github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=

// NewRouter returns a new router instance.
func NewRouter() *Router {
	return &Router{namedRoutes: make(map[string]*Route)}
}

// Router registers routes to be matched and dispatches a handler.
//
// It implements the http.Handler interface, so it can be registered to serve
// requests:
//
//     var router = mux.NewRouter()
//
//     func main() {
//         http.Handle("/", router)
//     }
//
// Or, for Google App Engine, register it in a init() function:
//
//     func init() {
//         http.Handle("/", router)
//     }
//
// This will send all incoming requests to the router.
type Router struct {
	// Configurable Handler to be used when no route matches.
	NotFoundHandler http.Handler

	// Configurable Handler to be used when the request method does not match the route.
	MethodNotAllowedHandler http.Handler

	// Routes to be matched, in order.
	routes []*Route

	// Routes by name for URL building.
	namedRoutes map[string]*Route

	// If true, do not clear the request context after handling the request.
	//
	// Deprecated: No effect, since the context is stored on the request itself.
	KeepContext bool

	// Slice of middlewares to be called after a match is found
	middlewares []middleware

	// configuration shared with `Route`
	routeConf
}

// 中略...

// NewRoute registers an empty route.
func (r *Router) NewRoute() *Route {
	// 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
}

// 中略...

// HandleFunc registers a new route with a matcher for the URL path.
// See Route.Path() and Route.HandlerFunc().
func (r *Router) HandleFunc(path string, f func(http.ResponseWriter,
	*http.Request)) *Route {
	return r.NewRoute().Path(path).HandlerFunc(f)
}

type Route struct {
	// Request handler for the route.
	handler http.Handler
	// If true, this route never matches: it is only used to build URLs.
	buildOnly bool
	// The name used to build URLs.
	name string
	// Error resulted from building a route.
	err error

	// "global" reference to all named routes
	namedRoutes map[string]*Route

	// config possibly passed in from `Router`
	routeConf
}

// 中略

// Handler --------------------------------------------------------------------

// Handler sets a handler for the route.
func (r *Route) Handler(handler http.Handler) *Route {
	if r.err == nil {
		r.handler = handler
	}
	return r
}

// HandlerFunc sets a handler function for the route.
func (r *Route) HandlerFunc(f func(http.ResponseWriter, *http.Request)) *Route {
	return r.Handler(http.HandlerFunc(f))
}

// GetHandler returns the handler for the route, if any.
func (r *Route) GetHandler() http.Handler {
	return r.handler
}

// 中略...

// addRegexpMatcher adds a host or path matcher and builder to a route.
func (r *Route) addRegexpMatcher(tpl string, typ regexpType) error {
	if r.err != nil {
		return r.err
	}
	if typ == regexpTypePath || typ == regexpTypePrefix {
		if len(tpl) > 0 && tpl[0] != '/' {
			return fmt.Errorf("mux: path must start with a slash, got %q", tpl)
		}
		if r.regexp.path != nil {
			tpl = strings.TrimRight(r.regexp.path.template, "/") + tpl
		}
	}
	rr, err := newRouteRegexp(tpl, typ, routeRegexpOptions{
		strictSlash:    r.strictSlash,
		useEncodedPath: r.useEncodedPath,
	})
	if err != nil {
		return err
	}
	for _, q := range r.regexp.queries {
		if err = uniqueVars(rr.varsN, q.varsN); err != nil {
			return err
		}
	}
	if typ == regexpTypeHost {
		if r.regexp.path != nil {
			if err = uniqueVars(rr.varsN, r.regexp.path.varsN); err != nil {
				return err
			}
		}
		r.regexp.host = rr
	} else {
		if r.regexp.host != nil {
			if err = uniqueVars(rr.varsN, r.regexp.host.varsN); err != nil {
				return err
			}
		}
		if typ == regexpTypeQuery {
			r.regexp.queries = append(r.regexp.queries, rr)
		} else {
			r.regexp.path = rr
		}
	}
	r.addMatcher(rr)
	return nil
}

// 中略...

// Path -----------------------------------------------------------------------

// Path adds a matcher for the URL path.
// It accepts a template with zero or more URL variables enclosed by {}. The
// template must start with a "/".
// Variables can define an optional regexp pattern to be matched:
//
// - {name} matches anything until the next slash.
//
// - {name:pattern} matches the given regexp pattern.
//
// For example:
//
//     r := mux.NewRouter()
//     r.Path("/products/").Handler(ProductsHandler)
//     r.Path("/products/{key}").Handler(ProductsHandler)
//     r.Path("/articles/{category}/{id:[0-9]+}").
//       Handler(ArticleHandler)
//
// Variable names must be unique in a given route. They can be retrieved
// calling mux.Vars(request).
func (r *Route) Path(tpl string) *Route {
	r.err = r.addRegexpMatcher(tpl, regexpTypePath)
	return r
}