refactor: Prepare deprecation of non-namespaced types and headers

fairmq/Message.h

@@ -9,6 +9,71 @@
 #ifndef FAIR_MQ_MESSAGE_H
 #define FAIR_MQ_MESSAGE_H
 
-#include <FairMQMessage.h>
+#include <cstddef>   // for size_t
+#include <fairmq/Transports.h>
+#include <memory>   // unique_ptr
+#include <stdexcept>
+
+namespace fair::mq {
+
+using FreeFn = void(void* data, void* hint);
+class TransportFactory;
+
+struct Alignment
+{
+    size_t alignment;
+    explicit operator size_t() const { return alignment; }
+};
+
+struct Message
+{
+    Message() = default;
+    Message(TransportFactory* factory)
+        : fTransport(factory)
+    {}
+
+    virtual void Rebuild() = 0;
+    virtual void Rebuild(Alignment alignment) = 0;
+    virtual void Rebuild(const size_t size) = 0;
+    virtual void Rebuild(const size_t size, Alignment alignment) = 0;
+    virtual void Rebuild(void* data, const size_t size, FreeFn* ffn, void* hint = nullptr) = 0;
+
+    virtual void* GetData() const = 0;
+    virtual size_t GetSize() const = 0;
+
+    virtual bool SetUsedSize(const size_t size) = 0;
+
+    virtual Transport GetType() const = 0;
+    TransportFactory* GetTransport() { return fTransport; }
+    void SetTransport(TransportFactory* transport) { fTransport = transport; }
+
+    virtual void Copy(const Message& msg) = 0;
+
+    virtual ~Message() = default;
+
+  private:
+    TransportFactory* fTransport{nullptr};
+};
+
+using MessagePtr = std::unique_ptr<Message>;
+
+struct MessageError : std::runtime_error
+{
+    using std::runtime_error::runtime_error;
+};
+
+struct MessageBadAlloc : std::runtime_error
+{
+    using std::runtime_error::runtime_error;
+};
+
+}   // namespace fair::mq
+
+// using fairmq_free_fn [[deprecated("Use fair::mq::FreeFn")]] = fair::mq::FreeFn;
+// using FairMQMessage [[deprecated("Use fair::mq::Message")]] = fair::mq::Message;
+// using FairMQMessagePtr [[deprecated("Use fair::mq::MessagePtr")]] = fair::mq::MessagePtr;
+using fairmq_free_fn = fair::mq::FreeFn;
+using FairMQMessage = fair::mq::Message;
+using FairMQMessagePtr = fair::mq::MessagePtr;
 
 #endif   // FAIR_MQ_MESSAGE_H