85 lines
2.8 KiB
C++
85 lines
2.8 KiB
C++
// Filename: updateSeq.h
|
|
// Created by: drose (30Sep99)
|
|
//
|
|
////////////////////////////////////////////////////////////////////
|
|
//
|
|
// PANDA 3D SOFTWARE
|
|
// Copyright (c) 2001 - 2004, Disney Enterprises, Inc. All rights reserved
|
|
//
|
|
// All use of this software is subject to the terms of the Panda 3d
|
|
// Software license. You should have received a copy of this license
|
|
// along with this source code; you will also find a current copy of
|
|
// the license at http://etc.cmu.edu/panda3d/docs/license/ .
|
|
//
|
|
// To contact the maintainers of this program write to
|
|
// panda3d-general@lists.sourceforge.net .
|
|
//
|
|
////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef UPDATE_SEQ
|
|
#define UPDATE_SEQ
|
|
|
|
#include "pandabase.h"
|
|
|
|
////////////////////////////////////////////////////////////////////
|
|
// Class : UpdateSeq
|
|
// Description : This is a sequence number that increments
|
|
// monotonically. It can be used to track cache
|
|
// updates, or serve as a kind of timestamp for any
|
|
// changing properties.
|
|
//
|
|
// A special class is used instead of simply an int, so
|
|
// we can elegantly handle such things as wraparound and
|
|
// special cases. There are two special cases.
|
|
// Firstly, a sequence number is 'initial' when it is
|
|
// first created. This sequence is older than any other
|
|
// sequence number. Secondly, a sequence number may be
|
|
// explicitly set to 'old'. This is older than any
|
|
// other sequence number except 'initial'. Finally, we
|
|
// have the explicit number 'fresh', which is newer
|
|
// than any other sequence number. All other sequences
|
|
// are numeric and are monotonically increasing.
|
|
////////////////////////////////////////////////////////////////////
|
|
class EXPCL_PANDA UpdateSeq {
|
|
PUBLISHED:
|
|
INLINE UpdateSeq();
|
|
INLINE static UpdateSeq initial();
|
|
INLINE static UpdateSeq old();
|
|
INLINE static UpdateSeq fresh();
|
|
|
|
INLINE UpdateSeq(const UpdateSeq ©);
|
|
INLINE UpdateSeq &operator = (const UpdateSeq ©);
|
|
|
|
INLINE void clear();
|
|
|
|
INLINE bool is_initial() const;
|
|
INLINE bool is_old() const;
|
|
INLINE bool is_fresh() const;
|
|
INLINE bool is_special() const;
|
|
|
|
INLINE bool operator == (const UpdateSeq &other) const;
|
|
INLINE bool operator != (const UpdateSeq &other) const;
|
|
INLINE bool operator < (const UpdateSeq &other) const;
|
|
INLINE bool operator <= (const UpdateSeq &other) const;
|
|
|
|
INLINE UpdateSeq operator ++ ();
|
|
INLINE UpdateSeq operator ++ (int);
|
|
|
|
INLINE void output(ostream &out) const;
|
|
|
|
private:
|
|
enum SpecialCases {
|
|
SC_initial = 0,
|
|
SC_old = 1,
|
|
SC_fresh = ~0,
|
|
};
|
|
|
|
unsigned int _seq;
|
|
};
|
|
|
|
INLINE ostream &operator << (ostream &out, const UpdateSeq &value);
|
|
|
|
#include "updateSeq.I"
|
|
|
|
#endif
|