Allow placeholders in permalinks

lib/jekyll/url.rb

@@ -37,11 +37,11 @@ module Jekyll
     #
     # Returns the String URL
     def to_s
-      sanitize_url(@permalink || generate_url)
+      sanitize_url(generate_permalink_url || generate_url)
     end
 
     # Internal: Generate the URL by replacing all placeholders with their
-    # respective values
+    # respective values in the template
     #
     # Returns the _unsanitizied_ String URL
     def generate_url
@@ -51,6 +51,19 @@ module Jekyll
       end
     end
 
+    # Internal: Generate the URL by replacing all placeholders with their
+    # respective values in the permalink
+    #
+    # Returns the _unsanitizied_ String URL
+    def generate_permalink_url
+      if not @permalink.nil?
+        @placeholders.inject(@permalink) do |result, token|
+          break result if result.index(':').nil?
+          result.gsub(/:#{token.first}/, self.class.escape_path(token.last))
+        end
+      end
+    end
+
     # Returns a sanitized String URL
     def sanitize_url(in_url)
       url = in_url \

test/test_url.rb

@@ -23,7 +23,7 @@ class TestURL < Test::Unit::TestCase
       ).to_s
     end
 
-    should "return permalink if given" do
+    should "use permalink if given" do
       assert_equal "/le/perma/link", URL.new(
         :template => "/:x/:y",
         :placeholders => {:x => "foo", :y => "bar"},
@@ -31,5 +31,21 @@ class TestURL < Test::Unit::TestCase
       ).to_s
     end
 
+    should "replace placeholders in permalinks" do
+      assert_equal "/foo/bar", URL.new(
+        :template => "/baz",
+        :permalink => "/:x/:y",
+        :placeholders => {:x => "foo", :y => "bar"}
+      ).to_s
+    end
+
+    should "handle multiple of the same key in the permalink" do
+      assert_equal '/foo/bar/foo/', URL.new(
+        :template => "/baz",
+        :permalink => "/:x/:y/:x/",
+        :placeholders => {:x => "foo", :y => "bar"}
+      ).to_s
+    end
+
   end
 end