display single files from gist

lib/jekyll/tags/gist.rb

@@ -2,16 +2,27 @@
 #
 # Example:
 #    {% gist 1234567 %}
+#    {% gist 1234567 file.rb %}
 
 module Jekyll
   class GistTag < Liquid::Tag
-    def initialize(tag_name, gist, tokens)
-      super
-      @gist = gist.strip
+    def render(context)
+      if tag_contents = @markup.match(/(\d+) (.*)/)
+        gist_id, filename = tag_contents[1].strip, tag_contents[2].strip
+        gist_script_tag(gist_id, filename)
+      else
+        "Error parsing gist id"
+      end
     end
 
-    def render(context)
-      "<script src=\"https://gist.github.com/#{@gist}.js\"> </script>"
+    private
+
+    def gist_script_tag(gist_id, filename=nil)
+      if filename.empty?
+        "<script src=\"https://gist.github.com/#{gist_id}.js\">\s</script>"
+      else
+        "<script src=\"https://gist.github.com/#{gist_id}.js?file=#{filename}\">\s</script>"
+      end
     end
   end
 end