Adding scheme validator

Author: nyamsprod

UriString.php

@@ -730,6 +730,25 @@ private static function filterHost(Stringable|string|null $host): ?string
         throw new SyntaxError(sprintf('Host `%s` is invalid : the IP host is malformed', $host));
     }
 
+    /**
+     * Tells whether the scheme component is valid
+     *
+     * @param Stringable|string|null $scheme
+     *
+     * @return bool
+     */
+    public static function isScheme(Stringable|string|null $scheme): bool
+    {
+        return null === $scheme || 1 === preg_match('/^[A-Za-z]([-A-Za-z\d+.]+)?$/', (string) $scheme);
+    }
+
+    /**
+     * Tells whether the host component is valid
+     *
+     * @param Stringable|string|null $host
+     *
+     * @return bool
+     */
     public static function isHost(Stringable|string|null $host): bool
     {
         try {