper for the diff command, it takes two strings and
    returns the differences in HTML. The tags used are <ins> and <del>,
    which can easily be styled with CSS.
*/

function diff($old, $new){
    $maxlen = 0;
    foreach($old as $oindex => $ovalue){
        $nkeys = array_keys($new, $ovalue);
        foreach($nkeys as $nindex){
            $matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ?
                $matrix[$oindex - 1][$nindex - 1] + 1 : 1;
            if($matrix[$oindex][$nindex] > $maxlen){
                $maxlen = $matrix[$oindex][$nindex];
                $omax = $oindex + 1 - $maxlen;
                $nmax = $nindex + 1 - $maxlen;
            }
        }
    }
    if($maxlen == 0) return array(array('d'=>$old, 'i'=>$new));
    return array_merge(
        diff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
        array_slice($new, $nmax, $maxlen),
        diff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
}

function htmlDiff($old, $new){
    $ret = '';
    $diff = diff(explode(' ', $old), explode(' ', $new));
    foreach($diff as $k){
        if(is_array($k))
            $ret .= (!empty($k['d'])?'<del>'.implode(' ',$k['d']).'</del> ':'').
                (!empty($k['i'])?'<ins>'.implode(' ',$k['i']).'</ins> ':'');
        else $ret .= $k . ' ';
    }
    return $ret;
}

我很确定我改变了其中的某些内容。除此之外，它应该可以完美工作。

使用示例：

$a='abc defg h 12345';
$b='acb defg ikl 66 123 456';
echo htmlDiff($a,$b);

结果：

<del>abc</del> <ins>acb</ins> defg <del>h 12345</del> <ins>ikl 66 123 456</ins> 

并且明显地：

abc acb defg h 12345 ikl 66 123 456