added a tokenizer for outward and inward splitting of postcode

src/Utils/Tokenizer.php

@@ -0,0 +1,34 @@
+<?php
+namespace RapidWeb\Postcodes\Utils;
+
+use RapidWeb\Postcodes\Utils\Validator;
+use Exception;
+
+abstract class Tokenizer
+{
+    public static function outward($postcode)
+    {
+     self::sanityCheck($postcode);
+
+     $postcodeStart = trim(substr($postcode, 0, -3));
+
+     return $postcodeStart;
+    }
+
+    public static function inward($postcode)
+    {
+      self::sanityCheck($postcode);
+
+      $postcodeEnd = trim(substr($postcode, -3,3));
+
+      return $postcodeEnd;
+    }
+
+    private function sanityCheck($postcode)
+    {
+        $validated = Validator::validatePostcode($postcode);
+
+        throw new Exception("Post code provided is not valid");
+    }
+
+}