Improve subroute configuration propagation #422

* Pull out common shared `routeConf` so that config is pushed on to child
routers and routes.
* Removes obsolete usages of `parentRoute`
* Add tests defining compositional behavior
* Exercise `copyRouteConf` for posterity

mux.go

@@ -50,24 +50,77 @@ type Router struct {
 	// Configurable Handler to be used when the request method does not match the route.
 	MethodNotAllowedHandler http.Handler
 
-	// Parent route, if this is a subrouter.
-	parent parentRoute
 	// Routes to be matched, in order.
 	routes []*Route
+
 	// Routes by name for URL building.
 	namedRoutes map[string]*Route
-	// See Router.StrictSlash(). This defines the flag for new routes.
+
-	strictSlash bool
-	// See Router.SkipClean(). This defines the flag for new routes.
-	skipClean bool
 	// If true, do not clear the request context after handling the request.
 	// 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
 	// Slice of middlewares to be called after a match is found
 	middlewares []middleware
+
+	// configuration shared with `Route`
+	routeConf
+}
+
+// common route configuration shared between `Router` and `Route`
+type routeConf struct {
+	// If true, "/path/foo%2Fbar/to" will match the path "/path/{var}/to"
+	useEncodedPath bool
+
+	// If true, when the path pattern is "/path/", accessing "/path" will
+	// redirect to the former and vice versa.
+	strictSlash bool
+
+	// If true, when the path pattern is "/path//to", accessing "/path//to"
+	// will not redirect
+	skipClean bool
+
+	// Manager for the variables from host and path.
+	regexp routeRegexpGroup
+
+	// List of matchers.
+	matchers []matcher
+
+	// The scheme used when building URLs.
+	buildScheme string
+
+	buildVarsFunc BuildVarsFunc
+}
+
+// returns an effective deep copy of `routeConf`
+func copyRouteConf(r routeConf) routeConf {
+	c := r
+
+	if r.regexp.path != nil {
+		c.regexp.path = copyRouteRegexp(r.regexp.path)
+	}
+
+	if r.regexp.host != nil {
+		c.regexp.host = copyRouteRegexp(r.regexp.host)
+	}
+
+	c.regexp.queries = make([]*routeRegexp, 0, len(r.regexp.queries))
+	for _, q := range r.regexp.queries {
+		c.regexp.queries = append(c.regexp.queries, copyRouteRegexp(q))
+	}
+
+	c.matchers = make([]matcher, 0, len(r.matchers))
+	for _, m := range r.matchers {
+		c.matchers = append(c.matchers, m)
+	}
+
+	return c
+}
+
+func copyRouteRegexp(r *routeRegexp) *routeRegexp {
+	c := *r
+	return &c
 }
 
 // Match attempts to match the given request against the router's registered routes.
@@ -164,13 +217,13 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 
 // Get returns a route registered with the given name.
 func (r *Router) Get(name string) *Route {
-	return r.getNamedRoutes()[name]
+	return r.namedRoutes[name]
 }
 
 // GetRoute returns a route registered with the given name. This method
 // was renamed to Get() and remains here for backwards compatibility.
 func (r *Router) GetRoute(name string) *Route {
-	return r.getNamedRoutes()[name]
+	return r.namedRoutes[name]
 }
 
 // StrictSlash defines the trailing slash behavior for new routes. The initial
@@ -221,51 +274,14 @@ func (r *Router) UseEncodedPath() *Router {
 	return r
 }
 
-// ----------------------------------------------------------------------------
-// parentRoute
-// ----------------------------------------------------------------------------
-
-func (r *Router) getBuildScheme() string {
-	if r.parent != nil {
-		return r.parent.getBuildScheme()
-	}
-	return ""
-}
-
-// getNamedRoutes returns the map where named routes are registered.
-func (r *Router) getNamedRoutes() map[string]*Route {
-	if r.namedRoutes == nil {
-		if r.parent != nil {
-			r.namedRoutes = r.parent.getNamedRoutes()
-		} else {
-			r.namedRoutes = make(map[string]*Route)
-		}
-	}
-	return r.namedRoutes
-}
-
-// getRegexpGroup returns regexp definitions from the parent route, if any.
-func (r *Router) getRegexpGroup() *routeRegexpGroup {
-	if r.parent != nil {
-		return r.parent.getRegexpGroup()
-	}
-	return nil
-}
-
-func (r *Router) buildVars(m map[string]string) map[string]string {
-	if r.parent != nil {
-		m = r.parent.buildVars(m)
-	}
-	return m
-}
-
 // ----------------------------------------------------------------------------
 // Route factories
 // ----------------------------------------------------------------------------
 
