Add state to expect object keys

src/State.php

@@ -29,6 +29,13 @@ class State
      */
     public string $buffer = '';
 
+    /**
+     * Whether the token should be an object key.
+     *
+     * @var bool
+     */
+    public bool $expectsKey = false;
+
     /**
      * Instantiate the class.
      *