Added routing and subscribing

router.go

@@ -0,0 +1,77 @@
+package mqtt
+
+import (
+	"strings"
+	"sync"
+)
+
+type router struct {
+	routes []route
+	lock   sync.RWMutex
+}
+
+func newRouter() *router {
+	return &router{routes: []route{}, lock: sync.RWMutex{}}
+}
+
+type route struct {
+	topic   string
+	handler MessageHandler
+}
+
+func match(route []string, topic []string) bool {
+	if len(route) == 0 {
+		return len(topic) == 0
+	}
+
+	if len(topic) == 0 {
+		return route[0] == "#"
+	}
+
+	if route[0] == "#" {
+		return true
+	}
+
+	if (route[0] == "+") || (route[0] == topic[0]) {
+		return match(route[1:], topic[1:])
+	}
+	return false
+}
+
+func routeIncludesTopic(route, topic string) bool {
+	return match(routeSplit(route), strings.Split(topic, "/"))
+}
+
+func routeSplit(route string) []string {
+	var result []string
+	if strings.HasPrefix(route, "$share") {
+		result = strings.Split(route, "/")[2:]
+	} else {
+		result = strings.Split(route, "/")
+	}
+	return result
+}
+
+func (r *route) match(message *Message) bool {
+	return r.topic == message.Topic() || routeIncludesTopic(r.topic, message.Topic())
+}
+
+func (r *router) addRoute(topic string, handler MessageHandler) {
+	if handler != nil {
+		r.lock.Lock()
+		r.routes = append(r.routes, route{topic: topic, handler: handler})
+		r.lock.Unlock()
+	}
+}
+
+func (r *router) match(message *Message) []route {
+	routes := []route{}
+	r.lock.RLock()
+	for _, route := range r.routes {
+		if route.match(message) {
+			routes = append(routes, route)
+		}
+	}
+	r.lock.RUnlock()
+	return routes
+}