Added PhpCsFixer rule for variable names using camelCase.

Author: dragonwize

.gitignore

@@ -0,0 +1,2 @@
+/vendor/
+composer.lock

composer.json

@@ -0,0 +1,32 @@
+{
+    "name": "dragonwize/php-code-quality",
+    "description": "Opinionated PHP code quality config.",
+    "type": "library",
+    "require": {
+        "php": ">=8.5"
+    },
+    "require-dev": {
+        "friendsofphp/php-cs-fixer": "^3.94",
+        "phpstan/phpstan": "^2.1",
+        "phpstan/extension-installer": "^1.4",
+        "phpunit/phpunit": "^13.0"
+    },
+    "license": "MIT",
+    "autoload": {
+        "psr-4": {
+            "Dragonwize\\PhpCodeQuality\\": "src/"
+        }
+    },
+    "authors": [
+        {
+            "name": "dragonwize",
+            "email": "dragonwize@gmail.com"
+        }
+    ],
+    "minimum-stability": "stable",
+    "config": {
+        "allow-plugins": {
+            "phpstan/extension-installer": true
+        }
+    }
+}

src/PhpCsFixer/Rule/VariableNameCaseFixer.php

@@ -0,0 +1,99 @@
+<?php 
+
+declare(strict_types=1);
+
+namespace Dragonwize\PhpCodeQuality\PhpCsFixer\Rule;
+
+use PhpCsFixer\Fixer\FixerInterface;
+use PhpCsFixer\FixerDefinition\CodeSample;
+use PhpCsFixer\FixerDefinition\FixerDefinition;
+use PhpCsFixer\FixerDefinition\FixerDefinitionInterface;
+use PhpCsFixer\Tokenizer\Token;
+use PhpCsFixer\Tokenizer\Tokens;
+
+final class VariableNameCaseFixer implements FixerInterface
+{
+    public function getName(): string
+    {
+        return 'Dragonwize/variable_name_case';
+    }
+
+    public function getDefinition(): FixerDefinitionInterface
+    {
+        return new FixerDefinition(
+            'Enforce camelCase for variable names.',
+            [
+                new CodeSample("<?php \$my_variable = 2;\n"),
+            ],
+            'Make sure to run a static analyzer after changes.',
+        );
+    }
+
+    public function isCandidate(Tokens $tokens): bool
+    {
+        return $tokens->isAnyTokenKindsFound([\T_VARIABLE, \T_STRING_VARNAME]);
+    }
+
+    public function isRisky(): bool
+    {
+        return true;
+    }
+
+    public function fix(\SplFileInfo $file, Tokens $tokens): void
+    {
+        if ($tokens->count() > 0 && $this->isCandidate($tokens) && $this->supports($file)) {
+            $this->applyFix($file, $tokens);
+        }
+    }
+
+    public function getPriority(): int
+    {
+        return 0;
+    }
+
+    public function supports(\SplFileInfo $file): bool
+    {
+        return true;
+    }
+
+    private function applyFix(\SplFileInfo $file, Tokens $tokens): void
+    {
+        foreach ($tokens as $index => $token) {
+            if (!$token->isGivenKind([\T_VARIABLE, \T_STRING_VARNAME, \T_PROPERTY_C])) {
+                continue;
+            }
+
+            $content = $token->getContent();
+
+            // Skip $this and superglobals
+            if ($this->shouldSkip($content)) {
+                continue;
+            }
+
+            $newName = $this->toCamelCase($content);
+
+            if ($content !== $newName) {
+                $tokens[$index] = new Token([$token->getId(), $newName]);
+            }
+        }
+    }
+
+    private function shouldSkip(string $name): bool
+    {
+        // Skip specific variable names.
+        if ($name === '$this') {
+            return true;
+        }
+
+        if (\array_key_exists(ltrim($name, '$'), $GLOBALS)) {
+            return true;
+        }
+
+        return false;
+    }
+
+    private function toCamelCase(string $variableName): string
+    {
+        return str_replace('_', '', ucwords(trim($variableName), '_ '));
+    }
+}