Extends support back to Ruby 2.0

This monkeypatches some core libraries.... I don't know that I'm ok with
it, but at the same time, I don't want to build in big icky hacks to
make it work on old Ruby. With this approach, when we decide to drop
2.0, we can just yank the monkeypatches.rb file and be done with it.

.travis.yml

@@ -14,6 +14,7 @@ matrix:
   include:
     - rvm: 2.0
       env: "CHECK=spec"
+      gemfile: Gemfile.ruby-2.0.x
 
     - rvm: 2.3
       env: "CHECK=spec"

Gemfile.ruby-2.0.x

@@ -0,0 +1,25 @@
+source 'https://rubygems.org'
+
+gemspec
+
+gem 'public_suffix', '2.0.5'
+gem 'i18n', '1.2.0'
+gem 'nokogiri', '1.6.8.1'
+
+group :development do
+  gem "turn"
+  gem "rack-test"
+  gem "pdf-inspector"
+end
+
+group :optional do
+  gem "pdfkit"
+end
+
+group :test do
+  gem 'rake'
+  gem 'rspec'
+  gem 'pry'
+end
+
+gem 'rack-contrib'

lib/showoff/compiler/form.rb

@@ -18,15 +18,18 @@ def self.render!(doc, options={})
     return unless title
 
     begin
-      tools = Nokogiri::XML::Node.new('div', doc).add_class('tools')
+      tools = Nokogiri::XML::Node.new('div', doc)
+        tools.add_class('tools')
         doc.add_child(tools)
 
-      button = Nokogiri::XML::Node.new('input', doc).add_class('display')
+      button = Nokogiri::XML::Node.new('input', doc)
+        button.add_class('display')
         button.set_attribute('type', 'button')
         button.set_attribute('value', I18n.t('forms.display'))
         tools.add_child(button)
 
-      submit = Nokogiri::XML::Node.new('input', doc).add_class('save')
+      submit = Nokogiri::XML::Node.new('input', doc)
+        submit.add_class('save')
         submit.set_attribute('type', 'submit')
         submit.set_attribute('value', I18n.t('forms.save'))
         submit.set_attribute('disabled', 'disabled')

lib/showoff/compiler/glossary.rb

@@ -25,7 +25,8 @@ def self.render!(doc)
       glossary = (item.attr('class').split - ['callout', 'glossary']).first
       address  = glossary ? "#{glossary}/#{$2}" : $2
 
-      link = Nokogiri::XML::Node.new('a', doc).add_class('processed label')
+      link = Nokogiri::XML::Node.new('a', doc)
+      link.add_class('processed label')
       link.set_attribute('href', "glossary://#{address}")
       link.content = $1
 
@@ -51,7 +52,8 @@ def self.render!(doc)
       label = link.clone
       label.add_class('label processed')
 
-      definition = Nokogiri::XML::Node.new('p', doc).add_class("callout glossary #{name}")
+      definition = Nokogiri::XML::Node.new('p', doc)
+      definition.add_class("callout glossary #{name}")
       definition.set_attribute('data-term', term)
       definition.set_attribute('data-text', text)
       definition.set_attribute('data-target', target)
@@ -84,7 +86,8 @@ def self.render!(doc)
   def self.generatePage!(doc)
       doc.search('.slide.glossary .content').each do |glossary|
         name = (glossary.attr('class').split - ['content', 'glossary']).first
-        list = Nokogiri::XML::Node.new('ul', doc).add_class('glossary terms')
+        list = Nokogiri::XML::Node.new('ul', doc)
+        list.add_class('glossary terms')
         seen = []
 
         doc.search('.callout.glossary').each do |item|
@@ -117,11 +120,13 @@ def self.generatePage!(doc)
 
           entry = Nokogiri::XML::Node.new('li', doc)
 
-          label = Nokogiri::XML::Node.new('a', doc).add_class('label')
+          label = Nokogiri::XML::Node.new('a', doc)
+          label.add_class('label')
           label.set_attribute('id', anchor)
           label.content = term
 
-          link = Nokogiri::XML::Node.new('a', doc).add_class('return')
+          link = Nokogiri::XML::Node.new('a', doc)
+          label.add_class('return')
           link.set_attribute('href', "##{href}")
           link.content = '↩'
 

lib/showoff/compiler/notes.rb

@@ -28,7 +28,8 @@ def self.render!(doc, profile, options = {})
       # Don't bother creating this if we don't want to use it
       next unless Showoff::Config.includeNotes?(klass)
 
-      notes = Nokogiri::XML::Node.new('div', doc).add_class("notes-section #{klass}")
+      notes = Nokogiri::XML::Node.new('div', doc)
+      notes.add_class("notes-section #{klass}")
       nodes = []
       iter = p.next_sibling
       until iter.text == '~~~ENDSECTION~~~' do

lib/showoff/compiler/table_of_contents.rb

@@ -26,7 +26,8 @@ def self.generate!(doc)
       title = heads.empty? ? slide['data-title'] : heads.first.text
       href  = "##{slide['id']}"
 
-      entry = Nokogiri::XML::Node.new('li', doc).add_class('tocentry')
+      entry = Nokogiri::XML::Node.new('li', doc)
+      entry.add_class('tocentry')
       link  = Nokogiri::XML::Node.new('a', doc)
       link.set_attribute('href', href)
       link.content = title
@@ -35,7 +36,8 @@ def self.generate!(doc)
       if (section and slide['data-section'] == section['data-section'])
         section.add_child(entry)
       else
-        section = Nokogiri::XML::Node.new('ol', doc).add_class('major')
+        section = Nokogiri::XML::Node.new('ol', doc)
+        section.add_class('major')
         section.set_attribute('data-section', slide['data-section'])
         entry.add_child(section)
         toc.add_child(entry)

lib/showoff/monkeypatches.rb

@@ -0,0 +1,28 @@
+# Yay for Ruby 2.0!
+class Hash
+  unless Hash.method_defined? :dig
+    def dig(*args)
+      args.reduce(self) do |iter, arg|
+        break nil unless iter.is_a? Enumerable
+        break nil unless iter.include? arg
+        iter[arg]
+      end
+    end
+  end
+
+end
+
+class Nokogiri::XML::Element
+  unless Nokogiri::XML::Element.method_defined? :add_class
+    def add_class(classlist)
+      self[:class] = [self[:class], classlist].join(' ')
+    end
+  end
+
+  unless Nokogiri::XML::Element.method_defined? :classes
+    def classes
+      self[:class] ? self[:class].split(' ') : []
+    end
+  end
+
+end

lib/showoff_ng.rb

@@ -6,6 +6,9 @@ class Showoff
   require 'showoff/locale'
   require 'showoff/logger'
 
+  # @todo: Do we really need Ruby 2.0 support?
+  require 'showoff/monkeypatches'
+
   GEMROOT = File.expand_path(File.join(File.dirname(__FILE__), '..'))
 
   def self.do_static(args, options)