1 files changed, 19 insertions, 14 deletions

diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 6ec0c3a70a..c9e8c8fdc4 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -7,22 +7,30 @@ module ActiveSupport
   #
   #   1.month.ago       # equivalent to Time.now.advance(months: -1)
   class Duration
+    EPOCH = ::Time.utc(2000)
+
     attr_accessor :value, :parts
 
     autoload :ISO8601Parser,     "active_support/duration/iso8601_parser"
     autoload :ISO8601Serializer, "active_support/duration/iso8601_serializer"
 
     def initialize(value, parts) #:nodoc:
-      @value, @parts = value, parts
+      @value, @parts = value, parts.to_h
+      @parts.default = 0
     end
 
     # Adds another Duration or a Numeric to this Duration. Numeric values
     # are treated as seconds.
     def +(other)
       if Duration === other
-        Duration.new(value + other.value, @parts + other.parts)
+        parts = @parts.dup
+        other.parts.each do |(key, value)|
+          parts[key] += value
+        end
+        Duration.new(value + other.value, parts)
       else
-        Duration.new(value + other, @parts + [[:seconds, other]])
+        seconds = @parts[:seconds] + other
+        Duration.new(value + other, @parts.merge(seconds: seconds))
       end
     end
 
@@ -33,7 +41,7 @@ module ActiveSupport
     end
 
     def -@ #:nodoc:
-      Duration.new(-value, parts.map { |type,number| [type, -number] })
+      Duration.new(-value, parts.map { |type, number| [type, -number] })
     end
 
     def is_a?(klass) #:nodoc:
@@ -119,7 +127,7 @@ module ActiveSupport
 
     def inspect #:nodoc:
       parts.
-        reduce(::Hash.new(0)) { |h,(l,r)| h[l] += r; h }.
+        reduce(::Hash.new(0)) { |h, (l, r)| h[l] += r; h }.
         sort_by { |unit,  _ | [:years, :months, :weeks, :days, :hours, :minutes, :seconds].index(unit) }.
         map     { |unit, val| "#{val} #{val == 1 ? unit.to_s.chop : unit.to_s}" }.
         to_sentence(locale: ::I18n.default_locale)
@@ -129,7 +137,7 @@ module ActiveSupport
       to_i
     end
 
-    def respond_to_missing?(method, include_private=false) #:nodoc:
+    def respond_to_missing?(method, include_private = false) #:nodoc:
       @value.respond_to?(method, include_private)
     end
 
@@ -140,8 +148,7 @@ module ActiveSupport
     # If invalid string is provided, it will raise +ActiveSupport::Duration::ISO8601Parser::ParsingError+.
     def self.parse(iso8601duration)
       parts = ISO8601Parser.new(iso8601duration).parse!
-      time  = ::Time.current
-      new(time.advance(parts) - time, parts)
+      new(EPOCH.advance(parts) - EPOCH, parts)
     end
 
     # Build ISO 8601 Duration string for this duration.
@@ -152,10 +159,10 @@ module ActiveSupport
 
     delegate :<=>, to: :value
 
-    protected
+    private
 
-      def sum(sign, time = ::Time.current) #:nodoc:
-        parts.inject(time) do |t,(type,number)|
+      def sum(sign, time = ::Time.current)
+        parts.inject(time) do |t, (type, number)|
           if t.acts_like?(:time) || t.acts_like?(:date)
             if type == :seconds
               t.since(sign * number)
@@ -172,9 +179,7 @@ module ActiveSupport
         end
       end
 
-    private
-
-      def method_missing(method, *args, &block) #:nodoc:
+      def method_missing(method, *args, &block)
         value.send(method, *args, &block)
       end
   end