add servlet context path middleware

will be used by functions yet-to-be-added

src/clj_jtwig/web/middleware.clj

@@ -0,0 +1,12 @@
+(ns clj-jtwig.web.middleware)
+
+(declare ^:dynamic *servlet-context-path*)
+
+(defn wrap-servlet-context-path
+  "Binds the current request's context path to a var which we can use in
+   various jtwig functions that need it without having to explicitly
+   pass the path in as a function parameter."
+  [handler]
+  (fn [req]
+    (binding [*servlet-context-path* (:context req)]
+      (handler req))))