Introduction of .editorfconfig and php-cs-fixer.

.editorconfig

@@ -0,0 +1,19 @@
+; top-most EditorConfig file
+root = true
+
+; Unix-style newlines
+[*]
+charset = utf-8
+end_of_line = LF
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{php,html,twig}]
+indent_style = space
+indent_size = 4
+
+[*.md]
+max_line_length = 80
+
+[COMMIT_EDITMSG]
+max_line_length = 0

.github/workflows/php.yml

@@ -26,5 +26,11 @@ jobs:
       - name: Composer install
         run: composer install --no-progress
 
+      - name: Run PHP-CS-Fixer
+        run: vendor/bin/php-cs-fixer fix -v --dry-run --stop-on-violation --using-cache=no
+
+      - name: Run PHPStan
+        run: vendor/bin/phpstan analyse --no-progress --error-format=github
+
       - name: Run PHPUnit
         run: vendor/bin/phpunit

.php-cs-fixer.dist.php

@@ -0,0 +1,38 @@
+<?php
+
+use PhpCsFixer\Config;
+use PhpCsFixer\Finder;
+use PhpCsFixer\Runner\Parallel\ParallelConfigFactory;
+
+if (!file_exists(__DIR__ . '/src') || !file_exists(__DIR__ . '/tests')) {
+    exit(0);
+}
+
+return (new Config())
+    // @see https://github.com/PHP-CS-Fixer/PHP-CS-Fixer/pull/7777
+    ->setParallelConfig(ParallelConfigFactory::detect())
+    ->setRules([
+        '@PHP71Migration' => true,
+        '@PHPUnit75Migration:risky' => true,
+        '@Symfony' => true,
+        '@Symfony:risky' => true,
+        'protected_to_private' => false,
+        'phpdoc_annotation_without_dot' => false,
+        'increment_style' => [
+            'style' => 'post',
+        ],
+        'phpdoc_types_order' => [
+            'null_adjustment' => 'always_first',
+        ],
+        'concat_space' => [
+            'spacing' => 'one',
+        ],
+    ])
+    ->setRiskyAllowed(true)
+    ->setFinder(
+        (new Finder())
+            ->in(__DIR__ . '/src')
+            ->in(__DIR__ . '/tests')
+            ->append([__FILE__])
+    )
+    ->setCacheFile('.php-cs-fixer.cache');

composer.json

@@ -14,14 +14,15 @@
         }
     ],
     "require": {
-        "php": ">=7.4",
+        "php": ">=8.1",
         "ext-json": "*"
     },
     "require-dev": {
         "phpunit/phpunit": "^11.5",
         "phpstan/phpstan": "^2.1",
         "phpstan/phpstan-phpunit": "^2.0",
-        "phpstan/extension-installer": "^1.4"
+        "phpstan/extension-installer": "^1.4",
+        "friendsofphp/php-cs-fixer": "^3.72"
     },
     "config": {
         "allow-plugins": {