Introduce ring.branch, add both ring.branch and related ring.static t…

…o README.

@@ -28,8 +28,10 @@ To see a more sophisticated Ring app, run:
 h2. All Available Libs
 
  * @ring.jetty@: Handler for the Jetty webserver.
+ * @ring.branch@: Middleware that proxies to one of multiple backing apps depending on the request uri.
  * @ring.file@: Middleware that serves static files out of a public directory.
  * @ring.file-info@: Middleware that augments response headers with info about File responses.
+ * @ring.static@: Middleware that serves static files with specified prefixes out of a public directory.
  * @ring.dump@: Endpoint that dumps the Ring requests as HTML responses for debugging.
  * @ring.show-exceptions@: Middleware that catches exceptions and displays readable backtraces for debugging.
  * @ring.reload@: Middleware to automatically reload selected libs before each requests, minimizing server restarts.

@@ -0,0 +1,24 @@
+(ns ring.branch)
+
+(defn wrap
+  "Returns an app that proxies to one of several possible backing apps depending
+  on the beginning of the request uri.
+  Should be passed an odd number of arguments - the inital pairs of arguments
+  indicate the branching conditions and corresponding apps, and the last
+  argument the fallback app that will be invoked if none of the branching
+  conditions are met:
+  
+  (wrap [\"/javascripts\" \"stylesheets\"] static-app
+        [\"/blog\"] blog-app
+        dynamic-app)"
+ [& branching]
+ (let [fallback     (last branching)
+       branch-logic
+         (map (fn [[prefixes branch]]
+                (fn [req]
+                  (let [uri (:uri req)]
+                    (if (some #(.startsWith uri %) prefixes) (branch req)))))
+              (partition 2 branching))]
+    (fn [req]
+      (or (some #(% req) branch-logic)
+          (fallback req)))))

@@ -0,0 +1,15 @@
+(ns ring.branch-test
+  (:use clj-unit.core ring.branch))
+
+(def wrapped
+  (wrap ["/javascripts" "/stylesheets"] (fn [req] [req :static])
+        ["/blog"] (fn [req] [req :blog])
+        (fn [req] [req :dynamic])))
+
+(deftest "wrap"
+  (let [req {:uri "/stylesheets"}]
+    (assert= [req :static] (wrapped req)))
+  (let [req {:uri "/blog/foo"}]
+    (assert= [req :blog] (wrapped req)))
+  (let [req {:uri "/foo/blog"}]
+    (assert= [req :dynamic] (wrapped req))))

@@ -6,5 +6,6 @@
   'ring.file-test
   'ring.file-info-test
   'ring.static-test
+  'ring.branch-test
   'ring.reload-test
   'ring.backtrace-test)