PHP implementation of a Fine granularity Diff engine

1.0.2 2022-05-23 07:44 UTC

This package is auto-updated.

Last update: 2022-06-23 08:04:34 UTC




FineDiff is a rather simple library to create HTML diff view of two strings:

echo (new Diff())->render('hello world', 'hello2 worlds');
hello<ins>2</ins> world<ins>s</ins>


$ composer req lolli42/finediff


  • 1.x Dropped PHP <7.2, has PHP >=7.2 support, added multibyte support, forces strict types, E_ALL error free
  • <1.x is identical to cogpowered/finediff from (


Render the difference between two strings as HTML on a character basis:

echo (new Diff())->render('string one', 'string two');
string <ins>tw</ins>o<del>ne</del>

Render the difference between two strings as HTML on a word basis:

echo (new Diff(new Word()))->render('string one', 'string two');
string <del>one</del><ins>two</ins>

Special characters and entities are quoted by HTML renderer and multibyte strings are handled:

echo (new Diff())->render('foo<bär>baz', 'foo<qüx>baz');


To create a diff-view between two string, an intermediate "Opcode" representation is created that specifies the differences form string one to string two. The renderer then takes this opcode and creates HTML from it. Note the opcode string is considered internal and may change in a backwards breaking way with younger library releases.

$diff = new Diff();
echo $diff->getOpcodes('hello world', 'hello2 worlds');
// c5i:2c6i:s
// Means: copy 5 chars "hello", then insert "2", then copy 6 chars " world", then insert "s"
echo $diff->process('hello wordl', 'c5i:2c6i:s');
// hello<ins>2</ins> world<ins>s</ins>

Running tests

Full test run:

$ composer update
$ vendor/bin/phpunit

Restricting to single files:

$ composer update
$ vendor/bin/phpunit tests/DiffTest.php

Casual setup to run tests with xdebug (3.x) enabled, an IDE like phpstorm should then break point:

$ composer update
$ XDEBUG_MODE="debug,develop" XDEBUG_TRIGGER="foo" vendor/bin/phpunit



MIT License. See LICENSE file.