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/* -*- Mode:C++ -*- */
/*
* change_tracking.hh
* Copyright (C) 1999 by John Heidemann
* $Id: change_tracking.hh,v 1.9 1999/09/06 18:16:16 johnh Exp $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* 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.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifndef lavaps_change_tracking_h
#define lavaps_change_tracking_h
template <class T>
class change_tracking {
protected:
T last_;
T change_;
public:
// gcc won't accept :last_(0)
// with error ``only constructors take base initializers''
change_tracking() { last_ = (T)0; } // xxx: should track whether we're init'ed
change_tracking(T first) { change_ = last_ = first; } // the last should be first
void tick_set(T current) { change_ = T(current - last_); last_ = current; }
void tick_incr(T delta) { change_ = delta; last_ += delta; }
void clear_change() { change_ = (T)0; }
T last() { return last_; }
T change() { return change_; }
bool changed() { return change_ != 0; }
};
template <class T, class SUM>
class sum_change_tracking : public change_tracking<T> {
protected:
static SUM s_;
void update_sum() { s_.sum_ += change_; }
public:
sum_change_tracking() {};
sum_change_tracking(T first) : change_tracking<T>(first) { update_sum(frst); };
~sum_change_tracking() { tick_incr(-last_); };
void tick_set(T current) { change_tracking<T>::tick_set(current); update_sum(); };
void tick_incr(T delta) { change_tracking<T>::tick_incr(delta); update_sum(); };
T sum() { return s_.sum_; }
};
#endif /* lavaps_change_tracking_h */
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