1 files changed, 51 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/attribute_set.rb b/activerecord/lib/active_record/attribute_set.rb
new file mode 100644
index 0000000000..102ef17e16
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_set.rb
@@ -0,0 +1,51 @@
+module ActiveRecord
+  class AttributeSet # :nodoc:
+    delegate :[], :[]=, :fetch, :include?, :keys, :each_with_object, to: :attributes
+
+    def initialize(attributes)
+      @attributes = attributes
+    end
+
+    def update(other)
+      attributes.update(other.attributes)
+    end
+
+    def freeze
+      @attributes.freeze
+      super
+    end
+
+    def initialize_dup(_)
+      @attributes = attributes.dup
+      attributes.each do |key, attr|
+        attributes[key] = attr.dup
+      end
+
+      super
+    end
+
+    def initialize_clone(_)
+      @attributes = attributes.clone
+      super
+    end
+
+    class Builder
+      def initialize(types)
+        @types = types
+      end
+
+      def build_from_database(values, additional_types = {})
+        attributes = values.each_with_object({}) do |(name, value), hash|
+          type = additional_types.fetch(name, @types[name])
+          hash[name] = Attribute.from_database(value, type)
+        end
+        AttributeSet.new(attributes)
+      end
+    end
+
+    protected
+
+    attr_reader :attributes
+
+  end
+end