add Hash#to_h; ref #2348

mrbgems/mruby-hash-ext/mrblib/hash.rb

@@ -182,4 +182,15 @@ class Hash
     end
     nil
   end
+
+  ##
+  #  call-seq:
+  #     hsh.to_h     -> hsh or new_hash
+  #
+  #  Returns +self+. If called on a subclass of Hash, converts
+  #  the receiver to a Hash object.
+  #
+  def to_h
+    self
+  end
 end

mrbgems/mruby-hash-ext/test/hash.rb

@@ -115,3 +115,9 @@ assert("Hash#key") do
   assert_nil h.key('nil')
   assert_equal 'nil', h.key(nil)
 end
+
+assert("Hash#to_h") do
+  h = { "a" => 100, "b" => 200 }
+  assert_equal Hash, h.to_h.class
+  assert_equal h, h.to_h
+end