Refactor / extract the registry

Work in progress

iq.go

@@ -210,7 +210,7 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 			if level <= 1 {
 				var elt interface{}
 				payloadType := tt.Name.Space + " " + tt.Name.Local
-				if payloadType := typeRegistry[payloadType]; payloadType != nil {
+				if payloadType := iqTypeRegistry[payloadType]; payloadType != nil {
 					val := reflect.New(payloadType)
 					elt = val.Interface()
 				} else {
@@ -332,15 +332,9 @@ type DiscoItem struct {
 	Node    string   `xml:"node,attr,omitempty"`
 }
 
-// ============================================================================
-// TODO: Make it configurable at to be able to easily add new XMPP extensions
-//    in separate modules
-
-var typeRegistry = make(map[string]reflect.Type)
-
 func init() {
-	typeRegistry["http://jabber.org/protocol/disco#info query"] = reflect.TypeOf(DiscoInfo{})
-	typeRegistry["http://jabber.org/protocol/disco#items query"] = reflect.TypeOf(DiscoItems{})
-	typeRegistry["urn:ietf:params:xml:ns:xmpp-bind bind"] = reflect.TypeOf(BindBind{})
-	typeRegistry["urn:xmpp:iot:control set"] = reflect.TypeOf(iot.ControlSet{})
+	iqTypeRegistry["http://jabber.org/protocol/disco#info query"] = reflect.TypeOf(DiscoInfo{})
+	iqTypeRegistry["http://jabber.org/protocol/disco#items query"] = reflect.TypeOf(DiscoItems{})
+	iqTypeRegistry["urn:ietf:params:xml:ns:xmpp-bind bind"] = reflect.TypeOf(BindBind{})
+	iqTypeRegistry["urn:xmpp:iot:control set"] = reflect.TypeOf(iot.ControlSet{})
 }

message.go

@@ -3,7 +3,6 @@ package xmpp // import "gosrc.io/xmpp"
 import (
 	"encoding/xml"
 	"fmt"
-	"reflect"
 )
 
 // ============================================================================
@@ -87,21 +86,16 @@ func (msg *Message) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 		switch tt := t.(type) {
 
 		case xml.StartElement:
-			var elt interface{}
 			elementType := tt.Name.Space
-
-			if extensionType := msgTypeRegistry[elementType]; extensionType != nil {
-				val := reflect.New(extensionType)
-				elt = val.Interface()
-				if msgExt, ok := elt.(MsgExtension); ok {
-					err = d.DecodeElement(elt, &tt)
-					if err != nil {
-						return err
-					}
-					msg.Extensions = append(msg.Extensions, msgExt)
+			if msgExt := typeRegistry.getmsgType(elementType); msgExt != nil {
+				// Decode message extension
+				err = d.DecodeElement(msgExt, &tt)
+				if err != nil {
+					return err
 				}
+				msg.Extensions = append(msg.Extensions, msgExt)
 			} else {
-				// Decode default message elements
+				// Decode standard message sub-elements
 				var err error
 				switch tt.Name.Local {
 				case "body":
@@ -125,30 +119,3 @@ func (msg *Message) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 		}
 	}
 }
-
-// ============================================================================
-// Message extensions
-// Provide ability to add support to XMPP extension tags on messages
-
-type MsgExtension interface {
-	IsMsgExtension()
-}
-
-// XEP-0184
-type Receipt struct {
-	// xmlns: urn:xmpp:receipts
-	XMLName xml.Name
-	Id      string
-}
-
-func (*Receipt) IsMsgExtension() {}
-
-// ============================================================================
-// TODO: Make it configurable at to be able to easily add new XMPP extensions
-//    in separate modules
-
-var msgTypeRegistry = make(map[string]reflect.Type)
-
-func init() {
-	msgTypeRegistry["urn:xmpp:receipts"] = reflect.TypeOf(Receipt{})
-}

msg_receipts.go

@@ -0,0 +1,23 @@
+package xmpp
+
+import "encoding/xml"
+
+/*
+Support for:
+- XEP-0184 - Message Delivery Receipts: https://xmpp.org/extensions/xep-0184.html
+*/
+
+const (
+	NSReceipts = "urn:xmpp:receipts"
+)
+
+// XEP-0184 message receipt markers
+type Receipt struct {
+	MsgExtension
+	XMLName xml.Name
+	Id      string
+}
+
+func init() {
+	typeRegistry.RegisterMsgExt(NSReceipts, Receipt{})
+}

registry.go

@@ -0,0 +1,65 @@
+package xmpp
+
+import (
+	"reflect"
+	"sync"
+)
+
+type MsgExtension interface{}
+
+// The Registry for msg and IQ types is a global variable.
+// TODO: Move to the client init process to remove the dependency on a global variable.
+//   That should make it possible to be able to share the decoder.
+// TODO: Ensure that a client can add its own custom namespace to the registry (or overload existing ones).
+var typeRegistry = newRegistry()
+
+type namespace = string
+
+type registry struct {
+	// Key is namespace of message extension
+	msgTypes     map[namespace]reflect.Type
+	msgTypesLock *sync.RWMutex
+
+	iqTypes map[namespace]reflect.Type
+}
+
+func newRegistry() registry {
+	return registry{
+		msgTypes:     make(map[namespace]reflect.Type),
+		msgTypesLock: &sync.RWMutex{},
+		iqTypes:      make(map[namespace]reflect.Type),
+	}
+}
+
+// Mutexes are not needed when adding a Message or IQ extension in init function.
+// However, forcing the use of the mutex protect the data structure against unexpected use
+// of the registry by developers using the library.
+func (r registry) RegisterMsgExt(namespace string, extension MsgExtension) {
+	r.msgTypesLock.Lock()
+	defer r.msgTypesLock.Unlock()
+	r.msgTypes[namespace] = reflect.TypeOf(extension)
+}
+
+func (r registry) getMsgExtType(namespace string) reflect.Type {
+	r.msgTypesLock.RLock()
+	defer r.msgTypesLock.RUnlock()
+	return r.msgTypes[namespace]
+}
+
+func (r registry) getmsgType(namespace string) MsgExtension {
+	if extensionType := r.getMsgExtType(namespace); extensionType != nil {
+		val := reflect.New(extensionType)
+		elt := val.Interface()
+		if msgExt, ok := elt.(MsgExtension); ok {
+			return msgExt
+		}
+	}
+	return nil
+}
+
+// Registry to support message extensions
+//var msgTypeRegistry = make(map[string]reflect.Type)
+
+// Registry to instantiate the right IQ payload element
+// Key is namespace and key of the payload
+var iqTypeRegistry = make(map[string]reflect.Type)