Implementation of a generic CallBackList (#5710)

* Initial version

Move to experimental namespace

Change namespace

cores/esp8266/CallBackList.h

@@ -0,0 +1,84 @@
+#ifndef __CALLBACKLIST_H__
+#define __CALLBACKLIST_H__
+
+
+/*
+ CallBackList, An implemention for handling callback execution
+
+ Copyright (c) 2019 Herman Reintke. All rights reserved.
+ This file is part of the esp8266 core for Arduino environment.
+
+ 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 for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <Arduino.h>
+#include <memory>
+#include <list>
+#include <utility>
+
+namespace experimental
+{
+namespace CBListImplentation
+{
+
+template<class cbFunctionT>
+class CallBackList
+{
+public:
+	CallBackList (){};
+
+    struct CallBackInfo
+    {
+		CallBackInfo(cbFunctionT f) : cbFunction(f, true){};
+		CallBackInfo(cbFunctionT f, bool ar) : cbFunction(f), _allowRemove(ar) {};
+		cbFunctionT  cbFunction;
+    	bool _allowRemove = true;
+    	bool allowRemove()
+    	{
+    		return _allowRemove;
+    	}
+     };
+    using CallBackHandler = std::shared_ptr<CallBackInfo> ;
+    std::list<CallBackHandler> callBackEventList;
+
+    CallBackHandler add(cbFunctionT af, bool ad = true) {
+    	CallBackHandler handler = std::make_shared<CallBackInfo>(CallBackInfo(af,ad));
+    	callBackEventList.emplace_back(handler);
+    	return handler;
+    }
+
+    void remove(CallBackHandler& dh) {
+    	callBackEventList.remove(dh);
+	}
+
+    template<typename... Args>
+    void execute(Args... params) {
+        for(auto it = std::begin(callBackEventList); it != std::end(callBackEventList); ) {
+        	CallBackHandler &handler = *it;
+            if (handler->allowRemove() && handler.unique()) {
+                it = callBackEventList.erase(it);
+            }
+            else {
+             	handler->cbFunction(params...);
+                ++it;
+            }
+        }
+    }
+};
+
+} //CBListImplementation
+}//experimental
+
+#endif // __CALLBACKLIST_H__