stateful.h

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/*
    Copyright (C) 2000-2010 Paul Davis 

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef __pbd_stateful_h__
#define __pbd_stateful_h__

#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 (void) = 0;
        virtual int set_state (const XMLNode&, int version) = 0;

        virtual bool apply_changes (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 ();

        /* history management */

        void clear_changes ();
        virtual void clear_owned_changes ();
        PropertyList* get_changes_as_properties (Command *) const;
        virtual void rdiff (std::vector<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 g_atomic_int_get (const_cast<gint*>(&_stateful_frozen)) > 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 &);

        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&) { }

  private:
        PBD::ID  _id;
        gint     _stateful_frozen;
};

} // namespace PBD

#endif /* __pbd_stateful_h__ */