Initial

.gitignore

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+*.sw?
+.DS_Store
+coverage
+rdoc
+pkg
+*.bundle
+*.so
+*.dll
+*.o
+Makefile
+*.gemspec

LICENSE

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+Copyright (c) 2009 Burke Libbey, Thorkelson Consulting Ltd.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Rakefile

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+require 'rubygems'
+require 'rake'
+

lib/business_days.rb

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+require 'active_support/all'
+require File.join(File.dirname(__FILE__),'business_days','time')
+
+module BusinessDays
+
+  class BusinessDayDuration
+    def initialize(days)
+      @days = days
+    end 
+
+    def calculate_duration(time, operation)
+      business_days = time.is_business_day? ? 1 : 0
+      while business_days <= @days
+        if (time = time.send(operation, 1.day)).is_business_day?
+          business_days += 1
+        end 
+      end 
+      time
+    end 
+
+    def +(time)
+      calculate_duration(time, :+)
+    end 
+
+  end 
+
+  def business_days
+    BusinessDayDuration.new(self)
+  end 
+  alias :business_day :business_days
+
+end 
+
+class Numeric
+  include BusinessDays
+end 

lib/business_days/time.rb

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+module BusinessDays
+  module Time
+    module Calculations
+      def self.included(base) #:nodoc:
+
+        base.class_eval do
+          alias_method :plus_without_business_days, :+
+          alias_method :+, :plus_with_business_days
+
+          alias_method :minus_without_business_days, :-
+          alias_method :-, :minus_with_business_days
+        end
+      end
+
+      def is_business_day?
+        # TODO: Holidays.
+        ! [0,6].include?(self.wday)
+      end 
+
+      def plus_with_business_days(other)
+        if BusinessDays::BusinessDayDuration === other
+          other.calculate_duration(self, :+)
+        else
+          plus_without_business_days(other)
+        end
+      end
+
+      def minus_with_business_days(other)
+        if BusinessDays::BusinessDayDuration === other
+          other.calculate_duration(self, :-)
+        else
+          minus_without_business_days(other)
+        end
+      end
+    end
+
+  end 
+end
+
+class Time
+  include BusinessDays::Time::Calculations
+end 

spec/business_days_spec.rb

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+require 'spec_helper'
+require File.join(File.dirname(__FILE__),'..','lib','business_days')
+
+describe BusinessDays do
+
+  before do
+    @friday = Time.parse("Friday, September 10th, 2010")
+    @thursday = @friday - 1.day
+    @saturday = @friday + 1.day
+    @monday = @friday + 3.days
+    @tuesday = @friday + 4.days
+  end 
+
+  it "should add properly" do
+    (@friday + 1.business_day).should == @monday
+    (@friday + 2.business_days).should == @tuesday
+    (@saturday + 1.business_days).should == @tuesday
+    (@saturday + 0.business_days).should == @monday
+  end 
+
+  it "should subtract properly" do
+    (@saturday - 0.business_days).should == @friday
+    (@saturday - 1.business_day).should == @thursday
+    (@monday - 1.business_days).should == @friday
+    (@monday - 0.business_days).should == @monday
+  end 
+
+  it "should add with the params reversed" do
+    (1.business_day + @friday).should == @monday
+  end 
+
+end 

spec/spec_helper.rb

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+require 'rubygems'
+
+# require something.
+
+gem "rspec", ">=1.2.5"
+
+Spec::Runner.configure do |config|
+
+end
+
+

spec/spec_opts.rb

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+--colour