 // NewRoute registers an empty route.
 func (r *Router) NewRoute() *Route {
-	route := &Route{parent: r, strictSlash: r.strictSlash, skipClean: r.skipClean, useEncodedPath: r.useEncodedPath}
+	// initialize a route with a copy of the parent router's configuration
+	route := &Route{routeConf: copyRouteConf(r.routeConf), namedRoutes: r.namedRoutes}
 	r.routes = append(r.routes, route)
 	return route
 }

mux_test.go

@@ -48,15 +48,6 @@ type routeTest struct {
 }
 
 func TestHost(t *testing.T) {
-	// newRequestHost a new request with a method, url, and host header
-	newRequestHost := func(method, url, host string) *http.Request {
-		req, err := http.NewRequest(method, url, nil)
-		if err != nil {
-			panic(err)
-		}
-		req.Host = host
-		return req
-	}
 
 	tests := []routeTest{
 		{
@@ -1193,7 +1184,6 @@ func TestSubRouter(t *testing.T) {
 	subrouter3 := new(Route).PathPrefix("/foo").Subrouter()
 	subrouter4 := new(Route).PathPrefix("/foo/bar").Subrouter()
 	subrouter5 := new(Route).PathPrefix("/{category}").Subrouter()
-
 	tests := []routeTest{
 		{
 			route:        subrouter1.Path("/{v2:[a-z]+}"),
@@ -1288,6 +1278,106 @@ func TestSubRouter(t *testing.T) {
 			pathTemplate: `/{category}`,
 			shouldMatch:  true,
 		},
+		{
+			title:        "Mismatch method specified on parent route",
+			route:        new(Route).Methods("POST").PathPrefix("/foo").Subrouter().Path("/"),
+			request:      newRequest("GET", "http://localhost/foo/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/foo/",
+			pathTemplate: `/foo/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Match method specified on parent route",
+			route:        new(Route).Methods("POST").PathPrefix("/foo").Subrouter().Path("/"),
+			request:      newRequest("POST", "http://localhost/foo/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/foo/",
+			pathTemplate: `/foo/`,
+			shouldMatch:  true,
+		},
+		{
+			title:        "Mismatch scheme specified on parent route",
+			route:        new(Route).Schemes("https").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Match scheme specified on parent route",
+			route:        new(Route).Schemes("http").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  true,
+		},
+		{
+			title:        "No match header specified on parent route",
+			route:        new(Route).Headers("X-Forwarded-Proto", "https").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Header mismatch value specified on parent route",
+			route:        new(Route).Headers("X-Forwarded-Proto", "https").Subrouter().PathPrefix("/"),
+			request:      newRequestWithHeaders("GET", "http://localhost/", "X-Forwarded-Proto", "http"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Header match value specified on parent route",
+			route:        new(Route).Headers("X-Forwarded-Proto", "https").Subrouter().PathPrefix("/"),
+			request:      newRequestWithHeaders("GET", "http://localhost/", "X-Forwarded-Proto", "https"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  true,
+		},
+		{
+			title:        "Query specified on parent route not present",
+			route:        new(Route).Headers("key", "foobar").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Query mismatch value specified on parent route",
+			route:        new(Route).Queries("key", "foobar").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/?key=notfoobar"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  false,
+		},
+		{
+			title:        "Query match value specified on subroute",
+			route:        new(Route).Queries("key", "foobar").Subrouter().PathPrefix("/"),
+			request:      newRequest("GET", "http://localhost/?key=foobar"),
+			vars:         map[string]string{},
+			host:         "",
+			path:         "/",
+			pathTemplate: `/`,
+			shouldMatch:  true,
+		},
 		{
 			title:        "Build with scheme on parent router",
 			route:        new(Route).Schemes("ftp").Host("google.com").Subrouter().Path("/"),
@@ -1512,12 +1602,16 @@ func TestWalkSingleDepth(t *testing.T) {
 func TestWalkNested(t *testing.T) {
 	router := NewRouter()
 
