util: move signal-*.* into util/signal/ directory

refs #3940

Change-Id: I36e3420846959f39bb51a3ce7ef7f03e7c2c22aa
diff --git a/src/util/signal/scoped-connection.cpp b/src/util/signal/scoped-connection.cpp
new file mode 100644
index 0000000..cbbfaba
--- /dev/null
+++ b/src/util/signal/scoped-connection.cpp
@@ -0,0 +1,83 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "scoped-connection.hpp"
+
+namespace ndn {
+namespace util {
+namespace signal {
+
+#if NDN_CXX_HAVE_IS_NOTHROW_MOVE_CONSTRUCTIBLE
+static_assert(std::is_nothrow_move_constructible<ScopedConnection>::value,
+              "ScopedConnection must be MoveConstructible with noexcept");
+#endif // NDN_CXX_HAVE_IS_NOTHROW_MOVE_CONSTRUCTIBLE
+
+ScopedConnection::ScopedConnection()
+{
+}
+
+ScopedConnection::ScopedConnection(const Connection& connection)
+  : m_connection(connection)
+{
+}
+
+ScopedConnection::ScopedConnection(ScopedConnection&& other) noexcept
+  : m_connection(other.m_connection)
+{
+  other.release();
+}
+
+ScopedConnection&
+ScopedConnection::operator=(const Connection& connection)
+{
+  if (m_connection != connection) {
+    m_connection.disconnect();
+    m_connection = connection;
+  }
+  return *this;
+}
+
+ScopedConnection::~ScopedConnection() noexcept
+{
+  m_connection.disconnect();
+}
+
+void
+ScopedConnection::disconnect()
+{
+  m_connection.disconnect();
+}
+
+bool
+ScopedConnection::isConnected() const
+{
+  return m_connection.isConnected();
+}
+
+void
+ScopedConnection::release()
+{
+  m_connection = {};
+}
+
+} // namespace signal
+} // namespace util
+} // namespace ndn