Add Occurrence class to handle end_time

Issue ice-cube-ruby#119

lib/ice_cube.rb

@@ -17,6 +17,7 @@ module IceCube
 
   autoload :Rule, 'ice_cube/rule'
   autoload :Schedule, 'ice_cube/schedule'
+  autoload :Occurrence, 'ice_cube/occurrence'
 
   autoload :IcalBuilder, 'ice_cube/builders/ical_builder'
   autoload :HashBuilder, 'ice_cube/builders/hash_builder'

lib/ice_cube/occurrence.rb

@@ -0,0 +1,64 @@
+require 'forwardable'
+require 'delegate'
+
+module IceCube
+
+  class Occurrence < SimpleDelegator
+
+    # Optimize for common methods to avoid method_missing
+    extend Forwardable
+    def_delegators :start_time, :to_s, :to_i, :<=>, :==
+    def_delegators :to_range, :cover?, :include?, :each, :first, :last
+
+    attr_reader :start_time, :end_time
+
+    def initialize(start_time, end_time=nil)
+      @start_time = start_time
+      @end_time = end_time || start_time
+      __setobj__ @start_time
+    end
+
+    def intersects? other
+      if other.is_a?(Occurrence) || other.is_a?(Range)
+        lower_bound_1 = first + 1
+        upper_bound_1 = last # exclude end
+        lower_bound_2 = other.first + 1
+        upper_bound_2 = other.last + 1
+        if (lower_bound_2 <=> upper_bound_2) > 0
+          false
+        elsif (lower_bound_1 <=> upper_bound_1) > 0
+          false
+        else
+          (upper_bound_1 <=> lower_bound_2) >= 0 and
+            (upper_bound_2 <=> lower_bound_1) >= 0
+        end
+      else
+        cover? other
+      end
+    end
+
+    def comparable_time
+      start_time
+    end
+
+    def duration
+      end_time - start_time
+    end
+
+    def to_range
+      start_time..end_time
+    end
+
+    def to_time
+      @start_time
+    end
+
+    def to_s
+      if duration > 0
+        "#{start_time} - #{end_time}"
+      else
+        "#{start_time}"
+      end
+    end
+  end
+end

spec/examples/active_support_spec.rb

@@ -86,3 +86,15 @@
   end
 
 end
+
+describe IceCube::Occurrence do
+
+  it 'can be subtracted from a time' do
+    start_time = Time.now
+    occurrence = Occurrence.new(start_time)
+
+    difference = (start_time + 60) - occurrence
+    difference.should == 60
+  end
+
+end

spec/examples/occurrence_spec.rb

@@ -0,0 +1,97 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+
+include IceCube
+
+describe Occurrence do
+
+  describe :to_s do
+    it "looks like a Time for a zero duration" do
+      start_time = Time.now
+      occurrence = Occurrence.new(start_time)
+
+      occurrence.to_s.should == start_time.to_s
+    end
+
+    it "looks like a range for a non-zero duration" do
+      start_time = Time.now
+      end_time = start_time + ONE_HOUR
+      occurrence = Occurrence.new(start_time, end_time)
+
+      occurrence.to_s.should == "#{start_time} - #{end_time}"
+    end
+  end
+
+  describe :end_time do
+
+    it 'defaults to start_time' do
+      start_time = Time.now
+      occurrence = Occurrence.new(start_time)
+
+      occurrence.end_time.should == start_time
+    end
+
+    it 'returns specified end_time' do
+      start_time = Time.now
+      end_time = start_time + 3600
+      occurrence = Occurrence.new(start_time, end_time)
+
+      occurrence.end_time.should == end_time
+    end
+
+  end
+
+  describe :arithmetic do
+
+    let(:start_time) { Time.now }
+    let(:occurrence) { Occurrence.new(start_time) }
+
+    it 'returns a time when adding' do
+      new_time = occurrence + 60
+      new_time.should == start_time + 60
+    end
+
+    it 'can get difference from a time' do
+      difference = occurrence - (start_time - 60)
+      difference.should == 60
+    end
+
+  end
+
+  describe :intersects? do
+
+    let(:start_time) { Time.now }
+    let(:end_time)   { start_time + 3600 }
+
+    it 'is true for a time during the occurrence' do
+      occurrence = Occurrence.new(start_time, end_time)
+
+      inclusion = occurrence.intersects? start_time + 1800
+      inclusion.should be_true
+    end
+
+    it 'is false for a time outside the occurrence' do
+      occurrence = Occurrence.new(start_time, end_time)
+
+      inclusion = occurrence.intersects? start_time + 3601
+      inclusion.should be_false
+    end
+
+    it 'is true for an intersecting occurrence' do
+      occurrence1 = Occurrence.new(start_time, end_time)
+      occurrence2 = Occurrence.new(start_time + 1, end_time + 1)
+
+      inclusion = occurrence1.intersects? occurrence2
+      inclusion.should be_true
+    end
+
+    it 'is false for a non-intersecting occurrence' do
+      occurrence1 = Occurrence.new(start_time, end_time)
+      occurrence2 = Occurrence.new(end_time)
+
+      inclusion = occurrence1.intersects? occurrence2
+      inclusion.should be_false
+    end
+  end
+
+end
+