Implemented EXP, INT, and MONTH functions

Gemfile

@@ -3,8 +3,9 @@ source 'http://rubygems.org'
 gem 'nokogiri'
 gem 'ffi'
 gem 'rubypeg'
+gem 'active_support'
 
 group :test do
   gem 'ZenTest'
   gem 'rspec'
-end
+end

spec/excel/excel_functions/exp_spec.rb

@@ -0,0 +1,29 @@
+require_relative '../../spec_helper.rb'
+
+describe "ExcelFunctions: EXP" do
+
+  it "should return the constant e when given a power of 1" do
+    FunctionTest.exp(1).should == Math::E
+  end
+
+  it "should return the the square of constant e when given a power of 2 (7.3890560989306495)" do
+    FunctionTest.exp(2).should == Math::E ** 2
+  end
+
+  it "should return an error when given inappropriate arguments" do
+    FunctionTest.exp("Asdasddf").should == :error
+  end
+
+  it "should treat nil as zero" do
+    FunctionTest.exp(nil).should == 0
+  end
+
+  it "should return an error if an argument is an error" do
+    FunctionTest.exp(:error).should == :error
+  end
+
+  it "should be in the list of functions that can be mapped to ruby" do
+    MapFormulaeToRuby::FUNCTIONS['EXP'].should == 'exp'
+  end
+
+end

spec/excel/excel_functions/int_spec.rb

@@ -0,0 +1,33 @@
+require_relative '../../spec_helper.rb'
+
+describe "ExcelFunctions: INT" do
+
+  it "should return 1 rounded to lowest integer (1.49)" do
+    FunctionTest.int(1.49).should == 1
+  end
+
+  it "should return 3 rounded to lowest integer (3.0723)" do
+    FunctionTest.int(3).should == 3
+  end
+
+  it "should return 7 rounded to lowest integer (7.9999999999)" do
+    FunctionTest.int(7).should == 7
+  end
+
+  it "should return an error when given inappropriate arguments" do
+    FunctionTest.int("Asdasddf").should == :error
+  end
+
+  it "should treat nil as zero" do
+    FunctionTest.int(nil).should == 0
+  end
+
+  it "should return an error if an argument is an error" do
+    FunctionTest.int(:error).should == :error
+  end
+
+  it "should be in the list of functions that can be mapped to ruby" do
+    MapFormulaeToRuby::FUNCTIONS['INT'].should == 'int'
+  end
+
+end

spec/excel/excel_functions/month_spec.rb

@@ -0,0 +1,25 @@
+require_relative '../../spec_helper.rb'
+
+describe "ExcelFunctions: MONTH" do
+
+  it "should return 3 when date is 03/26/2013 (serial: 41359)" do
+    FunctionTest.month(41359).should == 3
+  end
+
+  it "should return an error when given inappropriate arguments" do
+    FunctionTest.month("Asdasddf").should == :error
+  end
+
+  it "should treat nil as zero" do
+    FunctionTest.month(nil).should == 0
+  end
+
+  it "should return an error if an argument is an error" do
+    FunctionTest.month(:error).should == :error
+  end
+
+  it "should be in the list of functions that can be mapped to ruby" do
+    MapFormulaeToRuby::FUNCTIONS['MONTH'].should == 'month'
+  end
+
+end

src/compile/ruby/map_formulae_to_ruby.rb

@@ -23,15 +23,18 @@ class MapFormulaeToRuby < MapValuesToRuby
     'COSH' => 'cosh',
     'COUNT' => 'count',
     'COUNTA' => 'counta',
+    'EXP' => 'exp',
     'FIND' => 'find',
     'IF' => 'excel_if',
     'IFERROR' => 'iferror',
     'INDEX' => 'index',
+    'INT' => 'int',
     'LEFT' => 'left',
     'MATCH' => 'excel_match',
     'MAX' => 'max',
     'MIN' => 'min',
     'MOD' => 'mod',
+    'MONTH' => 'month',
     'PI' => 'pi',
     'PMT' => 'pmt',
     'ROUND' => 'round',

src/excel/excel_functions.rb

@@ -82,3 +82,9 @@ module ExcelFunctions
 require_relative 'excel_functions/rounddown'
 
 require_relative 'excel_functions/negative'
+
+require_relative 'excel_functions/exp'
+
+require_relative 'excel_functions/int'
+
+require_relative 'excel_functions/month'

src/excel/excel_functions/exp.rb

@@ -0,0 +1,11 @@
+module ExcelFunctions
+
+  def exp(a)
+    return 0 if a.nil?
+    return :error unless a.is_a? Numeric
+    a ||= 0
+    result = Math::E ** a
+    return result
+  end
+
+end

src/excel/excel_functions/int.rb

@@ -0,0 +1,11 @@
+module ExcelFunctions
+
+  def int(a)
+    return 0 if a.nil?
+    return :error unless a.is_a? Numeric
+    a ||= 0
+    result = a.to_s.split('.')[0].to_i
+    return result
+  end
+
+end

src/excel/excel_functions/month.rb

@@ -0,0 +1,16 @@
+require 'date'
+require 'active_support'
+require 'active_support/core_ext'
+
+module ExcelFunctions
+
+  def month(a)
+    return 0 if a.nil?
+    return :error unless a.is_a? Numeric
+    a ||= 0
+
+    result = (Date.civil(1899, 12, 31) + (a - 1).days).month
+    return result
+  end
+
+end