-	g := router.Path("/g").Subrouter()
+	routeSubrouter := func(r *Route) (*Route, *Router) {
-	o := g.PathPrefix("/o").Subrouter()
+		return r, r.Subrouter()
-	r := o.PathPrefix("/r").Subrouter()
+	}
-	i := r.PathPrefix("/i").Subrouter()
+
-	l1 := i.PathPrefix("/l").Subrouter()
+	gRoute, g := routeSubrouter(router.Path("/g"))
-	l2 := l1.PathPrefix("/l").Subrouter()
+	oRoute, o := routeSubrouter(g.PathPrefix("/o"))
+	rRoute, r := routeSubrouter(o.PathPrefix("/r"))
+	iRoute, i := routeSubrouter(r.PathPrefix("/i"))
+	l1Route, l1 := routeSubrouter(i.PathPrefix("/l"))
+	l2Route, l2 := routeSubrouter(l1.PathPrefix("/l"))
 	l2.Path("/a")
 
 	testCases := []struct {
@@ -1525,12 +1619,12 @@ func TestWalkNested(t *testing.T) {
 		ancestors []*Route
 	}{
 		{"/g", []*Route{}},
-		{"/g/o", []*Route{g.parent.(*Route)}},
+		{"/g/o", []*Route{gRoute}},
-		{"/g/o/r", []*Route{g.parent.(*Route), o.parent.(*Route)}},
+		{"/g/o/r", []*Route{gRoute, oRoute}},
-		{"/g/o/r/i", []*Route{g.parent.(*Route), o.parent.(*Route), r.parent.(*Route)}},
+		{"/g/o/r/i", []*Route{gRoute, oRoute, rRoute}},
-		{"/g/o/r/i/l", []*Route{g.parent.(*Route), o.parent.(*Route), r.parent.(*Route), i.parent.(*Route)}},
+		{"/g/o/r/i/l", []*Route{gRoute, oRoute, rRoute, iRoute}},
-		{"/g/o/r/i/l/l", []*Route{g.parent.(*Route), o.parent.(*Route), r.parent.(*Route), i.parent.(*Route), l1.parent.(*Route)}},
+		{"/g/o/r/i/l/l", []*Route{gRoute, oRoute, rRoute, iRoute, l1Route}},
-		{"/g/o/r/i/l/l/a", []*Route{g.parent.(*Route), o.parent.(*Route), r.parent.(*Route), i.parent.(*Route), l1.parent.(*Route), l2.parent.(*Route)}},
+		{"/g/o/r/i/l/l/a", []*Route{gRoute, oRoute, rRoute, iRoute, l1Route, l2Route}},
 	}
 
 	idx := 0
@@ -1563,8 +1657,8 @@ func TestWalkSubrouters(t *testing.T) {
 	o.Methods("GET")
 	o.Methods("PUT")
 
-	// all 4 routes should be matched, but final 2 routes do not have path templates
+	// all 4 routes should be matched
-	paths := []string{"/g", "/g/o", "", ""}
+	paths := []string{"/g", "/g/o", "/g/o", "/g/o"}
 	idx := 0
 	err := router.Walk(func(route *Route, router *Router, ancestors []*Route) error {
 		path := paths[idx]
@@ -1745,7 +1839,11 @@ func testRoute(t *testing.T, test routeTest) {
 			}
 		}
 		if query != "" {
-			u, _ := route.URL(mapToPairs(match.Vars)...)
+			u, err := route.URL(mapToPairs(match.Vars)...)
+			if err != nil {
+				t.Errorf("(%v) erred while creating url: %v", test.title, err)
+				return
+			}
 			if query != u.RawQuery {
 				t.Errorf("(%v) URL query not equal: expected %v, got %v", test.title, query, u.RawQuery)
 				return
@@ -2332,6 +2430,273 @@ func testMethodsSubrouter(t *testing.T, test methodsSubrouterTest) {
 	}
 }
 
