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livetrax/libs/pbd/pbd/property_basics.h
Carl Hetherington 390f18c115 Clarify commentary slightly. No functional changes.
git-svn-id: svn://localhost/ardour2/branches/3.0@8345 d708f5d6-7413-0410-9779-e7cbd77b26cf
2010-12-28 03:05:09 +00:00

173 lines
4.8 KiB
C++

/*
Copyright (C) 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 __libpbd_property_basics_h__
#define __libpbd_property_basics_h__
#include <glib.h>
#include <set>
#include <vector>
#include "pbd/xml++.h"
class Command;
namespace PBD {
class PropertyList;
class StatefulDiffCommand;
/** A unique identifier for a property of a Stateful object */
typedef GQuark PropertyID;
template<typename T>
struct PropertyDescriptor {
PropertyDescriptor () : property_id (0) {}
PropertyDescriptor (PropertyID pid) : property_id (pid) {}
PropertyID property_id;
typedef T value_type;
};
/** A list of IDs of Properties that have changed in some situation or other */
class PropertyChange : public std::set<PropertyID>
{
public:
PropertyChange() {}
template<typename T> PropertyChange(PropertyDescriptor<T> p);
PropertyChange(const PropertyChange& other) : std::set<PropertyID> (other) {}
PropertyChange operator=(const PropertyChange& other) {
clear ();
insert (other.begin (), other.end ());
return *this;
}
template<typename T> PropertyChange operator=(PropertyDescriptor<T> p);
template<typename T> bool contains (PropertyDescriptor<T> p) const;
bool contains (const PropertyChange& other) const {
for (const_iterator x = other.begin (); x != other.end (); ++x) {
if (find (*x) != end ()) {
return true;
}
}
return false;
}
void add (PropertyID id) { insert (id); }
void add (const PropertyChange& other) { insert (other.begin (), other.end ()); }
template<typename T> void add (PropertyDescriptor<T> p);
};
/** Base (non template) part of Property
* Properties are used for two main reasons:
* - to handle current state (when serializing Stateful objects)
* - to handle history since some operation was started (when making StatefulDiffCommands for undo)
*/
class PropertyBase
{
public:
PropertyBase (PropertyID pid)
: _property_id (pid)
{}
virtual ~PropertyBase () {}
/* MANAGEMENT OF Stateful STATE */
/** Set the value of this property from a Stateful node.
* @return true if the value was set.
*/
virtual bool set_value (XMLNode const &) = 0;
/** Get this property's value and put it into a Stateful node */
virtual void get_value (XMLNode& node) const = 0;
/* MANAGEMENT OF HISTORY */
/** Forget about any old changes to this property's value */
virtual void clear_changes () = 0;
/** Tell any things we own to forget about their old values */
virtual void clear_owned_changes () {}
/** @return true if this property has changed in value since construction or since
* the last call to clear_changes (), whichever was more recent.
*/
virtual bool changed () const = 0;
/** Invert the changes in this property */
virtual void invert () = 0;
/* TRANSFERRING HISTORY TO / FROM A StatefulDiffCommand */
/** Get any changes in this property as XML and add them to a
* StatefulDiffCommand node.
*/
virtual void get_changes_as_xml (XMLNode *) const = 0;
/** If this Property has changed, clone it and add it to a given list.
* Used for making StatefulDiffCommands.
*/
virtual void get_changes_as_properties (PropertyList& changes, Command *) const = 0;
/** Collect StatefulDiffCommands for changes to anything that we own */
virtual void rdiff (std::vector<Command*> &) const {}
/** Look in an XML node written by get_changes_as_xml and, if XML from this property
* is found, create a property with the changes from the XML.
*/
virtual PropertyBase* clone_from_xml (const XMLNode &) const { return 0; }
/* VARIOUS */
virtual PropertyBase* clone () const = 0;
/** Set this property's current state from another */
virtual void apply_changes (PropertyBase const *) = 0;
const gchar* property_name () const { return g_quark_to_string (_property_id); }
PropertyID property_id () const { return _property_id; }
bool operator==(PropertyID pid) const {
return _property_id == pid;
}
protected:
/* copy construction only by subclasses */
PropertyBase (PropertyBase const & b)
: _property_id (b._property_id)
{}
private:
PropertyID _property_id;
};
}
#endif /* __libpbd_property_basics_h__ */