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router_root.go
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router_root.go
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// Copyright (c) 2018 Palantir Technologies. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package wrouter
import (
"context"
"net/http"
"sort"
)
type RootRouter interface {
http.Handler
Router
AddRequestHandlerMiddleware(handlers ...RequestHandlerMiddleware)
AddRouteHandlerMiddleware(handlers ...RouteHandlerMiddleware)
}
type rootRouter struct {
// impl stores the underlying RouterImpl used to route requests.
impl RouterImpl
// reqHandlers specifies the handlers that run for every request received by the router. Every request received by
// the router (including requests to methods/paths that are not registered on the router) is handled by these
// handlers in order before being handled by the underlying RouterImpl.
reqHandlers []RequestHandlerMiddleware
// routeHandlers specifies the handlers that are run for all of the routes that are registered on this router.
// Requests that are routed to a registered route on this router are handled by these handlers in order before being
// handled by the registered handler.
routeHandlers []RouteHandlerMiddleware
// routes stores all of the routes that are registered on this router.
routes []RouteSpec
// cachedHandler stores the http.Handler created by chaining all of the request handlers in reqHandlers with the
// request handler provided by impl. This is done because this http.Handler is called on every request and
// reqHandlers rarely changes, so it is much more efficient to cache the handler rather than creating a chained one
// on every request.
cachedHandler http.Handler
}
func New(impl RouterImpl, params ...RootRouterParam) RootRouter {
r := &rootRouter{
impl: impl,
}
for _, p := range params {
if p == nil {
continue
}
p.configure(r)
}
r.updateCachedHandler()
return r
}
type RootRouterParam interface {
configure(*rootRouter)
}
type rootRouterParamsFunc func(*rootRouter)
func (f rootRouterParamsFunc) configure(r *rootRouter) {
f(r)
}
func RootRouterParamAddRequestHandlerMiddleware(reqHandler ...RequestHandlerMiddleware) RootRouterParam {
return rootRouterParamsFunc(func(r *rootRouter) {
r.AddRequestHandlerMiddleware(reqHandler...)
})
}
func RootRouterParamAddRouteHandlerMiddleware(routeReqHandler ...RouteHandlerMiddleware) RootRouterParam {
return rootRouterParamsFunc(func(r *rootRouter) {
r.AddRouteHandlerMiddleware(routeReqHandler...)
})
}
func (r *rootRouter) updateCachedHandler() {
r.cachedHandler = createRequestHandler(r.impl, r.reqHandlers)
}
func (r *rootRouter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
r.cachedHandler.ServeHTTP(w, req)
}
func (r *rootRouter) Register(method, path string, handler http.Handler, params ...RouteParam) error {
pathTemplate, err := NewPathTemplate(path)
if err != nil {
return err
}
var pathVarNames []string
for _, segment := range pathTemplate.Segments() {
if segment.Type == LiteralSegment {
continue
}
pathVarNames = append(pathVarNames, segment.Value)
}
routeSpec := RouteSpec{
Method: method,
PathTemplate: pathTemplate.Template(),
}
r.routes = append(r.routes, routeSpec)
sort.Sort(routeSpecs(r.routes))
// wrap provided handler with a handler that registers the path parameter information in the context
r.impl.Register(method, pathTemplate.Segments(), http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
// register path parameters in context
pathParamVals := r.impl.PathParams(req, pathVarNames)
req = req.WithContext(context.WithValue(req.Context(), pathParamsContextKey, pathParamVals))
wrappedHandlerFn := createRouteRequestHandler(func(rw http.ResponseWriter, r *http.Request, reqVals RequestVals) {
handler.ServeHTTP(rw, r)
}, r.routeHandlers)
wrappedHandlerFn(w, req, RequestVals{
Spec: routeSpec,
PathParamVals: pathParamVals,
ParamPerms: toRequestParamPerms(params),
})
}))
return nil
}
func (r *routeRequestHandlerWithNext) HandleRequest(rw http.ResponseWriter, req *http.Request, reqVals RequestVals) {
r.handler(rw, req, reqVals, r.next)
}
func (r *rootRouter) RegisteredRoutes() []RouteSpec {
ris := make([]RouteSpec, len(r.routes))
copy(ris, r.routes)
return ris
}
func (r *rootRouter) Get(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodGet, path, handler, params...)
}
func (r *rootRouter) Head(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodHead, path, handler, params...)
}
func (r *rootRouter) Post(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodPost, path, handler, params...)
}
func (r *rootRouter) Put(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodPut, path, handler, params...)
}
func (r *rootRouter) Patch(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodPatch, path, handler, params...)
}
func (r *rootRouter) Delete(path string, handler http.Handler, params ...RouteParam) error {
return r.Register(http.MethodDelete, path, handler, params...)
}
func (r *rootRouter) Subrouter(path string) Router {
return &subrouter{
rPath: path,
rParent: r,
}
}
func (r *rootRouter) Path() string {
return ""
}
func (r *rootRouter) Parent() Router {
return nil
}
func (r *rootRouter) RootRouter() RootRouter {
return r
}
func (r *rootRouter) AddRequestHandlerMiddleware(handlers ...RequestHandlerMiddleware) {
r.reqHandlers = append(r.reqHandlers, handlers...)
r.updateCachedHandler()
}
func (r *rootRouter) AddRouteHandlerMiddleware(handlers ...RouteHandlerMiddleware) {
r.routeHandlers = append(r.routeHandlers, handlers...)
}
type requestHandlerWithNext struct {
handler RequestHandlerMiddleware
next http.Handler
}
func createRequestHandler(baseHandler http.Handler, handlers []RequestHandlerMiddleware) http.Handler {
if len(handlers) == 0 {
return baseHandler
}
return &requestHandlerWithNext{
handler: handlers[0],
next: createRequestHandler(baseHandler, handlers[1:]),
}
}
func (r *requestHandlerWithNext) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
r.handler(rw, req, r.next)
}
type routeRequestHandlerWithNext struct {
handler RouteHandlerMiddleware
next RouteRequestHandler
}
func createRouteRequestHandler(baseHandler RouteRequestHandler, handlers []RouteHandlerMiddleware) RouteRequestHandler {
if len(handlers) == 0 {
return baseHandler
}
return (&routeRequestHandlerWithNext{
handler: handlers[0],
next: createRouteRequestHandler(baseHandler, handlers[1:]),
}).HandleRequest
}