Inital commit after splitting vom main project

src/CaseConverter.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tez\Utils\Str;
+
+final class CaseConverter
+{
+    /** Converts to camelCase. */
+    public static function toCamel(string $input): string
+    {
+        $words = self::words($input);
+
+        if ($words === []) {
+            return '';
+        }
+
+        return $words[0] . implode('', array_map('ucfirst', \array_slice($words, 1)));
+    }
+
+    /** Converts to PascalCase. */
+    public static function toPascal(string $input): string
+    {
+        return implode('', array_map('ucfirst', self::words($input)));
+    }
+
+    /** Converts to snake_case. */
+    public static function toSnake(string $input): string
+    {
+        return implode('_', self::words($input));
+    }
+
+    /** Converts to kebab-case. */
+    public static function toKebab(string $input): string
+    {
+        return implode('-', self::words($input));
+    }
+
+    /** Converts to SCREAMING_SNAKE_CASE. */
+    public static function toScreamingSnake(string $input): string
+    {
+        return mb_strtoupper(implode('_', self::words($input)));
+    }
+
+    /**
+     * Splits any supported format into lowercase words.
+     *
+     * Handles: camelCase, PascalCase, snake_case, kebab-case, SCREAMING_SNAKE_CASE.
+     *
+     * @return list<string>
+     */
+    private static function words(string $input): array
+    {
+        // Insert underscore before transitions from lowercase/digit to uppercase
+        $input = preg_replace('/([a-z\d])([A-Z])/', '$1_$2', $input) ?? $input;
+
+        // Insert underscore before transitions from a run of uppercase into mixed (e.g. HTMLParser → HTML_Parser)
+        $input = preg_replace('/([A-Z]+)([A-Z][a-z])/', '$1_$2', $input) ?? $input;
+
+        // Split on underscores, hyphens, and whitespace
+        $words = preg_split('/[_\-\s]+/', $input) ?: [];
+
+        return array_values(array_filter(
+            array_map('mb_strtolower', $words),
+            static fn(string $w): bool => $w !== '',
+        ));
+    }
+}