ADDED: A new IPC API based on protobuf and nng

Details, documentation, and language bindings are works in
progress and will be evolving over the course of KiCad 9
development.

include/api/api_server.h

@@ -0,0 +1,97 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2023 Jon Evans <[email protected]>
+ * Copyright (C) 2023 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program 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 program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KICAD_API_SERVER_H
+#define KICAD_API_SERVER_H
+
+#include <memory>
+#include <set>
+#include <string>
+
+#include <wx/event.h>
+#include <wx/filename.h>
+
+class API_HANDLER;
+class API_HANDLER_COMMON;
+class KINNG_REQUEST_SERVER;
+class wxEvtHandler;
+
+
+wxDECLARE_EVENT( API_REQUEST_EVENT, wxCommandEvent );
+
+
+class KICAD_API_SERVER : public wxEvtHandler
+{
+public:
+    KICAD_API_SERVER();
+
+    ~KICAD_API_SERVER();
+
+    /**
+     * Adds a new request handler to the server.  Each handler maintains its own list of API
+     * messages that it knows how to handle, and the server will pass every incoming message to all
+     * handlers in succession until one of them handles it.
+     *
+     * The caller is responsible for the lifetime of the handler and must call DeregisterHandler
+     * before the pointer is freed.
+     *
+     * @param aHandler is a pointer (non-owned) to API_HANDLER
+     */
+    void RegisterHandler( API_HANDLER* aHandler );
+
+    void DeregisterHandler( API_HANDLER* aHandler );
+
+    void SetReadyToReply( bool aReady = true ) { m_readyToReply = aReady; }
+
+private:
+
+    /**
+     * Callback that executes on the server thread and generates an event that will be handled by
+     * the wxWidgets event loop to process an incoming request.  Temporarily takes ownership of the
+     * request pointer so that it can be passed through the event system.
+     *
+     * @param aRequest is a pointer to a string containing bytes that came in over the wire
+     */
+    void onApiRequest( std::string* aRequest );
+
+    /**
+     * Event handler that receives the event on the main thread sent by onApiRequest
+     * @param aEvent will contain a pointer to an incoming API request string in the client data
+     */
+    void handleApiEvent( wxCommandEvent& aEvent );
+
+    void log( const std::string& aOutput );
+
+    std::unique_ptr<KINNG_REQUEST_SERVER> m_server;
+
+    std::set<API_HANDLER*> m_handlers;
+
+    std::string m_token;
+
+    bool m_readyToReply;
+
+    std::unique_ptr<API_HANDLER_COMMON> m_commonHandler;
+
+    static wxString s_logFileName;
+
+    wxFileName m_logFilePath;
+};
+
+#endif //KICAD_API_SERVER_H