+func TestSubrouterMatching(t *testing.T) {
+	const (
+		none, stdOnly, subOnly uint8 = 0, 1 << 0, 1 << 1
+		both                         = subOnly | stdOnly
+	)
+
+	type request struct {
+		Name    string
+		Request *http.Request
+		Flags   uint8
+	}
+
+	cases := []struct {
+		Name                string
+		Standard, Subrouter func(*Router)
+		Requests            []request
+	}{
+		{
+			"pathPrefix",
+			func(r *Router) {
+				r.PathPrefix("/before").PathPrefix("/after")
+			},
+			func(r *Router) {
+				r.PathPrefix("/before").Subrouter().PathPrefix("/after")
+			},
+			[]request{
+				{"no match final path prefix", newRequest("GET", "/after"), none},
+				{"no match parent path prefix", newRequest("GET", "/before"), none},
+				{"matches append", newRequest("GET", "/before/after"), both},
+				{"matches as prefix", newRequest("GET", "/before/after/1234"), both},
+			},
+		},
+		{
+			"path",
+			func(r *Router) {
+				r.Path("/before").Path("/after")
+			},
+			func(r *Router) {
+				r.Path("/before").Subrouter().Path("/after")
+			},
+			[]request{
+				{"no match subroute path", newRequest("GET", "/after"), none},
+				{"no match parent path", newRequest("GET", "/before"), none},
+				{"no match as prefix", newRequest("GET", "/before/after/1234"), none},
+				{"no match append", newRequest("GET", "/before/after"), none},
+			},
+		},
+		{
+			"host",
+			func(r *Router) {
+				r.Host("before.com").Host("after.com")
+			},
+			func(r *Router) {
+				r.Host("before.com").Subrouter().Host("after.com")
+			},
+			[]request{
+				{"no match before", newRequestHost("GET", "/", "before.com"), none},
+				{"no match other", newRequestHost("GET", "/", "other.com"), none},
+				{"matches after", newRequestHost("GET", "/", "after.com"), none},
+			},
+		},
+		{
+			"queries variant keys",
+			func(r *Router) {
+				r.Queries("foo", "bar").Queries("cricket", "baseball")
+			},
+			func(r *Router) {
+				r.Queries("foo", "bar").Subrouter().Queries("cricket", "baseball")
+			},
+			[]request{
+				{"matches with all", newRequest("GET", "/?foo=bar&cricket=baseball"), both},
+				{"matches with more", newRequest("GET", "/?foo=bar&cricket=baseball&something=else"), both},
+				{"no match with none", newRequest("GET", "/"), none},
+				{"no match with some", newRequest("GET", "/?cricket=baseball"), none},
+			},
+		},
+		{
+			"queries overlapping keys",
+			func(r *Router) {
+				r.Queries("foo", "bar").Queries("foo", "baz")
+			},
+			func(r *Router) {
+				r.Queries("foo", "bar").Subrouter().Queries("foo", "baz")
+			},
+			[]request{
+				{"no match old value", newRequest("GET", "/?foo=bar"), none},
+				{"no match diff value", newRequest("GET", "/?foo=bak"), none},
+				{"no match with none", newRequest("GET", "/"), none},
+				{"matches override", newRequest("GET", "/?foo=baz"), none},
+			},
+		},
+		{
+			"header variant keys",
+			func(r *Router) {
+				r.Headers("foo", "bar").Headers("cricket", "baseball")
+			},
+			func(r *Router) {
+				r.Headers("foo", "bar").Subrouter().Headers("cricket", "baseball")
+			},
+			[]request{
+				{
+					"matches with all",
+					newRequestWithHeaders("GET", "/", "foo", "bar", "cricket", "baseball"),
+					both,
+				},
+				{
+					"matches with more",
+					newRequestWithHeaders("GET", "/", "foo", "bar", "cricket", "baseball", "something", "else"),
+					both,
+				},
+				{"no match with none", newRequest("GET", "/"), none},
+				{"no match with some", newRequestWithHeaders("GET", "/", "cricket", "baseball"), none},
+			},
+		},
+		{
+			"header overlapping keys",
+			func(r *Router) {
+				r.Headers("foo", "bar").Headers("foo", "baz")
+			},
+			func(r *Router) {
+				r.Headers("foo", "bar").Subrouter().Headers("foo", "baz")
+			},
+			[]request{
+				{"no match old value", newRequestWithHeaders("GET", "/", "foo", "bar"), none},
+				{"no match diff value", newRequestWithHeaders("GET", "/", "foo", "bak"), none},
+				{"no match with none", newRequest("GET", "/"), none},
+				{"matches override", newRequestWithHeaders("GET", "/", "foo", "baz"), none},
+			},
+		},
+		{
+			"method",
+			func(r *Router) {
+				r.Methods("POST").Methods("GET")
+			},
+			func(r *Router) {
+				r.Methods("POST").Subrouter().Methods("GET")
+			},
+			[]request{
+				{"matches before", newRequest("POST", "/"), none},
+				{"no match other", newRequest("HEAD", "/"), none},
+				{"matches override", newRequest("GET", "/"), none},
