Added ring.util.request/accept function

@@ -1,10 +1,34 @@
 (ns ring.util.request
   "Parse and interpret Ring requests"
-  (:require [clojure.string :as str]))
+  (:require [clojure.string :as str]
+            [clojure.walk :as walk]))
 
 (defn header-seq
   "Returns seq of values for the specified header. Multiple values can be
   encoded in one header key using a comma as a separator."
   [request key]
   (-> (get-in request [:headers (name key)])
       (str/split #"\s*,\s*")))
+
+(defn- parse-attr-map [attrs]
+  (->> (map #(str/split % #"=") attrs)
+       (into {})
+       (walk/keywordize-keys)))
+
+(defn- parse-accept-value [value]
+  (let [[value & attrs] (str/split value #"\s*;\s*")]
+    (-> (parse-attr-map attrs)
+        (update-in [:q] #(Double. (or % "1.0")))
+        (assoc :value value))))
+
+(defn accept
+  "Parse the accept header and returns an ordered seq of maps for each media
+  type. Each map will contain at least a :value and a :q key.
+
+  e.g. (accept {:headers {\"accept\": \"text/html, text/xml;q=0.8\"})
+
+       => ({:value \"text/html\", :q 1.0}
+           {:value \"text/xml\",  :q 0.8})"
+  [request]
+  (->> (header-seq request "accept")
+       (map parse-accept-value)))