Pickle::Ref now has responsibility for parsing the index as an intege…

…r. The index word is available as #index_word

lib/pickle/ref.rb

@@ -7,8 +7,9 @@ class InvalidPickleRefError < RuntimeError
   # raises an error if the pickle_ref is invalid
   class Ref
     include Parser::Matchers
+    include Parser::Canonical
 
-    attr_reader :factory, :index, :label
+    attr_reader :factory, :index, :index_word, :label
 
     def initialize(string)
       parse_ref(string)
@@ -17,7 +18,8 @@ def initialize(string)
   protected
     def parse_ref(orig)
       str = orig.dup
-      @index = parse_index!(str)
+      @index_word = parse_index!(str)
+      @index = index_word_to_i(@index_word) if @index_word
       @factory = parse_factory!(str)
       @label = parse_label!(str)
       raise InvalidPickleRefError, "'#{orig}' has superfluous: '#{str}'" unless str.blank?
@@ -34,7 +36,7 @@ def parse_index!(string)
     # parse the factory name from the given string, remove the factory name and optional prefix
     # @return factory_name or nil
     def parse_factory!(string)
-      remove_from_and_return_1st_capture!(string, /^(?:#{match_prefix} )?(#{match_factory})/)
+      canonical remove_from_and_return_1st_capture!(string, /^(?:#{match_prefix} )?(#{match_factory})/)
     end
 
     # parse the label, removing it if found
@@ -49,5 +51,13 @@ def remove_from_and_return_1st_capture!(string, regexp)
         match_data[1]
       end
     end
+
+    def index_word_to_i(word)
+      case word
+      when 'last' then -1
+      when 'first' then 0
+      else word.gsub(/\D/,'').to_i - 1
+      end
+    end
   end
 end

spec/pickle/ref_spec.rb

@@ -5,9 +5,9 @@
     describe ".new 'colour'" do
       subject { Pickle::Ref.new('colour') }
 
-      its(:index)   { should be_nil }
+      its(:index) { should be_nil }
       its(:factory) { should == 'colour' }
-      its(:label)   { should be_nil }
+      its(:label) { should be_nil }
     end
 
     describe "with a prefix" do
@@ -31,22 +31,25 @@
     describe ".new('1st colour')" do
       subject { Pickle::Ref.new('1st colour') }
 
-      its(:index)   { should == '1st' }
+      its(:index_word) { should == '1st' }
+      its(:index) { should == 0 }
       its(:factory) { should == 'colour' }
-      its(:label)   { should be_nil }
+      its(:label) { should be_nil }
 
-      ['2nd', 'first', 'last', '3rd', '4th'].each do |index|
-        describe ".new('#{index} colour')" do
-          subject { Pickle::Ref.new("#{index} colour") }
+      {'2nd' => 1, 'first' => 0, 'last' => -1, '3rd' => 2, '4th' => 3}.each do |word, index|
+        describe ".new('#{word} colour')" do
+          subject { Pickle::Ref.new("#{word} colour") }
 
           its(:index) { should == index}
+          its(:index_word) { should == word }
         end
       end
 
       describe "the 2nd colour" do
         subject { Pickle::Ref.new('the 2nd colour') }
 
-        its(:index)   { should == '2nd' }
+        its(:index_word) { should == '2nd' }
+        its(:index) { should == 1 }
         its(:factory) { should == 'colour' }
       end
     end