+			},
+		},
+		{
+			"schemes",
+			func(r *Router) {
+				r.Schemes("http").Schemes("https")
+			},
+			func(r *Router) {
+				r.Schemes("http").Subrouter().Schemes("https")
+			},
+			[]request{
+				{"matches overrides", newRequest("GET", "https://www.example.com/"), none},
+				{"matches original", newRequest("GET", "http://www.example.com/"), none},
+				{"no match other", newRequest("GET", "ftp://www.example.com/"), none},
+			},
+		},
+	}
+
+	// case -> request -> router
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			for _, req := range c.Requests {
+				t.Run(req.Name, func(t *testing.T) {
+					for _, v := range []struct {
+						Name     string
+						Config   func(*Router)
+						Expected bool
+					}{
+						{"subrouter", c.Subrouter, (req.Flags & subOnly) != 0},
+						{"standard", c.Standard, (req.Flags & stdOnly) != 0},
+					} {
+						r := NewRouter()
+						v.Config(r)
+						if r.Match(req.Request, &RouteMatch{}) != v.Expected {
+							if v.Expected {
+								t.Errorf("expected %v match", v.Name)
+							} else {
+								t.Errorf("expected %v no match", v.Name)
+							}
+						}
+					}
+				})
+			}
+		})
+	}
+}
+
+// verify that copyRouteConf copies fields as expected.
+func Test_copyRouteConf(t *testing.T) {
+	var (
+		m MatcherFunc = func(*http.Request, *RouteMatch) bool {
+			return true
+		}
+		b BuildVarsFunc = func(i map[string]string) map[string]string {
+			return i
+		}
+		r, _ = newRouteRegexp("hi", regexpTypeHost, routeRegexpOptions{})
+	)
+
+	tests := []struct {
+		name string
+		args routeConf
+		want routeConf
+	}{
+		{
+			"empty",
+			routeConf{},
+			routeConf{},
+		},
+		{
+			"full",
+			routeConf{
+				useEncodedPath: true,
+				strictSlash:    true,
+				skipClean:      true,
+				regexp:         routeRegexpGroup{host: r, path: r, queries: []*routeRegexp{r}},
+				matchers:       []matcher{m},
+				buildScheme:    "https",
+				buildVarsFunc:  b,
+			},
+			routeConf{
+				useEncodedPath: true,
+				strictSlash:    true,
+				skipClean:      true,
+				regexp:         routeRegexpGroup{host: r, path: r, queries: []*routeRegexp{r}},
+				matchers:       []matcher{m},
+				buildScheme:    "https",
+				buildVarsFunc:  b,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// special case some incomparable fields of routeConf before delegating to reflect.DeepEqual
+			got := copyRouteConf(tt.args)
+
+			// funcs not comparable, just compare length of slices
+			if len(got.matchers) != len(tt.want.matchers) {
+				t.Errorf("matchers different lengths: %v %v", len(got.matchers), len(tt.want.matchers))
+			}
+			got.matchers, tt.want.matchers = nil, nil
+
+			// deep equal treats nil slice differently to empty slice so check for zero len first
+			{
+				bothZero := len(got.regexp.queries) == 0 && len(tt.want.regexp.queries) == 0
+				if !bothZero && !reflect.DeepEqual(got.regexp.queries, tt.want.regexp.queries) {
+					t.Errorf("queries unequal: %v %v", got.regexp.queries, tt.want.regexp.queries)
+				}
+				got.regexp.queries, tt.want.regexp.queries = nil, nil
+			}
+
+			// funcs not comparable, just compare nullity
+			if (got.buildVarsFunc == nil) != (tt.want.buildVarsFunc == nil) {
+				t.Errorf("build vars funcs unequal: %v %v", got.buildVarsFunc == nil, tt.want.buildVarsFunc == nil)
+			}
+			got.buildVarsFunc, tt.want.buildVarsFunc = nil, nil
+
+			// finish the deal
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("route confs unequal: %v %v", got, tt.want)
+			}
+		})
+	}
+}
+
 // mapToPairs converts a string map to a slice of string pairs
 func mapToPairs(m map[string]string) []string {
 	var i int
@@ -2406,3 +2771,28 @@ func newRequest(method, url string) *http.Request {
 	}
 	return req
 }
+
+// create a new request with the provided headers
+func newRequestWithHeaders(method, url string, headers ...string) *http.Request {
+	req := newRequest(method, url)
+
+	if len(headers)%2 != 0 {
+		panic(fmt.Sprintf("Expected headers length divisible by 2 but got %v", len(headers)))
+	}
+
+	for i := 0; i < len(headers); i += 2 {
+		req.Header.Set(headers[i], headers[i+1])
+	}
+
+	return req
+}
+
+// newRequestHost a new request with a method, url, and host header
+func newRequestHost(method, url, host string) *http.Request {
+	req, err := http.NewRequest(method, url, nil)
+	if err != nil {
+		panic(err)
+	}
+	req.Host = host
+	return req
+}

