all derived class use final keyword

ixwebsocket/IXSelectInterruptEventFd.h

@@ -13,7 +13,7 @@
 
 namespace ix
 {
-    class SelectInterruptEventFd : public SelectInterrupt {
+    class SelectInterruptEventFd final : public SelectInterrupt {
     public:
         SelectInterruptEventFd();
         virtual ~SelectInterruptEventFd();

ixwebsocket/IXSelectInterruptPipe.h

@@ -14,7 +14,7 @@
 
 namespace ix
 {
-    class SelectInterruptPipe : public SelectInterrupt {
+    class SelectInterruptPipe final : public SelectInterrupt {
     public:
         SelectInterruptPipe();
         virtual ~SelectInterruptPipe();

ixwebsocket/IXSocketAppleSSL.h

@@ -16,7 +16,7 @@
 
 namespace ix
 {
-    class SocketAppleSSL : public Socket
+    class SocketAppleSSL final : public Socket
     {
     public:
         SocketAppleSSL(int fd = -1);

ixwebsocket/IXSocketOpenSSL.h

@@ -19,7 +19,7 @@
 
 namespace ix
 {
-    class SocketOpenSSL : public Socket
+    class SocketOpenSSL final : public Socket
     {
     public:
         SocketOpenSSL(int fd = -1);

ixwebsocket/IXSocketSChannel.h

@@ -10,7 +10,7 @@
 
 namespace ix
 {
-    class SocketSChannel : public Socket
+    class SocketSChannel final : public Socket
     {
     public:
         SocketSChannel();

ixwebsocket/IXWebSocketServer.h

@@ -23,7 +23,7 @@ namespace ix
     using OnConnectionCallback = std::function<void(std::shared_ptr<WebSocket>,
                                                     std::shared_ptr<ConnectionState>)>;
 
-    class WebSocketServer : public SocketServer {
+    class WebSocketServer final : public SocketServer {
     public:
         WebSocketServer(int port = SocketServer::kDefaultPort,
                         const std::string& host = SocketServer::kDefaultHost,