middleware: Make SubRouter Match-aware

This helps avoid a gotcha when using matches with sub-routers.

Fixes #120.

web/middleware/subrouter.go

@@ -19,9 +19,23 @@ func (s subrouter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 		if ok {
 			oldpath := r.URL.Path
+			oldmatch := web.GetMatch(*s.c)
 			r.URL.Path = path
+			if oldmatch.Handler != nil {
+				delete(s.c.Env, web.MatchKey)
+			}
+
 			defer func() {
 				r.URL.Path = oldpath
+
+				if s.c.Env == nil {
+					return
+				}
+				if oldmatch.Handler != nil {
+					s.c.Env[web.MatchKey] = oldmatch
+				} else {
+					delete(s.c.Env, web.MatchKey)
+				}
 			}()
 		}
 	}

web/middleware/subrouter_test.go

@@ -0,0 +1,28 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/zenazn/goji/web"
+)
+
+func TestSubRouterMatch(t *testing.T) {
+	m := web.New()
+	m.Use(m.Router)
+
+	m2 := web.New()
+	m2.Use(SubRouter)
+	m2.Get("/bar", func(w http.ResponseWriter, r *http.Request) {})
+
+	m.Get("/foo/*", m2)
+
+	r, err := http.NewRequest("GET", "/foo/bar", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// This function will recurse forever if SubRouter + Match didn't work.
+	m.ServeHTTP(httptest.NewRecorder(), r)
+}