Implement signal handler

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/CMakeLists.txt

@@ -47,6 +47,8 @@ set( PROJECT_FILES
     cafNotificationCenter.cpp
     cafNotificationCenter.h
 
+    cafSignal.h
+
     cafTristate.cpp
     cafTristate.h
     cafFilePath.cpp

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmObjectHandle.h

@@ -2,7 +2,7 @@
 
 #include "cafAssert.h"
 #include "cafPdmBase.h"
-#include "cafSignalHandle.h"
+#include "cafSignal.h"
 
 #include <QString>
 
@@ -20,7 +20,7 @@ class PdmChildArrayFieldHandle;
 //==================================================================================================
 /// The base class of all objects
 //==================================================================================================
-class PdmObjectHandle : public SignalObserver
+class PdmObjectHandle : public SignalObserver, public SignalEmitter
 {
 public:
     PdmObjectHandle();

Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafSignal.h

@@ -0,0 +1,106 @@
+//##################################################################################################
+//
+//   Custom Visualization Core library
+//   Copyright (C) 2020- Ceetron Solutions AS
+//
+//   This library may be used under the terms of either the GNU General Public License or
+//   the GNU Lesser General Public License as follows:
+//
+//   GNU General Public License Usage
+//   This library is free software: you can redistribute it and/or modify
+//   it under the terms of the GNU General Public License as published by
+//   the Free Software Foundation, either version 3 of the License, or
+//   (at your option) any later version.
+//
+//   This 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 General Public License at <<http://www.gnu.org/licenses/gpl.html>>
+//   for more details.
+//
+//   GNU Lesser General Public License Usage
+//   This 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 2.1 of the License, or
+//   (at your option) any later version.
+//
+//   This 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 at <<http://www.gnu.org/licenses/lgpl-2.1.html>>
+//   for more details.
+//
+//##################################################################################################
+#pragma once
+
+#include "cafAssert.h"
+
+#include <functional>
+#include <map>
+#include <string>
+#include <type_traits>
+
+namespace caf
+{
+class SignalObserver
+{
+public:
+    virtual ~SignalObserver() = default;
+};
+
+class SignalEmitter
+{
+public:
+    virtual ~SignalEmitter() = default;
+};
+
+//==================================================================================================
+/// General signal class.
+/// Connect any member function with the signature void(const Signal*, const SignalData* data)
+/// Connect with .connect(this, &Class::nameOfMethod)
+/// The method should accept that data may be nullptr
+//==================================================================================================
+template <typename... Args>
+class Signal
+{
+public:
+    using MemberCallback = std::function<void( const SignalEmitter*, Args... args )>;
+
+public:
+    Signal( const SignalEmitter* emitter )
+        : m_emitter( emitter )
+    {
+    }
+    virtual ~Signal() = default;
+
+    template <typename ClassType>
+    void connect( ClassType* observer, void ( ClassType::*method )( const SignalEmitter*, Args... args ) )
+    {
+        static_assert( std::is_convertible<ClassType*, SignalObserver*>::value,
+                       "Only classes that inherit SignalObserver can connect as an observer of a Signal." );
+        MemberCallback lambda = [=]( const SignalEmitter* emitter, Args... args ) {
+            // Call method
+            ( observer->*method )( emitter, args... );
+        };
+        m_observerCallbacks[observer] = lambda;
+    }
+
+    void disconnect( SignalObserver* observer ) { m_observerCallbacks.erase( observer ); }
+    void send( Args... args )
+    {
+        for ( auto observerCallbackPair : m_observerCallbacks )
+        {
+            observerCallbackPair.second( m_emitter, args... );
+        }
+    }
+
+private:
+    Signal( const Signal& rhs ) = default;
+    Signal& operator=( const Signal& rhs ) = default;
+
+    std::map<SignalObserver*, MemberCallback> m_observerCallbacks;
+    const SignalEmitter*                      m_emitter;
+};
+} // namespace caf