A native PHP library for generating word-level diffs of plain text, inspired by the JavaScript pandiff tool. This library focuses on providing a reusable, AST-like comparison of text streams (tokenized by words) without external binary dependencies like Pandoc.

• Word-level Diffing: Accurately highlights additions and deletions at the word level, detecting changes within sentences rather than just line-by-line.
• Native PHP: Built on top of sebastian/diff, requiring no non-PHP binaries or external command-line tools.
• Customizable Output: Returns a string with {--deleted--} and {++added++} markers, which can be easily parsed or replaced with HTML tags or other formats.
• Puncutation Aware: Tokenizer respects punctuation and whitespace, ensuring clean diffs.

Install via Composer:

composer require writepath/pandiff-php

Use the DiffEngine to compare two strings.

use Pandiff\DiffEngine;

$engine = new DiffEngine();

$old = "The quick brown fox.";
$new = "The fast brown fox.";

$result = $engine->diff($old, $new);

echo $result;
// Output: The {--quick--}{++fast++} brown fox.

The default output uses a custom format {--...--} for deletions and {++...++} for additions. You can easily process this into HTML using regular expressions.

use Pandiff\DiffEngine;

$engine = new DiffEngine();

$old = "This is a simple test.";
$new = "This is a complex test.";

$diff = $engine->diff($old, $new);

// Convert to HTML
$html = preg_replace(
    ['/\{\+\+(.*?)\+\+\}/', '/\{\-\-(.*?)\-\-\}/'],
    ['<ins>$1</ins>', '<del>$1</del>'],
    $diff
);

echo $html;
// Output: This is a <del>simple</del><ins>complex</ins> test.

1. Tokenization: The input text is split into a stream of tokens (words, whitespace, punctuation) using a Unicode-aware regex.
2. LCS Calculation: The library uses a Longest Common Subsequence algorithm (via sebastian/diff) to find the differences between the token streams.
3. Reconstruction: The result is reconstructed into a string with markup indicating the changes.

Run the test suite with PHPUnit:

vendor/bin/phpunit

MIT