Added Time#advance to do precise time time calculations for cases where a month being approximated to 30 days won't do (closes #1860) [Rick Olson]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3887 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 28 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 36db4dc605..ec676773bb 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Added Time#advance to do precise time time calculations for cases where a month being approximated to 30 days won't do #1860 [Rick Olson]
+
 * Enhance Inflector.underscore to convert '-' into '_' (as the inverse of Inflector.dasherize) [Jamis Buck]
 
 * Switched to_xml to use the xml schema format for datetimes.  This allows the encoding of time zones and should improve operability. [Koz]
diff --git a/activesupport/lib/active_support/core_ext/numeric/time.rb b/activesupport/lib/active_support/core_ext/numeric/time.rb
index a69a6c5f64..b4954e943f 100644
--- a/activesupport/lib/active_support/core_ext/numeric/time.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/time.rb
@@ -2,6 +2,9 @@ module ActiveSupport #:nodoc:
   module CoreExtensions #:nodoc:
     module Numeric #:nodoc:
       # Enables the use of time calculations and declarations, like 45.minutes + 2.hours + 4.years.
+      #
+      # If you need precise date calculations that doesn't just treat months as 30 days, then have
+      # a look at Time#advance.
       # 
       # Some of these methods are approximations, Ruby's core 
       # Date[http://stdlib.rubyonrails.org/libdoc/date/rdoc/index.html] and 
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 6a80762a62..7c60d5bed5 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -44,6 +44,15 @@ module ActiveSupport #:nodoc:
             options[:usec]  || ((options[:hour] || options[:min] || options[:sec]) ? 0 : self.usec)
           )
         end
+        
+        # Uses Date to provide precise Time calculations for years, months, and days.  The +options+ parameter takes a hash with 
+        # any of these keys: :months, :days, :years.
+        def advance(options)
+          d = ::Date.new(year + (options.delete(:years) || 0), month, day)
+          d = d >> options.delete(:months) if options[:months]
+          d = d +  options.delete(:days)   if options[:days]
+          change(options.merge(:year => d.year, :month => d.month, :mday => d.day))
+        end
 
         # Returns a new Time representing the time a number of seconds ago, this is basically a wrapper around the Numeric extension
         # Do not use this method in combination with x.months, use months_ago instead!
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 2100409dba..dee0a1f84e 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -129,7 +129,21 @@ class TimeExtCalculationsTest < Test::Unit::TestCase
     assert_equal Time.utc(2005,2,22,16,45),    Time.utc(2005,2,22,15,15,10).change(:hour => 16, :min => 45)
     assert_equal Time.utc(2005,2,22,15,45),    Time.utc(2005,2,22,15,15,10).change(:min => 45)
   end
+
+  def test_plus
+    assert_equal Time.local(2006,2,28,15,15,10), Time.local(2005,2,28,15,15,10).advance(:years => 1)
+    assert_equal Time.local(2005,6,28,15,15,10), Time.local(2005,2,28,15,15,10).advance(:months => 4)
+    assert_equal Time.local(2012,9,28,15,15,10), Time.local(2005,2,28,15,15,10).advance(:years => 7, :months => 7)
+    assert_equal Time.local(2013,10,3,15,15,10), Time.local(2005,2,28,15,15,10).advance(:years => 7, :months => 19, :days => 5)
+  end
   
+  def test_utc_plus
+    assert_equal Time.utc(2006,2,22,15,15,10), Time.utc(2005,2,22,15,15,10).advance(:years => 1)
+    assert_equal Time.utc(2005,6,22,15,15,10), Time.utc(2005,2,22,15,15,10).advance(:months => 4)
+    assert_equal Time.utc(2012,9,22,15,15,10), Time.utc(2005,2,22,15,15,10).advance(:years => 7, :months => 7)
+    assert_equal Time.utc(2013,10,3,15,15,10), Time.utc(2005,2,22,15,15,10).advance(:years => 7, :months => 19, :days => 11)
+  end
+
   def test_next_week
     assert_equal Time.local(2005,2,28), Time.local(2005,2,22,15,15,10).next_week
     assert_equal Time.local(2005,2,29), Time.local(2005,2,22,15,15,10).next_week(:tuesday)