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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 <cassert>
#include "pbd/id.h"
#include "pbd/xml++.h"
class XMLNode;
namespace PBD {
namespace sys {
class path;
}
/** Base (non template) part of State */
class StateBase
{
public:
StateBase (std::string const & p)
: _have_old (false)
, _xml_property_name (p)
{
}
StateBase (StateBase const & s)
: _have_old (s._have_old)
, _xml_property_name (s._xml_property_name)
{
}
/** Forget about any old value for this state */
void clear_history () {
_have_old = false;
}
virtual void diff (XMLNode *, XMLNode *) const = 0;
protected:
bool _have_old;
std::string _xml_property_name;
};
/** Class to represent a single piece of state in a Stateful object */
template <class T>
class State : public StateBase
{
public:
State (std::string const & p, T const & v)
: StateBase (p)
, _current (v)
{
}
State (State<T> const & s)
: StateBase (s)
{
_current = s._current;
_old = s._old;
}
State<T> & operator= (State<T> const & s) {
/* XXX: isn't there a nicer place to do this? */
_have_old = s._have_old;
_xml_property_name = s._xml_property_name;
_current = s._current;
_old = s._old;
return *this;
}
T & operator= (T const & v) {
set (v);
return _current;
}
T & operator+= (T const & v) {
set (_current + v);
return _current;
}
operator T () const {
return _current;
}
T const & get () const {
return _current;
}
void diff (XMLNode* old, XMLNode* current) const {
if (_have_old) {
std::stringstream o;
o << _old;
old->add_property (_xml_property_name.c_str(), o.str().c_str());
std::stringstream c;
c << _current;
current->add_property (_xml_property_name.c_str(), c.str().c_str());
}
}
private:
void set (T const & v) {
_old = _current;
_have_old = true;
_current = v;
}
T _current;
T _old;
};
/** Base class for objects with saveable and undoable state */
class Stateful {
public:
Stateful ();
virtual ~Stateful();
virtual XMLNode& get_state (void) = 0;
virtual int set_state (const XMLNode&, int version) = 0;
void add_state (StateBase & s) {
_states.push_back (&s);
}
/* Extra XML nodes */
void add_extra_xml (XMLNode&);
XMLNode *extra_xml (const std::string& str);
const PBD::ID& id() const { return _id; }
void clear_history ();
std::pair<XMLNode *, XMLNode*> diff ();
static int current_state_version;
static int loading_state_version;
protected:
void add_instant_xml (XMLNode&, const sys::path& directory_path);
XMLNode *instant_xml (const std::string& str, const sys::path& directory_path);
XMLNode *_extra_xml;
XMLNode *_instant_xml;
PBD::ID _id;
std::string _xml_node_name; ///< name of node to use for this object in XML
std::list<StateBase*> _states; ///< state variables that this object has
};
} // namespace PBD
#endif /* __pbd_stateful_h__ */
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