Issue #15 Classes for sharing a single value object,

built on top of the lower level API

src/blackmisc/sharedstate/scalarobserver.cpp

@@ -0,0 +1,46 @@
+/* Copyright (C) 2017
+ * swift Project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution. No part of swift project, including this file, may be copied, modified, propagated,
+ * or distributed except according to the terms contained in the LICENSE file.
+ */
+
+//! \file
+
+#include "blackmisc/sharedstate/scalarobserver.h"
+#include "blackmisc/sharedstate/datalink.h"
+
+namespace BlackMisc
+{
+    namespace SharedState
+    {
+        void CGenericScalarObserver::initialize(IDataLink *dataLink)
+        {
+            dataLink->subscribe(m_observer.data());
+            m_observer->setEventSubscription(CVariant::from(CAnyMatch()));
+            connect(dataLink->watcher(), &CDataLinkConnectionWatcher::connected, this, &CGenericScalarObserver::reconstruct);
+            if (dataLink->watcher()->isConnected()) { reconstruct(); }
+        }
+
+        void CGenericScalarObserver::reconstruct()
+        {
+            m_observer->requestAsync({}, [this](const CVariant &value) { handleEvent(value); });
+        }
+
+        CVariant CGenericScalarObserver::value() const
+        {
+            QMutexLocker lock(&m_valueMutex);
+            return m_value;
+        }
+
+        void CGenericScalarObserver::handleEvent(const CVariant &param)
+        {
+            QMutexLocker lock(&m_valueMutex);
+            if (m_value == param) { return; }
+            m_value = param;
+            lock.unlock();
+            onGenericValueChanged(param);
+        }
+    }
+}