Allow different param names in different methods with same path scheme (#2209)

* Change methodHandler element type to methodContext

Signed-off-by: ortyomka <iurin.art@gmail.com>

* Allow different param names in the smae path with different methods

Signed-off-by: ortyomka <iurin.art@gmail.com>

* Rename methodContext to routeMethod
Add paramsCount in each node for perfomance

Signed-off-by: ortyomka <iurin.art@gmail.com>

* Add backtracking to nearest path

Signed-off-by: ortyomka <iurin.art@gmail.com>

* Remove params from NotAllowed

Signed-off-by: ortyomka <iurin.art@gmail.com>

router_test.go

@@ -2318,6 +2318,33 @@ func TestRouterPanicWhenParamNoRootOnlyChildsFailsFind(t *testing.T) {
 	}
 }
 
+// Issue #1726
+func TestRouterDifferentParamsInPath(t *testing.T) {
+	e := New()
+	r := e.router
+	r.Add(http.MethodPut, "/*", func(Context) error {
+		return nil
+	})
+	r.Add(http.MethodPut, "/users/:vid/files/:gid", func(Context) error {
+		return nil
+	})
+	r.Add(http.MethodGet, "/users/:uid/files/:fid", func(Context) error {
+		return nil
+	})
+	c := e.NewContext(nil, nil).(*context)
+
+	r.Find(http.MethodGet, "/users/1/files/2", c)
+	assert.Equal(t, "1", c.Param("uid"))
+	assert.Equal(t, "2", c.Param("fid"))
+
+	r.Find(http.MethodGet, "/users/1/shouldBacktrackToFirstAnyRouteAnd405", c)
+	assert.Equal(t, "/*", c.Path())
+
+	r.Find(http.MethodPut, "/users/3/files/4", c)
+	assert.Equal(t, "3", c.Param("vid"))
+	assert.Equal(t, "4", c.Param("gid"))
+}
+
 func TestRouterHandleMethodOptions(t *testing.T) {
 	e := New()
 	r := e.router
@@ -2380,7 +2407,7 @@ func TestRouterHandleMethodOptions(t *testing.T) {
 				assert.NoError(t, err)
 				assert.Equal(t, tc.expectStatus, rec.Code)
 			}
-			assert.Equal(t, tc.expectAllowHeader, c.Response().Header().Get("Allow"))
+			assert.Equal(t, tc.expectAllowHeader, c.Response().Header().Get(HeaderAllow))
 		})
 	}
 }