stateful.h

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/*
 * Copyright (C) 2000-2015 Paul Davis <paul@linuxaudiosystems.com>
 * Copyright (C) 2006 Hans Fugal <hans@fugal.net>
 * Copyright (C) 2007-2015 Tim Mayberry <mojofunk@gmail.com>
 * Copyright (C) 2009-2011 Carl Hetherington <carl@carlh.net>
 * Copyright (C) 2015 Robin Gareus <robin@gareus.org>
 *
 * 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 2 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#ifndef __pbd_stateful_h__
#define __pbd_stateful_h__
 
#include <atomic>
#include <string>
#include <list>
#include <cassert>
 
#include "pbd/libpbd_visibility.h"
#include "pbd/id.h"
#include "pbd/xml++.h"
#include "pbd/property_basics.h"
#include "pbd/signals.h"
 
class XMLNode;
 
namespace PBD {
 
namespace sys {
        class path;
}
 
class PropertyList;
class OwnedPropertyList;
 
class LIBPBD_API Stateful {
  public:
        Stateful ();
        virtual ~Stateful();
 
        virtual XMLNode& get_state () const = 0;
        virtual int set_state (const XMLNode&, int version) = 0;
 
        virtual bool apply_change (PropertyBase const &);
        PropertyChange apply_changes (PropertyList const &);
 
        const OwnedPropertyList& properties() const { return *_properties; }
 
        void add_property (PropertyBase& s);
 
        /* Extra XML node: so that 3rd parties can attach state to the XMLNode
           representing the state of this object.
         */
 
        void add_extra_xml (XMLNode&);
        XMLNode *extra_xml (const std::string& str, bool add_if_missing = false);
        void save_extra_xml (const XMLNode&);
 
        const PBD::ID& id() const { return _id; }
        bool set_id (const XMLNode&);
        void set_id (const std::string&);
        void reset_id ();
 
        /* RAII structure to manage thread-local ID regeneration.
         */
        struct ForceIDRegeneration {
                ForceIDRegeneration () {
                        set_regenerate_xml_and_string_ids_in_this_thread (true);
                }
                ~ForceIDRegeneration () {
                        set_regenerate_xml_and_string_ids_in_this_thread (false);
                }
        };
 
        /* history management */
 
        void clear_changes ();
        virtual void clear_owned_changes ();
        PropertyList* get_changes_as_properties (PBD::Command *) const;
        virtual void rdiff (std::vector<PBD::Command*> &) const;
        bool changed() const;
 
        /* create a property list from an XMLNode */
        virtual PropertyList* property_factory (const XMLNode&) const;
 
        /* How stateful's notify of changes to their properties */
        PBD::Signal1<void,const PropertyChange&> PropertyChanged;
 
        static int current_state_version;
        static int loading_state_version;
 
        virtual void suspend_property_changes ();
        virtual void resume_property_changes ();
 
        bool property_changes_suspended() const { return _stateful_frozen.load() > 0; }
 
  protected:
 
        void add_instant_xml (XMLNode&, const std::string& directory_path);
        XMLNode *instant_xml (const std::string& str, const std::string& directory_path);
        void add_properties (XMLNode &) const;
 
        PropertyChange set_values (XMLNode const &);
 
        /* derived classes can implement this to do cross-checking
           of property values after either a PropertyList or XML
           driven property change.
        */
        virtual void post_set (const PropertyChange&) { };
 
        XMLNode *_extra_xml;
        XMLNode *_instant_xml;
        PBD::PropertyChange     _pending_changed;
        Glib::Threads::Mutex _lock;
 
        std::string _xml_node_name; 
        OwnedPropertyList* _properties;
 
        virtual void send_change (const PropertyChange&);
        virtual void mid_thaw (const PropertyChange&) { }
 
        bool regenerate_xml_or_string_ids () const;
 
  private:
        friend struct ForceIDRegeneration;
        static Glib::Threads::Private<bool> _regenerate_xml_or_string_ids;
 
        PBD::ID           _id;
        std::atomic<int> _stateful_frozen;
 
        static void set_regenerate_xml_and_string_ids_in_this_thread (bool yn);
};
 
} // namespace PBD
 
#endif /* __pbd_stateful_h__ */