Added ability to compare date/time with infinity

Date, DateTime, Time and TimeWithZone can now be compared to infinity,
  so it's now possible to create ranges with one infinite bound and
  date/time object as another bound.

  Ex.: @range = Range.new(Date.today, Float::INFINITY)

Also it's possible to check inclusion of date/time in range with
  conversion.

  Ex.: @range.include?(Time.now + 1.year) # => true
       @range.include?(DateTime.now + 1.year) # => true

Ability to create date/time ranges with infinite bound is required
  for handling postgresql range types.

17 files changed, 199 insertions, 7 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 6917be7efc..bee93ebfbc 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,5 +1,18 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   It's now possible to compare Date, DateTime, Time and TimeWithZone with Infinity
+    This allows to create date/time ranges with one infinite bound.
+    Example:
+
+        range = Range.new(Date.today, Float::INFINITY)
+
+    Also it's possible to check inclusion of date/time in range with conversion.
+
+        range.include?(Time.now + 1.year)     # => true
+        range.include?(DateTime.now + 1.year) # => true
+
+    *Alexander Grebennik*
+
 *   Remove meaningless `ActiveSupport::FrozenObjectError`, which was just an alias of `RuntimeError`.
 
     *Akira Matsuda*
diff --git a/activesupport/lib/active_support/core_ext/date.rb b/activesupport/lib/active_support/core_ext/date.rb
index 465fedda80..5f13f5f70f 100644
--- a/activesupport/lib/active_support/core_ext/date.rb
+++ b/activesupport/lib/active_support/core_ext/date.rb
@@ -2,4 +2,5 @@ require 'active_support/core_ext/date/acts_like'
 require 'active_support/core_ext/date/calculations'
 require 'active_support/core_ext/date/conversions'
 require 'active_support/core_ext/date/zones'
+require 'active_support/core_ext/date/infinite_comparable'
 
diff --git a/activesupport/lib/active_support/core_ext/date/infinite_comparable.rb b/activesupport/lib/active_support/core_ext/date/infinite_comparable.rb
new file mode 100644
index 0000000000..ca5d793942
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date/infinite_comparable.rb
@@ -0,0 +1,5 @@
+require 'active_support/core_ext/infinite_comparable'
+
+class Date
+  include InfiniteComparable
+end
diff --git a/activesupport/lib/active_support/core_ext/date_time.rb b/activesupport/lib/active_support/core_ext/date_time.rb
index e8a27b9f38..024af91738 100644
--- a/activesupport/lib/active_support/core_ext/date_time.rb
+++ b/activesupport/lib/active_support/core_ext/date_time.rb
@@ -2,3 +2,4 @@ require 'active_support/core_ext/date_time/acts_like'
 require 'active_support/core_ext/date_time/calculations'
 require 'active_support/core_ext/date_time/conversions'
 require 'active_support/core_ext/date_time/zones'
+require 'active_support/core_ext/date_time/infinite_comparable'
diff --git a/activesupport/lib/active_support/core_ext/date_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
index fca5d4d679..4e4852a5e6 100644
--- a/activesupport/lib/active_support/core_ext/date_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
@@ -142,11 +142,4 @@ class DateTime
   def utc_offset
     (offset * 86400).to_i
   end
-
-  # Layers additional behavior on DateTime#<=> so that Time and
-  # ActiveSupport::TimeWithZone instances can be compared with a DateTime.
-  def <=>(other)
-    super other.to_datetime
-  end
-
 end
diff --git a/activesupport/lib/active_support/core_ext/date_time/infinite_comparable.rb b/activesupport/lib/active_support/core_ext/date_time/infinite_comparable.rb
new file mode 100644
index 0000000000..8a282b19f2
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date_time/infinite_comparable.rb
@@ -0,0 +1,5 @@
+require 'active_support/core_ext/infinite_comparable'
+
+class DateTime
+  include InfiniteComparable
+end
diff --git a/activesupport/lib/active_support/core_ext/infinite_comparable.rb b/activesupport/lib/active_support/core_ext/infinite_comparable.rb
new file mode 100644
index 0000000000..a69ff6a37b
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/infinite_comparable.rb
@@ -0,0 +1,30 @@
+require 'active_support/concern'
+
+module InfiniteComparable
+  extend ActiveSupport::Concern
+
+  included do
+    alias_method_chain :<=>, :infinity
+  end
+
+  define_method '<=>_with_infinity' do |other|
+    if other.class == self.class
+      self.send(:'<=>_without_infinity', other)
+    # inf <=> inf
+    elsif other.respond_to?(:infinite?) && other.infinite? && respond_to?(:infinite?) && infinite?
+      infinite? <=> other.infinite?
+    # not_inf <=> inf
+    elsif other.respond_to?(:infinite?) && other.infinite?
+      -other.infinite?
+    # inf <=> not_inf
+    elsif respond_to?(:infinite?) && infinite?
+      infinite?
+    else
+      conversion = :"to_#{self.class.name.downcase}"
+
+      other = other.send(conversion) if other.respond_to?(conversion)
+
+      self.send(:'<=>_without_infinity', other)
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/numeric.rb b/activesupport/lib/active_support/core_ext/numeric.rb
index a6bc0624be..d5cfc2ece4 100644
--- a/activesupport/lib/active_support/core_ext/numeric.rb
+++ b/activesupport/lib/active_support/core_ext/numeric.rb
@@ -1,3 +1,4 @@
 require 'active_support/core_ext/numeric/bytes'
 require 'active_support/core_ext/numeric/time'
 require 'active_support/core_ext/numeric/conversions'
+require 'active_support/core_ext/numeric/infinite_comparable'
diff --git a/activesupport/lib/active_support/core_ext/numeric/infinite_comparable.rb b/activesupport/lib/active_support/core_ext/numeric/infinite_comparable.rb
new file mode 100644
index 0000000000..07d4d7446a
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/numeric/infinite_comparable.rb
@@ -0,0 +1,11 @@
+require 'active_support/core_ext/big_decimal/conversions'
+require 'active_support/number_helper'
+require 'active_support/core_ext/infinite_comparable'
+
+class Float
+  include InfiniteComparable
+end
+
+class BigDecimal
+  include InfiniteComparable
+end
diff --git a/activesupport/lib/active_support/core_ext/time.rb b/activesupport/lib/active_support/core_ext/time.rb
index 32cffe237d..af6b589b71 100644
--- a/activesupport/lib/active_support/core_ext/time.rb
+++ b/activesupport/lib/active_support/core_ext/time.rb
@@ -3,3 +3,4 @@ require 'active_support/core_ext/time/calculations'
 require 'active_support/core_ext/time/conversions'
 require 'active_support/core_ext/time/marshal'
 require 'active_support/core_ext/time/zones'
+require 'active_support/core_ext/time/infinite_comparable'
diff --git a/activesupport/lib/active_support/core_ext/time/infinite_comparable.rb b/activesupport/lib/active_support/core_ext/time/infinite_comparable.rb
new file mode 100644
index 0000000000..63795885f5
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/time/infinite_comparable.rb
@@ -0,0 +1,5 @@
+require 'active_support/core_ext/infinite_comparable'
+
+class Time
+  include InfiniteComparable
+end
diff --git a/activesupport/test/core_ext/date_ext_test.rb b/activesupport/test/core_ext/date_ext_test.rb
index 5e89a6e00b..f8b219fee6 100644
--- a/activesupport/test/core_ext/date_ext_test.rb
+++ b/activesupport/test/core_ext/date_ext_test.rb
@@ -353,6 +353,13 @@ class DateExtBehaviorTest < ActiveSupport::TestCase
       Date.today.freeze.freeze
     end
   end
+
+  def test_compare_with_infinity
+    assert_nothing_raised do
+      assert_equal(-1, Date.today <=> Float::INFINITY)
+      assert_equal(1, Date.today <=> -Float::INFINITY)
+    end
+  end
 end
 
