add ordinal date permalink style (/YYYY/DDD/slug.html)

lib/jekyll/post.rb

@@ -146,6 +146,8 @@ module Jekyll
         "/:categories/:title.html"
       when :date
         "/:categories/:year/:month/:day/:title.html"
+      when :ordinal
+        "/:categories/:year/:y_day/:title.html"
       else
         self.site.permalink_style.to_s
       end
@@ -170,6 +172,7 @@ module Jekyll
           "i_month"    => date.strftime("%m").to_i.to_s,
           "categories" => categories.map { |c| URI.escape(c.to_s) }.join('/'),
           "short_month" => date.strftime("%b"),
+          "y_day"      => date.strftime("%j"),
           "output_ext" => self.output_ext
         }.inject(template) { |result, token|
           result.gsub(/:#{Regexp.escape token.first}/, token.last)

test/test_post.rb

@@ -214,6 +214,18 @@ class TestPost < Test::Unit::TestCase
           end
         end
 
+        context "with ordinal style" do
+          setup do
+            @post.site.permalink_style = :ordinal
+            @post.process(@fake_file)
+          end
+
+          should "process the url correctly" do
+            assert_equal "/:categories/:year/:y_day/:title.html", @post.template
+            assert_equal "/2008/253/foo-bar.html", @post.url
+          end
+        end
+
         context "with custom date permalink" do
           setup do
             @post.site.permalink_style = '/:categories/:year/:i_month/:i_day/:title/'