PHP/JS Text Diff

Question

First off, this is an exact duplicate of these four questions:

• Highlight the difference between two strings in PHP
• JavaScript based diff utility
• How to do text DIFF using PHP?
• Calculate text diffs in PHP

It seems as though times have changed since these questions were first asked and I am wondering what is a good tool now-a-days for this sort of comparison? I have looked at (additionally to those questions):

• https://github.com/nuxodin/diff_match_patch-php
• http://pear.php.net/package/Text_Diff
• https://github.com/paulgb/simplediff/blob/5bfe1d2a8f967c7901ace50f04ac2d9308ed3169/simplediff.php
• http://www.raymondhill.net/finediff/viewdiff-ex.php

But all of the ones I get are either unmantained now or seem a little dodgy in that they are not used that much (and some even hint that they are not very performant) and the PEAR one worries me. I hate to install PEAR for one little module not only that but it seems like throwing a brick through my own window to install it for such a small module in comparison to PEAR in general not only that but the module has been superseded and placed on a different channel (dunno why?). I would use the PEAR version if it is my only choice but I want to use the upto date package.

Does anyone know of a well used and currently maintained or built in function (even if it is a PHP extension) text diff for PHP and/or JavaScript (JQuery as well)?

Answer 1

Ok so it has been a while.

I actually decided to look around at what other people use and stumbled upon what Yii ( http://www.yiiframework.com ) uses.

They actually use the PEAR module for their text_diff and they use it in its new form on the horde channel. It seems that text_diff is now a horde project but you can just as easily integrate a version of it into your application and that is what Yii does by default (it comes pre-bundled with a version of it).

So I searched around a bit to find out how they used it and how to get into it and I came across:

public function actionDiff()
{
    Yii::import('gii.components.TextDiff');

    $model=$this->prepare();
    if(isset($_GET['id']) && isset($model->files[$_GET['id']]))
    {
        $file=$model->files[$_GET['id']];
        if(!in_array($file->type,array('php', 'txt','js','css')))
            $diff=false;
        elseif($file->operation===CCodeFile::OP_OVERWRITE)
            $diff=TextDiff::compare(file_get_contents($file->path), $file->content);
        else
            $diff='';

        $this->renderPartial('/common/diff',array(
            'file'=>$file,
            'diff'=>$diff,
        ));
    }
    else
        throw new CHttpException(404,'Unable to find the code you requested.');
}

In CCodeGenerator for their Gii module ( http://www.yiiframework.com/doc/api/1.1/CCodeGenerator/ ). The important part is where they actually hook into the PEAR module:

$diff=TextDiff::compare(file_get_contents($file->path), $file->content);

By reading in the contents of two files which produces a diffed output.

Originally I did not want to use PEAR because of the bloat but this module is quite slim for a fully featured text_diff so I have decided to go with this. Not only that but, at the moment, it is the only text_diff module that has truly worked for me so I am keeping with the best, even if the best is quite memory hungry.

Answer 2

Have you tried one of Philippe's two solutions on this thread?

Quoted here:

In PHP. array_diff compares the first against the second array and returns the difference.

$a1 = str_split('abcdefghijklmnop');
$a2 = str_split('abcdefghi');
echo join('', array_diff($a1, $a2)); // jklmnop

This will work as well:

$s1 = 'abcdefghijklmnop';
$s2 = 'abcdefghi';
echo str_replace(str_split($s2), '', $s1); // jklmnop

This could handle $s2 = 'ghiabcdef'; as well because str_replace() is fed with an array, not a string.