this package makes julienschmidt's httprouter support group routing

router.go

package router

import (
	"github.com/julienschmidt/httprouter"
	"net/http"
)

var h http.Handler

// SRouter is a http.Handler that wraps httprouter.Router with additional features.
type SRouter struct {
	path   string
	router *httprouter.Router
}

// NewRouteGroup returns *SRouter with a new initialized httprouter.Router attached.
func NewGroup(r *httprouter.Router, path string) *SRouter {
	return &SRouter{router: r, path: path}
}

// joinPath check if path start with '/' or not and return full path
func (r *SRouter) joinPath(path string) string {
	if (r.path + path)[0] != '/' {
		panic("path should start with '/' in path '" + path + "'.")
	}

	return r.path + path
}

// Group returns new *SRouter with given path and middlewares.
// It should be used for handles which have same path prefix or common middlewares.
func (r *SRouter) Group(path string) *SRouter {

	//Strip trailing / (if present) as all added sub paths must start with a /
	if path[len(path)-1] == '/' {
		path = path[:len(path)-1]
	}
	return &SRouter{
		path:   r.joinPath(path),
		router: r.router,
	}
}

// Handle registers a new request handle combined with middlewares.
func (r *SRouter) Handle(method, path string, handle httprouter.Handle) {
	r.router.Handle(method, r.joinPath(path), handle)
}

// Handler is an adapter for http.Handler.
func (r *SRouter) Handler(method, path string, handler http.Handler) {
	handle := func(w http.ResponseWriter, req *http.Request, _ httprouter.Params) {
		handler.ServeHTTP(w, req)
	}
	r.Handle(method, path, handle)
}

// HandlerFunc is an adapter for http.HandlerFunc.
func (r *SRouter) HandlerFunc(method, path string, handler http.HandlerFunc) {
	r.Handler(method, path, handler)
}

// ServeHTTP is an adapter for httprouter.ServeHTTP
func (r *SRouter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	h = r.router
	h.ServeHTTP(w, req)
}

// GET is a shortcut for SRouter.Handle("GET", path, handle)
func (r *SRouter) GET(path string, handle httprouter.Handle) {
	r.Handle("GET", path, handle)
}

// HEAD is a shortcut for SRouter.Handle("HEAD", path, handle)
func (r *SRouter) HEAD(path string, handle httprouter.Handle) {
	r.Handle("HEAD", path, handle)
}

// OPTIONS is a shortcut for SRouter.Handle("OPTIONS", path, handle)
func (r *SRouter) OPTIONS(path string, handle httprouter.Handle) {
	r.Handle("OPTIONS", path, handle)
}

// POST is a shortcut for SRouter.Handle("POST", path, handle)
func (r *SRouter) POST(path string, handle httprouter.Handle) {
	r.Handle("POST", path, handle)
}

// PUT is a shortcut for SRouter.Handle("PUT", path, handle)
func (r *SRouter) PUT(path string, handle httprouter.Handle) {
	r.Handle("PUT", path, handle)
}

// PATCH is a shortcut for SRouter.Handle("PATCH", path, handle)
func (r *SRouter) PATCH(path string, handle httprouter.Handle) {
	r.Handle("PATCH", path, handle)
}

// DELETE is a shortcut for SRouter.Handle("DELETE", path, handle)
func (r *SRouter) DELETE(path string, handle httprouter.Handle) {
	r.Handle("DELETE", path, handle)
}