Add MiniRacer::Platform.set_flags! for the truffleruby backend

lib/mini_racer/truffleruby.rb

@@ -331,10 +331,37 @@ def idle_notification(idle_time)
   end
 
   class Platform
-    def self.set_flag_as_str!(flag)
-      raise TypeError, "wrong type argument #{flag.class} (should be a string)" unless flag.is_a?(String)
-      raise MiniRacer::PlatformAlreadyInitialized, "The platform is already initialized." if Context.instance_variable_get(:@context_initialized)
-      Context.instance_variable_set(:@use_strict, true) if "--use_strict" == flag
+    class << self
+      def set_flags!(*args, **kwargs)
+        flags_to_strings([args, kwargs]).each do |flag|
+          set_flag_as_str!(flag)
+        end
+      end
+
+    private
+
+      def flags_to_strings(flags)
+        flags.flatten.map { |flag| flag_to_string(flag) }.flatten
+      end
+
+      # normalize flags to strings, and adds leading dashes if needed
+      def flag_to_string(flag)
+        if flag.is_a?(Hash)
+          flag.map do |key, value|
+            "#{flag_to_string(key)} #{value}"
+          end
+        else
+          str = flag.to_s
+          str = "--#{str}" unless str.start_with?('--')
+          str
+        end
+      end
+
+      def set_flag_as_str!(flag)
+        raise TypeError, "wrong type argument #{flag.class} (should be a string)" unless flag.is_a?(String)
+        raise MiniRacer::PlatformAlreadyInitialized, "The platform is already initialized." if Context.instance_variable_get(:@context_initialized)
+        Context.instance_variable_set(:@use_strict, true) if "--use_strict" == flag
+      end
     end
   end