regexp.go

@@ -267,7 +267,7 @@ type routeRegexpGroup struct {
 }
 
 // setMatch extracts the variables from the URL once a route matches.
-func (v *routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route) {
+func (v routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route) {
 	// Store host variables.
 	if v.host != nil {
 		host := getHost(req)

route.go

@@ -15,24 +15,8 @@ import (
 
 // Route stores information to match a request and build URLs.
 type Route struct {
-	// Parent where the route was registered (a Router).
-	parent parentRoute
 	// Request handler for the route.
 	handler http.Handler
-	// List of matchers.
-	matchers []matcher
-	// Manager for the variables from host and path.
-	regexp *routeRegexpGroup
-	// If true, when the path pattern is "/path/", accessing "/path" will
-	// redirect to the former and vice versa.
-	strictSlash bool
-	// If true, when the path pattern is "/path//to", accessing "/path//to"
-	// will not redirect
-	skipClean bool
-	// If true, "/path/foo%2Fbar/to" will match the path "/path/{var}/to"
-	useEncodedPath bool
-	// The scheme used when building URLs.
-	buildScheme string
 	// If true, this route never matches: it is only used to build URLs.
 	buildOnly bool
 	// The name used to build URLs.
@@ -40,7 +24,11 @@ type Route struct {
 	// Error resulted from building a route.
 	err error
 
-	buildVarsFunc BuildVarsFunc
+	// "global" reference to all named routes
+	namedRoutes map[string]*Route
+
+	// config possibly passed in from `Router`
+	routeConf
 }
 
 // SkipClean reports whether path cleaning is enabled for this route via
@@ -93,9 +81,7 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 	}
 
