7 files changed, 82 insertions, 0 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 804336da91..00fcfe2001 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Add `Time#prev_quarter' and 'Time#next_quarter' short-hands for months_ago(3) and months_since(3). *SungHee Kang*
+
 *   Remove obsolete and unused `require_association` method from dependencies. *fxn*
 
 *   Add `:instance_accessor` option for `config_accessor`.
diff --git a/activesupport/lib/active_support/core_ext/date/calculations.rb b/activesupport/lib/active_support/core_ext/date/calculations.rb
index 8a7eb6bc6b..7fe4161fb4 100644
--- a/activesupport/lib/active_support/core_ext/date/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date/calculations.rb
@@ -202,6 +202,17 @@ class Date
     acts_like?(:time) ? result.change(:hour => 0) : result
   end
 
+  # Short-hand for months_ago(3)
+  def prev_quarter
+    months_ago(3)
+  end
+  alias_method :last_quarter, :prev_quarter
+
+  # Short-hand for months_since(3)
+  def next_quarter
+    months_since(3)
+  end
+
   # Returns a new Date/DateTime representing the start of the month (1st of the month; DateTime objects will have time set to 0:00)
   def beginning_of_month
     acts_like?(:time) ? change(:day => 1, :hour => 0) : change(:day => 1)
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 92b8417150..28c8b53b78 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -186,6 +186,17 @@ class Time
     months_since(1)
   end
 
+  # Short-hand for months_ago(3)
+  def prev_quarter
+    months_ago(3)
+  end
+  alias_method :last_quarter, :prev_quarter
+
+  # Short-hand for months_since(3)
+  def next_quarter
+    months_since(3)
+  end
+
   # Returns number of days to start of this week, week starts on start_day (default is :monday).
   def days_to_week_start(start_day = :monday)
     start_day_number = DAYS_INTO_WEEK[start_day]
diff --git a/activesupport/test/core_ext/date_ext_test.rb b/activesupport/test/core_ext/date_ext_test.rb
index e14a137f84..088b74a29a 100644
--- a/activesupport/test/core_ext/date_ext_test.rb
+++ b/activesupport/test/core_ext/date_ext_test.rb
@@ -289,6 +289,18 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
     assert_equal Date.new(2004, 2, 29), Date.new(2004, 3, 31).last_month
   end
 
+  def test_next_quarter_on_31st
+    assert_equal Date.new(2005, 11, 30), Date.new(2005, 8, 31).next_quarter
+  end
+
+  def test_prev_quarter_on_31st
+    assert_equal Date.new(2004, 2, 29), Date.new(2004, 5, 31).prev_quarter
+  end
+
+  def test_last_quarter_on_31st
+    assert_equal Date.new(2004, 2, 29), Date.new(2004, 5, 31).last_quarter
+  end
+
   def test_yesterday_constructor
     assert_equal Date.current - 1, Date.yesterday
   end
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index 3da0825489..183d58482d 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -271,6 +271,18 @@ class DateTimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal DateTime.civil(2004, 2, 29), DateTime.civil(2004, 3, 31).last_month
   end
 
+  def test_next_quarter_on_31st
+    assert_equal DateTime.civil(2005, 11, 30), DateTime.civil(2005, 8, 31).next_quarter
+  end
+
+  def test_prev_quarter_on_31st
+    assert_equal DateTime.civil(2004, 2, 29), DateTime.civil(2004, 5, 31).prev_quarter
+  end
+
+  def test_last_quarter_on_31st
+    assert_equal DateTime.civil(2004, 2, 29), DateTime.civil(2004, 5, 31).last_quarter
+  end
+
   def test_xmlschema
     assert_match(/^1880-02-28T15:15:10\+00:?00$/, DateTime.civil(1880, 2, 28, 15, 15, 10).xmlschema)
     assert_match(/^1980-02-28T15:15:10\+00:?00$/, DateTime.civil(1980, 2, 28, 15, 15, 10).xmlschema)
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 15c04bedf7..d6f285598e 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -906,4 +906,17 @@ class TimeExtMarshalingTest < ActiveSupport::TestCase
     assert_equal t.to_f, unmarshaled.to_f
     assert_equal t, unmarshaled
   end
+
+
+  def test_next_quarter_on_31st
+    assert_equal Time.local(2005, 11, 30), Time.local(2005, 8, 31).next_quarter
+  end
+
+  def test_prev_quarter_on_31st
+    assert_equal Time.local(2004, 2, 29), Time.local(2004, 5, 31).prev_quarter
+  end
+
+  def test_last_quarter_on_31st
+    assert_equal Time.local(2004, 2, 29), Time.local(2004, 5, 31).last_quarter
+  end
 end
diff --git a/guides/source/active_support_core_extensions.textile b/guides/source/active_support_core_extensions.textile
index 40ef19cfbf..99b8bdd3fd 100644
--- a/guides/source/active_support_core_extensions.textile
+++ b/guides/source/active_support_core_extensions.textile
@@ -3045,6 +3045,27 @@ Date.new(2000, 1, 31).next_month # => Tue, 29 Feb 2000
 
 +prev_month+ is aliased to +last_month+.
 
+h6. +prev_quarter+, +next_quarter+
+
+Same as +prev_month+ and +next_month+. It returns the date with the same day in the previous or next quarter:
+
+<ruby>
+t = Time.local(2010, 5, 8) # => Sat, 08 May 2010
+t.prev_quarter             # => Mon, 08 Feb 2010
+t.next_quarter             # => Sun, 08 Aug 2010
+</ruby>
+
+If such a day does not exist, the last day of the corresponding month is returned:
+
+<ruby>
+Time.local(2000, 7, 31).prev_quarter  # => Sun, 30 Apr 2000
+Time.local(2000, 5, 31).prev_quarter  # => Tue, 29 Feb 2000
+Time.local(2000, 10, 31).prev_quarter # => Mon, 30 Oct 2000
+Time.local(2000, 11, 31).next_quarter # => Wed, 28 Feb 2001
+</ruby>
+
++prev_quarter+ is aliased to +last_quarter+.
+
 h6. +beginning_of_week+, +end_of_week+
 
 The methods +beginning_of_week+ and +end_of_week+ return the dates for the