 class DateExtConversionsTest < ActiveSupport::TestCase
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index dfad3a90f8..1bcec7aac4 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -317,3 +317,12 @@ class DateTimeExtCalculationsTest < ActiveSupport::TestCase
       old_tz ? ENV['TZ'] = old_tz : ENV.delete('TZ')
     end
 end
+
+class DateTimeExtBehaviorTest < ActiveSupport::TestCase
+  def test_compare_with_infinity
+    assert_nothing_raised do
+      assert_equal(-1, DateTime.now <=> Float::INFINITY)
+      assert_equal(1, DateTime.now <=> -Float::INFINITY)
+    end
+  end
+end
diff --git a/activesupport/test/core_ext/numeric_ext_test.rb b/activesupport/test/core_ext/numeric_ext_test.rb
index 435f4aa5a1..5839aa40e5 100644
--- a/activesupport/test/core_ext/numeric_ext_test.rb
+++ b/activesupport/test/core_ext/numeric_ext_test.rb
@@ -447,3 +447,67 @@ class NumericExtFormattingTest < ActiveSupport::TestCase
     assert_equal '1 Million', BigDecimal("1000010").to_s(:human)
   end
 end
+
+class NumericExtBehaviorTest < ActiveSupport::TestCase
+  def setup
+    @inf = BigDecimal.new('Infinity')
+  end
+
+  def test_compare_infinity_with_date
+    assert_nothing_raised do
+      assert_equal(-1, -Float::INFINITY <=> Date.today)
+      assert_equal(1, Float::INFINITY <=> Date.today)
+      assert_equal(-1, -@inf <=> Date.today)
+      assert_equal(1, @inf <=> Date.today)
+    end
+  end
+
+  def test_compare_infinty_with_infinty
+    assert_nothing_raised do
+      assert_equal(-1, -Float::INFINITY <=> Float::INFINITY)
+      assert_equal(1, Float::INFINITY <=> -Float::INFINITY)
+      assert_equal(0, Float::INFINITY <=> Float::INFINITY)
+      assert_equal(0, -Float::INFINITY <=> -Float::INFINITY)
+
+      assert_equal(-1, -Float::INFINITY <=> BigDecimal::INFINITY)
+      assert_equal(1, Float::INFINITY <=> -BigDecimal::INFINITY)
+      assert_equal(0, Float::INFINITY <=> BigDecimal::INFINITY)
+      assert_equal(0, -Float::INFINITY <=> -BigDecimal::INFINITY)
+
+      assert_equal(-1, -BigDecimal::INFINITY <=> Float::INFINITY)
+      assert_equal(1, BigDecimal::INFINITY <=> -Float::INFINITY)
+      assert_equal(0, BigDecimal::INFINITY <=> Float::INFINITY)
+      assert_equal(0, -BigDecimal::INFINITY <=> -Float::INFINITY)
+    end
+  end
+
+  def test_compare_infinity_with_time
+    assert_nothing_raised do
+      assert_equal(-1, -Float::INFINITY <=> Time.now)
+      assert_equal(1, Float::INFINITY <=> Time.now)
+      assert_equal(-1, -@inf <=> Time.now)
+      assert_equal(1, @inf <=> Time.now)
+    end
+  end
+
+  def test_compare_infinity_with_datetime
+    assert_nothing_raised do
+      assert_equal(-1, -Float::INFINITY <=> DateTime.now)
+      assert_equal(1, Float::INFINITY <=> DateTime.now)
+      assert_equal(-1, -@inf <=> DateTime.now)
+      assert_equal(1, @inf <=> DateTime.now)
+    end
+  end
+
+  def test_compare_infinity_with_twz
+    time_zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = ActiveSupport::TimeWithZone.new(Time.now, time_zone)
+
+    assert_nothing_raised do
+      assert_equal(-1, -Float::INFINITY <=> twz)
+      assert_equal(1, Float::INFINITY <=> twz)
+      assert_equal(-1, -@inf <=> twz)
+      assert_equal(1, @inf <=> twz)
+    end
+  end
+end
diff --git a/activesupport/test/core_ext/range_ext_test.rb b/activesupport/test/core_ext/range_ext_test.rb
index f0cdc0bfd4..0051c48984 100644
--- a/activesupport/test/core_ext/range_ext_test.rb
+++ b/activesupport/test/core_ext/range_ext_test.rb
@@ -1,6 +1,7 @@
 require 'abstract_unit'
 require 'active_support/time'
 require 'active_support/core_ext/range'
+require 'active_support/core_ext/numeric'
 
