Add useEncodedPath option to router and routes (#190)

- Resolves a breaking change in #184

mux.go

@@ -53,6 +53,8 @@ type Router struct {
 	// This has no effect when go1.7+ is used, since the context is stored
 	// on the request itself.
 	KeepContext bool
+	// see Router.UseEncodedPath(). This defines a flag for all routes.
+	useEncodedPath bool
 }
 
 // Match matches registered routes against the request.
@@ -77,7 +79,10 @@ func (r *Router) Match(req *http.Request, match *RouteMatch) bool {
 // mux.Vars(request).
 func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	if !r.skipClean {
-		path := getPath(req)
+		path := req.URL.Path
+		if r.useEncodedPath {
+			path = getPath(req)
+		}
 		// Clean path to canonical form and redirect.
 		if p := cleanPath(path); p != path {
 
@@ -152,6 +157,21 @@ func (r *Router) SkipClean(value bool) *Router {
 	return r
 }
 
+// UseEncodedPath tells the router to match the encoded original path
+// to the routes.
+// For eg. "/path/foo%2Fbar/to" will match the path "/path/{var}/to".
+// This behavior has the drawback of needing to match routes against
+// r.RequestURI instead of r.URL.Path. Any modifications (such as http.StripPrefix)
+// to r.URL.Path will not affect routing when this flag is on and thus may
+// induce unintended behavior.
+//
+// If not called, the router will match the unencoded path to the routes.
+// For eg. "/path/foo%2Fbar/to" will match the path "/path/foo/bar/to"
+func (r *Router) UseEncodedPath() *Router {
+	r.useEncodedPath = true
+	return r
+}
+
 // ----------------------------------------------------------------------------
 // parentRoute
 // ----------------------------------------------------------------------------
@@ -189,7 +209,7 @@ func (r *Router) buildVars(m map[string]string) map[string]string {
 
 // NewRoute registers an empty route.
 func (r *Router) NewRoute() *Route {
-	route := &Route{parent: r, strictSlash: r.strictSlash, skipClean: r.skipClean}
+	route := &Route{parent: r, strictSlash: r.strictSlash, skipClean: r.skipClean, useEncodedPath: r.useEncodedPath}
 	r.routes = append(r.routes, route)
 	return route
 }