Move common DateTime calculations to Date. Closes #8536.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6921 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 108 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/date/calculations.rb b/activesupport/lib/active_support/core_ext/date/calculations.rb
index c522256aea..de354540e9 100644
--- a/activesupport/lib/active_support/core_ext/date/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date/calculations.rb
@@ -52,6 +52,114 @@ module ActiveSupport #:nodoc:
               options[:day]   || options[:mday] || self.day # mday is deprecated
             )
           end
+          
+          # Returns a new Date/DateTime representing the time a number of specified months ago
+          def months_ago(months)
+            months_since(-months)
+          end
+
+          def months_since(months)
+            year, month, day = self.year, self.month, self.day
+
+            month += months
+
+            # in case months is negative
+            while month < 1
+             month += 12
+             year -= 1
+            end
+
+            # in case months is positive
+            while month > 12
+             month -= 12
+             year += 1
+            end
+
+            max = ::Time.days_in_month(month, year)
+            day = max if day > max
+
+            change(:year => year, :month => month, :day => day)
+          end
+
+          # Returns a new Date/DateTime representing the time a number of specified years ago
+          def years_ago(years)
+            change(:year => self.year - years)
+          end
+
+          def years_since(years)
+            change(:year => self.year + years)
+          end
+
+          # Short-hand for years_ago(1)
+          def last_year
+            years_ago(1)
+          end
+
+          # Short-hand for years_since(1)
+          def next_year
+            years_since(1)
+          end
+
+          # Short-hand for months_ago(1)
+          def last_month
+            months_ago(1)
+          end
+
+          # Short-hand for months_since(1)
+          def next_month
+            months_since(1)
+          end
+
+          # Returns a new Date/DateTime representing the "start" of this week (i.e, Monday; DateTime objects will have time set to 0:00)
+          def beginning_of_week
+            days_to_monday = self.wday!=0 ? self.wday-1 : 6
+            result = self - days_to_monday
+            self.acts_like?(:time) ? result.midnight : result
+          end
+          alias :monday :beginning_of_week
+          alias :at_beginning_of_week :beginning_of_week
+
+          # Returns a new Date/DateTime representing the start of the given day in next week (default is Monday).
+          def next_week(day = :monday)
+            days_into_week = { :monday => 0, :tuesday => 1, :wednesday => 2, :thursday => 3, :friday => 4, :saturday => 5, :sunday => 6}
+            result = (self + 7).beginning_of_week + days_into_week[day]
+            self.acts_like?(:time) ? result.change(:hour => 0) : result
+          end          
+
+          # Returns a new ; DateTime objects will have time set to 0:00DateTime representing the start of the month (1st of the month; DateTime objects will have time set to 0:00)
+          def beginning_of_month
+            self.acts_like?(:time) ? change(:day => 1,:hour => 0, :min => 0, :sec => 0) : change(:day => 1)
+          end
+          alias :at_beginning_of_month :beginning_of_month
+
+          # Returns a new Date/DateTime representing the end of the month (last day of the month; DateTime objects will have time set to 0:00)
+          def end_of_month
+            last_day = ::Time.days_in_month( self.month, self.year )
+            self.acts_like?(:time) ? change(:day => last_day,:hour => 0, :min => 0, :sec => 0) : change(:day => last_day)
+          end
+          alias :at_end_of_month :end_of_month
+
+          # Returns a new Date/DateTime representing the start of the quarter (1st of january, april, july, october; DateTime objects will have time set to 0:00)
+          def beginning_of_quarter
+            beginning_of_month.change(:month => [10, 7, 4, 1].detect { |m| m <= self.month })
+          end
+          alias :at_beginning_of_quarter :beginning_of_quarter
+
+          # Returns a new Date/DateTime representing the start of the year (1st of january; DateTime objects will have time set to 0:00)
+          def beginning_of_year
+            self.acts_like?(:time) ? change(:month => 1, :day => 1, :hour => 0, :min => 0, :sec => 0) : change(:month => 1, :day => 1)
+          end
+          alias :at_beginning_of_year :beginning_of_year
+
+          # Convenience method which returns a new Date/DateTime representing the time 1 day ago
+          def yesterday
+            self - 1
+          end
+
+          # Convenience method which returns a new Date/DateTime representing the time 1 day since the instance time
+          def tomorrow
+            self + 1
+          end
         end
       end
     end