 class RangeTest < ActiveSupport::TestCase
   def test_to_s_from_dates
@@ -85,4 +86,28 @@ class RangeTest < ActiveSupport::TestCase
     time_range_2 = Time.utc(2005, 12, 10, 17, 31)..Time.utc(2005, 12, 10, 18, 00)
     assert !time_range_1.overlaps?(time_range_2)
   end
+
+  def test_infinite_bounds
+    time_zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+
+    time = Time.now
+    date = Date.today
+    datetime = DateTime.now
+    twz = ActiveSupport::TimeWithZone.new(time, time_zone)
+
+    infinity1 = Float::INFINITY
+    infinity2 = BigDecimal.new('Infinity')
+
+    [infinity1, infinity2].each do |infinity|
+      [time, date, datetime, twz].each do |bound|
+        [time, date, datetime, twz].each do |value|
+          assert Range.new(bound, infinity).include?(value + 10.years)
+          assert Range.new(-infinity, bound).include?(value - 10.years)
+
+          assert !Range.new(bound, infinity).include?(value - 10.years)
+          assert !Range.new(-infinity, bound).include?(value + 10.years)
+        end
+      end
+    end
+  end
 end
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 70e07cefd1..1c75530084 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -843,3 +843,12 @@ class TimeExtMarshalingTest < ActiveSupport::TestCase
     assert_equal Time.local(2004, 2, 29), Time.local(2004, 5, 31).last_quarter
   end
 end
+
+class TimeExtBehaviorTest < ActiveSupport::TestCase
+  def test_compare_with_infinity
+    assert_nothing_raised do
+      assert_equal(-1, Time.now <=> Float::INFINITY)
+      assert_equal(1, Time.now <=> -Float::INFINITY)
+    end
+  end
+end
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 56020da035..76dc6a35c8 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -1081,3 +1081,15 @@ class TimeWithZoneMethodsForString < ActiveSupport::TestCase
       Time.zone = old_tz
     end
 end
+
+class TimeWithZoneExtBehaviorTest < ActiveSupport::TestCase
+  def test_compare_with_infinity
+    time_zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+    twz = ActiveSupport::TimeWithZone.new(Time.now, time_zone)
+
+    assert_nothing_raised do
+      assert_equal(-1, twz <=> Float::INFINITY)
+      assert_equal(1, twz <=> -Float::INFINITY)
+    end
+  end
+end