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[ric-plt/xapp-frame-cpp.git] / src / messaging / msg_component.hpp

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+// vi: ts=4 sw=4 noet:
+/*
+==================================================================================
+       Copyright (c) 2020 Nokia
+       Copyright (c) 2020 AT&T Intellectual Property.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================================
+*/
+
+/*
+       Mnemonic:       msg_component.hpp
+       Abstract:       Defines a message component type which is needed in order
+                               to use smart pointers (unique) to point at bytes in the
+                               RMR message (which are not directly allocated and cannot
+                               be freed/deleted outside of RMR (require a special destruction
+                               call in the smart pointer).
+
+       Date:           17 March 2020
+       Author:         E. Scott Daniels
+*/
+
+#ifndef _MSG_COMPONENT_HPP
+#define _MSG_COMPONENT_HPP
+
+#include <memory>
+
+//  -------------- smart pointer support  --------------------------------
+/*
+       Pointers to a lot of things in the RMR message aren't directly
+       allocated and thus cannot be directly freed. To return a smart
+       pointer to these we have to ensure that no attempt to free/delete
+       the reference is made.  This struct defines a type with a function
+       pointer (operator) that is 'registered' as the delete function for
+       such a smart pointer, and does _nothing_ when called.
+*/
+typedef struct {
+       void operator()( unsigned char * p ){}
+} unfreeable;
+
+/*
+       A 'generic' smart pointer to a component in the message which cannot
+       be directly freed (e.g. the payload, meid, etc).
+*/
+using Msg_component = std::unique_ptr<unsigned char, unfreeable>;
+
+#endif