 	// Set variables.
-	if r.regexp != nil {
+	r.regexp.setMatch(req, match, r)
-		r.regexp.setMatch(req, match, r)
-	}
 	return true
 }
 
@@ -145,7 +131,7 @@ func (r *Route) Name(name string) *Route {
 	}
 	if r.err == nil {
 		r.name = name
-		r.getNamedRoutes()[name] = r
+		r.namedRoutes[name] = r
 	}
 	return r
 }
@@ -177,7 +163,6 @@ func (r *Route) addRegexpMatcher(tpl string, typ regexpType) error {
 	if r.err != nil {
 		return r.err
 	}
-	r.regexp = r.getRegexpGroup()
 	if typ == regexpTypePath || typ == regexpTypePrefix {
 		if len(tpl) > 0 && tpl[0] != '/' {
 			return fmt.Errorf("mux: path must start with a slash, got %q", tpl)
@@ -424,7 +409,7 @@ func (r *Route) Schemes(schemes ...string) *Route {
 	for k, v := range schemes {
 		schemes[k] = strings.ToLower(v)
 	}
-	if r.buildScheme == "" && len(schemes) > 0 {
+	if len(schemes) > 0 {
 		r.buildScheme = schemes[0]
 	}
 	return r.addMatcher(schemeMatcher(schemes))
@@ -439,7 +424,15 @@ type BuildVarsFunc func(map[string]string) map[string]string
 // BuildVarsFunc adds a custom function to be used to modify build variables
 // before a route's URL is built.
 func (r *Route) BuildVarsFunc(f BuildVarsFunc) *Route {
-	r.buildVarsFunc = f
+	if r.buildVarsFunc != nil {
+		// compose the old and new functions
+		old := r.buildVarsFunc
+		r.buildVarsFunc = func(m map[string]string) map[string]string {
+			return f(old(m))
+		}
+	} else {
+		r.buildVarsFunc = f
+	}
 	return r
 }
 
