1 files changed, 40 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/attribute_set/yaml_encoder.rb b/activemodel/lib/active_model/attribute_set/yaml_encoder.rb
new file mode 100644
index 0000000000..ea1efc160e
--- /dev/null
+++ b/activemodel/lib/active_model/attribute_set/yaml_encoder.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module ActiveModel
+  class AttributeSet
+    # Attempts to do more intelligent YAML dumping of an
+    # ActiveModel::AttributeSet to reduce the size of the resulting string
+    class YAMLEncoder # :nodoc:
+      def initialize(default_types)
+        @default_types = default_types
+      end
+
+      def encode(attribute_set, coder)
+        coder["concise_attributes"] = attribute_set.each_value.map do |attr|
+          if attr.type.equal?(default_types[attr.name])
+            attr.with_type(nil)
+          else
+            attr
+          end
+        end
+      end
+
+      def decode(coder)
+        if coder["attributes"]
+          coder["attributes"]
+        else
+          attributes_hash = Hash[coder["concise_attributes"].map do |attr|
+            if attr.type.nil?
+              attr = attr.with_type(default_types[attr.name])
+            end
+            [attr.name, attr]
+          end]
+          AttributeSet.new(attributes_hash)
+        end
+      end
+
+      private
+        attr_reader :default_types
+    end
+  end
+end