philiprehberger/php-diff

Diff strings, arrays, and objects with unified, HTML, and structured output

v1.2.0 2026-03-28 00:57 UTC

Requires

• php: ^8.2

Requires (Dev)

• laravel/pint: ^1.0
• phpstan/phpstan: ^1.12|^2.0
• phpunit/phpunit: ^11.0

MIT

• Philip Rehberger

• php
• diff
• compare
• unified-diff
• myers
• html-diff

README

Diff strings, arrays, and objects with unified, HTML, and structured output.

Requirements

• PHP 8.2+

Installation

composer require philiprehberger/php-diff

Usage

Comparing Strings

use PhilipRehberger\Diff\Diff;

$diff = Diff::strings("hello\nworld", "hello\nphp");

$diff->hasChanges();         // true
$diff->toUnified();          // unified diff string
$diff->toHtml();             // HTML with <ins>/<del> tags
$diff->toHtmlSideBySide();   // side-by-side HTML table
$diff->toAnsi();             // ANSI-colored terminal output
$diff->toArray();            // array of DiffLine objects
$diff->stats();              // DiffStats { added: 1, removed: 1, unchanged: 1 }
$diff->similarity();         // 0.333... (0.0 = completely different, 1.0 = identical)

Ignore Options

use PhilipRehberger\Diff\Diff;

// Normalize whitespace before comparing
$diff = Diff::strings("hello  world", "hello world")->ignoreWhitespace();
$diff->hasChanges(); // false

// Case-insensitive comparison
$diff = Diff::strings("Hello", "hello")->ignoreCase();
$diff->hasChanges(); // false

// Ignore blank lines
$diff = Diff::strings("hello\n\nworld", "hello\nworld")->ignoreBlankLines();
$diff->hasChanges(); // false

Context Lines

use PhilipRehberger\Diff\Diff;

$diff = Diff::strings($oldText, $newText);

$diff->toUnified(1);   // 1 line of context around changes
$diff->toUnified(5);   // 5 lines of context around changes

Similarity Score

use PhilipRehberger\Diff\Diff;

$diff = Diff::strings("hello\nworld", "hello\nphp");

$diff->similarity(); // 0.333... - one of three lines is unchanged

Side-by-Side HTML

use PhilipRehberger\Diff\Diff;

$diff = Diff::strings("hello\nworld", "hello\nphp");

$html = $diff->toHtmlSideBySide();
// <table class="diff-table">
//   <tr><td class="diff-left diff-unchanged">hello</td><td class="diff-right diff-unchanged">hello</td></tr>
//   <tr><td class="diff-left diff-removed">world</td><td class="diff-right"></td></tr>
//   <tr><td class="diff-left"></td><td class="diff-right diff-added">php</td></tr>
// </table>

Comparing Arrays

use PhilipRehberger\Diff\Diff;

$diff = Diff::arrays(
    ['name' => 'Alice', 'age' => 30, 'city' => 'NYC'],
    ['name' => 'Alice', 'age' => 31, 'country' => 'US'],
);

$diff->hasChanges();  // true
$diff->changes();     // all Change objects
$diff->added();       // entries only in the new array
$diff->removed();     // entries only in the old array
$diff->changed();     // entries with different values

Comparing Objects

use PhilipRehberger\Diff\Diff;

$old = (object) ['name' => 'Alice', 'age' => 30];
$new = (object) ['name' => 'Alice', 'age' => 31];

$diff = Diff::objects($old, $new);

$diff->hasChanges();  // true
$diff->changes();     // [PropertyChange { property: 'age', from: 30, to: 31 }]

API

Diff (Static Entry Point)

Method	Returns	Description
Diff::strings(string $old, string $new)	StringDiff	Compare two strings line by line
Diff::arrays(array $old, array $new)	ArrayDiff	Compare two arrays by key
Diff::objects(object $old, object $new)	ObjectDiff	Compare two objects by property

StringDiff

Method	Returns	Description
ignoreWhitespace()	StringDiff	Normalize whitespace before comparing
ignoreCase()	StringDiff	Lowercase both inputs before comparing
ignoreBlankLines()	StringDiff	Remove blank lines before comparing
toUnified(int $context = 3)	string	Unified diff format
toAnsi(int $context = 3)	string	ANSI-colored unified diff for terminals
toHtml()	string	HTML with ins/del tags
toHtmlSideBySide()	string	Side-by-side HTML table
toArray()	array<DiffLine>	Array of DiffLine value objects
hasChanges()	bool	Whether any differences exist
stats()	DiffStats	Count of added, removed, unchanged lines
similarity()	float	Ratio of unchanged to total lines (0.0-1.0)

ArrayDiff

Method	Returns	Description
changes()	array<Change>	All changes
added()	array<Change>	Only added entries
removed()	array<Change>	Only removed entries
changed()	array<Change>	Only modified entries
hasChanges()	bool	Whether any differences exist

ObjectDiff

Method	Returns	Description
changes()	array<PropertyChange>	All property changes
hasChanges()	bool	Whether any differences exist

Value Objects

• DiffLine - type (added|removed|unchanged), content, lineNumber
• Change - key, old, new, type (added|removed|changed)
• PropertyChange - property, from, to
• DiffStats - added, removed, unchanged

Development

composer install
vendor/bin/phpunit
vendor/bin/pint --test

Support

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License

MIT