util: scheduler::ScopedEventId to automatically cancel scheduled events upon destruction

Change-Id: I3254983ab27480143c778baa28de7eb0409b26ce
Refs: #2442
diff --git a/src/util/scheduler-scoped-event-id.cpp b/src/util/scheduler-scoped-event-id.cpp
new file mode 100644
index 0000000..c69af3b
--- /dev/null
+++ b/src/util/scheduler-scoped-event-id.cpp
@@ -0,0 +1,69 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2015 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 "scheduler-scoped-event-id.hpp"
+
+namespace ndn {
+namespace util {
+namespace scheduler {
+
+ScopedEventId::ScopedEventId(Scheduler& scheduler)
+  : m_scheduler(&scheduler)
+{
+}
+
+ScopedEventId::ScopedEventId(ScopedEventId&& other)
+  : m_scheduler(other.m_scheduler)
+  , m_event(other.m_event)
+{
+  other.release();
+}
+
+ScopedEventId&
+ScopedEventId::operator=(const EventId& event)
+{
+  if (m_event != event) {
+    m_scheduler->cancelEvent(m_event);
+    m_event = event;
+  }
+  return *this;
+}
+
+ScopedEventId::~ScopedEventId()
+{
+  m_scheduler->cancelEvent(m_event);
+}
+
+void
+ScopedEventId::cancel()
+{
+  m_scheduler->cancelEvent(m_event);
+}
+
+void
+ScopedEventId::release()
+{
+  m_event.reset();
+}
+
+} // namespace scheduler
+} // namespace util
+} // namespace ndn