Add CppCon2018 chat server example and video

example/cppcon2018/shared_state.cpp

@@ -0,0 +1,41 @@
+//
+// Copyright (c) 2018 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/vinniefalco/CppCon2018
+//
+
+#include "shared_state.hpp"
+#include "websocket_session.hpp"
+
+shared_state::
+shared_state(std::string doc_root)
+    : doc_root_(std::move(doc_root))
+{
+}
+
+void
+shared_state::
+join(websocket_session& session)
+{
+    sessions_.insert(&session);
+}
+
+void
+shared_state::
+leave(websocket_session& session)
+{
+    sessions_.erase(&session);
+}
+
+void
+shared_state::
+send(std::string message)
+{
+    auto const ss = std::make_shared<std::string const>(std::move(message));
+
+    for(auto session : sessions_)
+        session->send(ss);
+}