DIFF string comparison for PHP

Class used to compare differences between two strings using a DIFF implementation, with the possibility to render the diff to HTML with highlighting.

Requirements

• PHP 7.4+
• Composer

Installation

Require via composer:

require mistralys/text-diff

Or clone it locally via GIT, or download any of the available releases.

Usage

Comparing strings

use Mistralys\Diff\Diff;

$diff = Diff::compareStrings('String 1', 'String 2');

Comparing files

use Mistralys\Diff\Diff;

$diff = Diff::compareFiles('/path/to/file1', '/path/to/file2');

Once the diff instance has been created, choose any of the toXXX methods to retrieve the diff in your preferred format.

use Mistralys\Diff\Diff;

$diff = Diff::compareFiles('/path/to/file1', '/path/to/file2');

$string = $diff->toString();
$html = $diff->toHTML();
$table = $diff->toHTMLTable();
$array = $diff->toArray();

Changing the comparison mode

By default, the comparison will be made per line. It can be changed to be done on a per-character basis:

use Mistralys\Diff\Diff;

$diff = Diff::compareFiles('/path/to/file1', '/path/to/file2');

$diff->setCompareCharacters(true);

HTML Highlighting

The toHTML and toHTMLTable methods support highlighting the changes with the integrated CSS styles. To insert these, use the Styler class: it offers several ways to access the CSS.

use Mistralys\Diff\Diff;

$diff = Diff::compareFiles('/path/to/file1', '/path/to/file2');
$styler = Diff::createStyler();

From here, use any of the styler's methods according to your project's needs.

use Mistralys\Diff\Diff;

$styler = Diff::createStyler();

$css = $styler->getCSS(); // get the raw CSS styles
$tag = $styler->getStyleTag(); // CSS styles with a <style> tag
$path = $styler->getStylesheetPath(); // absolute path to the file
$url = $styler->getStylesheetURL('/vendor'); // URL to the file, given the vendor folder URL

For example, to show a highlighted diff with inline styles:

use Mistralys\Diff\Diff;

$diff = Diff::compareStrings('String 1', 'String 2');

echo Diff::createStyler()->getStyleTag();
echo $diff->toHTML();

Credits

The original Diff class was developed by Kate Morley. Compared to her version, this has been reworked extensively. The core mechanism stays the same, but updated for PHP7, and split up into subclasses to make it easier to extend and maintain. The static comparison methods are still there, but they return a diff instance now.

The original project homepage can be found here:

http://code.iamkate.com/php/diff-implementation/

Kate has since removed the library from her site, but I am keeping this here as reference.