@@ -458,7 +451,8 @@ func (r *Route) BuildVarsFunc(f BuildVarsFunc) *Route {
 // Here, the routes registered in the subrouter won't be tested if the host
 // doesn't match.
 func (r *Route) Subrouter() *Router {
-	router := &Router{parent: r, strictSlash: r.strictSlash}
+	// initialize a subrouter with a copy of the parent route's configuration
+	router := &Router{routeConf: copyRouteConf(r.routeConf), namedRoutes: r.namedRoutes}
 	r.addMatcher(router)
 	return router
 }
@@ -502,9 +496,6 @@ func (r *Route) URL(pairs ...string) (*url.URL, error) {
 	if r.err != nil {
 		return nil, r.err
 	}
-	if r.regexp == nil {
-		return nil, errors.New("mux: route doesn't have a host or path")
-	}
 	values, err := r.prepareVars(pairs...)
 	if err != nil {
 		return nil, err
@@ -516,8 +507,8 @@ func (r *Route) URL(pairs ...string) (*url.URL, error) {
 			return nil, err
 		}
 		scheme = "http"
-		if s := r.getBuildScheme(); s != "" {
+		if r.buildScheme != "" {
-			scheme = s
+			scheme = r.buildScheme
 		}
 	}
 	if r.regexp.path != nil {
@@ -547,7 +538,7 @@ func (r *Route) URLHost(pairs ...string) (*url.URL, error) {
 	if r.err != nil {
 		return nil, r.err
 	}
-	if r.regexp == nil || r.regexp.host == nil {
+	if r.regexp.host == nil {
 		return nil, errors.New("mux: route doesn't have a host")
 	}
 	values, err := r.prepareVars(pairs...)
@@ -562,8 +553,8 @@ func (r *Route) URLHost(pairs ...string) (*url.URL, error) {
 		Scheme: "http",
 		Host:   host,
 	}
-	if s := r.getBuildScheme(); s != "" {
+	if r.buildScheme != "" {
-		u.Scheme = s
+		u.Scheme = r.buildScheme
 	}
 	return u, nil
 }
@@ -575,7 +566,7 @@ func (r *Route) URLPath(pairs ...string) (*url.URL, error) {
 	if r.err != nil {
 		return nil, r.err
 	}
-	if r.regexp == nil || r.regexp.path == nil {
+	if r.regexp.path == nil {
 		return nil, errors.New("mux: route doesn't have a path")
 	}
 	values, err := r.prepareVars(pairs...)
@@ -600,7 +591,7 @@ func (r *Route) GetPathTemplate() (string, error) {
 	if r.err != nil {
 		return "", r.err
 	}
-	if r.regexp == nil || r.regexp.path == nil {
+	if r.regexp.path == nil {
 		return "", errors.New("mux: route doesn't have a path")
 	}
 	return r.regexp.path.template, nil
@@ -614,7 +605,7 @@ func (r *Route) GetPathRegexp() (string, error) {
 	if r.err != nil {
 		return "", r.err
 	}
-	if r.regexp == nil || r.regexp.path == nil {
+	if r.regexp.path == nil {
 		return "", errors.New("mux: route does not have a path")
 	}
 	return r.regexp.path.regexp.String(), nil
@@ -629,7 +620,7 @@ func (r *Route) GetQueriesRegexp() ([]string, error) {
 	if r.err != nil {
 		return nil, r.err
 	}
-	if r.regexp == nil || r.regexp.queries == nil {
+	if r.regexp.queries == nil {
 		return nil, errors.New("mux: route doesn't have queries")
 	}
 	var queries []string
@@ -648,7 +639,7 @@ func (r *Route) GetQueriesTemplates() ([]string, error) {
 	if r.err != nil {
 		return nil, r.err
 	}
-	if r.regexp == nil || r.regexp.queries == nil {
+	if r.regexp.queries == nil {
 		return nil, errors.New("mux: route doesn't have queries")
 	}
 	var queries []string
@@ -683,7 +674,7 @@ func (r *Route) GetHostTemplate() (string, error) {
 	if r.err != nil {
 		return "", r.err
 	}
-	if r.regexp == nil || r.regexp.host == nil {
+	if r.regexp.host == nil {
 		return "", errors.New("mux: route doesn't have a host")
 	}
 	return r.regexp.host.template, nil
@@ -700,64 +691,8 @@ func (r *Route) prepareVars(pairs ...string) (map[string]string, error) {
 }
 
 func (r *Route) buildVars(m map[string]string) map[string]string {
-	if r.parent != nil {
-		m = r.parent.buildVars(m)
-	}
 	if r.buildVarsFunc != nil {
 		m = r.buildVarsFunc(m)
 	}
 	return m
 }
-
-// ----------------------------------------------------------------------------
-// parentRoute
-// ----------------------------------------------------------------------------
-
-// parentRoute allows routes to know about parent host and path definitions.
-type parentRoute interface {
-	getBuildScheme() string
-	getNamedRoutes() map[string]*Route
-	getRegexpGroup() *routeRegexpGroup
-	buildVars(map[string]string) map[string]string
-}
-
-func (r *Route) getBuildScheme() string {
-	if r.buildScheme != "" {
-		return r.buildScheme
-	}
-	if r.parent != nil {
-		return r.parent.getBuildScheme()
-	}
-	return ""
-}
-
-// getNamedRoutes returns the map where named routes are registered.
-func (r *Route) getNamedRoutes() map[string]*Route {
-	if r.parent == nil {
-		// During tests router is not always set.
-		r.parent = NewRouter()
-	}
-	return r.parent.getNamedRoutes()
-}
-
-// getRegexpGroup returns regexp definitions from this route.
-func (r *Route) getRegexpGroup() *routeRegexpGroup {
-	if r.regexp == nil {
-		if r.parent == nil {
-			// During tests router is not always set.
-			r.parent = NewRouter()
-		}
-		regexp := r.parent.getRegexpGroup()
-		if regexp == nil {
-			r.regexp = new(routeRegexpGroup)
-		} else {
-			// Copy.
-			r.regexp = &routeRegexpGroup{
-				host:    regexp.host,
-				path:    regexp.path,
-				queries: regexp.queries,
-			}
-		}
-	}
-	return r.regexp
-}