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

refs #3940

Change-Id: I36e3420846959f39bb51a3ce7ef7f03e7c2c22aa
diff --git a/src/util/signal/connection.cpp b/src/util/signal/connection.cpp
new file mode 100644
index 0000000..7d46eb1
--- /dev/null
+++ b/src/util/signal/connection.cpp
@@ -0,0 +1,70 @@
+/* -*- 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 "connection.hpp"
+
+namespace ndn {
+namespace util {
+namespace signal {
+
+BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Connection>));
+
+Connection::Connection()
+{
+}
+
+Connection::Connection(weak_ptr<function<void()>> disconnect)
+  : m_disconnect(disconnect)
+{
+}
+
+void
+Connection::disconnect()
+{
+  shared_ptr<function<void()>> f = m_disconnect.lock();
+  if (f != nullptr) {
+    (*f)();
+  }
+}
+
+bool
+Connection::isConnected() const
+{
+  return !m_disconnect.expired();
+}
+
+bool
+Connection::operator==(const Connection& other) const
+{
+  shared_ptr<function<void()>> f1 = m_disconnect.lock();
+  shared_ptr<function<void()>> f2 = other.m_disconnect.lock();
+  return f1 == f2;
+}
+
+bool
+Connection::operator!=(const Connection& other) const
+{
+  return !(this->operator==(other));
+}
+
+} // namespace signal
+} // namespace util
+} // namespace ndn