vlib: add eventbus module

vlib/eventbus/eventbus.v

@@ -0,0 +1,116 @@
+module eventbus
+
+pub struct Subscriber {
+	mut:
+	registry &Registry
+}
+struct Registry{
+	mut:
+	names []string
+	events []voidptr
+	once []string
+}
+
+struct EventHandler {
+	func fn(Params)
+}
+
+pub struct EventBus{
+	mut:
+	registry &Registry
+	pub:
+	subscriber Subscriber
+}
+
+// EventBus Methods
+
+pub fn new() &EventBus{
+	registry := &Registry{
+		names: []
+		events: []
+		once: []
+	}
+	return &EventBus{
+		registry,
+		Subscriber{registry}
+	}
+}
+
+pub fn (eb mut EventBus) publish(name string, p Params){
+	for i, n in eb.registry.names {
+		if name == n {
+			eh := eb.registry.events[i]
+			invoke(eh, p)
+			once_index := eb.registry.once.index(eb.registry.names[i])
+			if once_index > -1 {
+				eb.registry.events.delete(i)
+				eb.registry.names.delete(i)
+				eb.registry.once.delete(once_index)
+			}
+		}
+	}
+}
+
+pub fn (eb mut EventBus) clear_all(){
+	for i, n in eb.registry.names {
+		eb.registry.delete_entry(i)
+	}
+}
+
+pub fn (eb &EventBus) has_subscriber(name string) bool {
+	return eb.registry.check_subscriber(name)
+}
+
+// Subscriber Methods
+
+pub fn (s mut Subscriber) subscribe(name string, handler fn(Params)){
+	s.registry.names << name
+	v := voidptr(handler)
+	s.registry.events << v
+}
+
+pub fn (s mut Subscriber) subscribe_once(name string, handler fn(Params)){
+	s.subscribe(name, handler)
+	s.registry.once << name
+}
+
+pub fn (s &Subscriber) is_subscribed(name string) bool {
+	return s.registry.check_subscriber(name)
+}
+
+pub fn (s mut Subscriber) unsubscribe(name string, handler fn(Params)){
+	v := voidptr(handler)
+	for i, n in s.registry.names {
+		if name == n {
+			eh := s.registry.events[i]
+			if eh == v {
+				s.registry.delete_entry(i)
+			}
+		}
+	}
+}
+
+// Registry Methods
+
+fn (r &Registry) check_subscriber(name string) bool {
+	for n in r.names {
+		if name == n {return true}
+	}
+	return false
+}
+
+fn (r mut Registry) delete_entry(index int) {
+	once_index := r.once.index(r.names[index])
+	if once_index > -1 {
+		r.once.delete(once_index)
+	}
+	r.events.delete(index)
+	r.names.delete(index)
+}
+
+// Helper Functions
+
+fn invoke(p voidptr, arr Params){
+	handler := EventHandler{p}.func
+	handler(arr)
+}