1 files changed, 23 insertions, 1 deletions
diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index c63b61e97a..3bde541009 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -9,6 +9,9 @@ module ActiveSupport
   class Duration
     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
     end
@@ -117,7 +120,7 @@ module ActiveSupport
     def inspect #:nodoc:
       parts.
         reduce(::Hash.new(0)) { |h,(l,r)| h[l] += r; h }.
-        sort_by {|unit,  _ | [:years, :months, :days, :minutes, :seconds].index(unit)}.
+        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)
     end
@@ -130,6 +133,23 @@ module ActiveSupport
       @value.respond_to?(method, include_private)
     end
 
+    # Creates a new Duration from string formatted according to ISO 8601 Duration.
+    #
+    # See {ISO 8601}[http://en.wikipedia.org/wiki/ISO_8601#Durations] for more information.
+    # This method allows negative parts to be present in pattern.
+    # 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)
+    end
+
+    # Build ISO 8601 Duration string for this duration.
+    # The +precision+ parameter can be used to limit seconds' precision of duration.
+    def iso8601(precision: nil)
+      ISO8601Serializer.new(self, precision: precision).serialize
+    end
+
     delegate :<=>, to: :value
 
     protected
@@ -139,6 +159,8 @@ module ActiveSupport
           if t.acts_like?(:time) || t.acts_like?(:date)
             if type == :seconds
               t.since(sign * number)
+            elsif [:hours, :minutes].include?(type)
+              t.in_time_zone.advance(type => sign * number)
             else
               t.advance(type => sign * number)
             end