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/* $Id: delta.hpp,v 1.5 2006/11/05 04:42:43 ganzhorn Exp $
* This file is part of lfhex.
* Copyright (C) 2006 Salem Ganzhorn <eyekode@yahoo.com>
*
* 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 version 2.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef _DELTA_MAP_
#define _DELTA_MAP_
#include <sys/types.h>
#include <list>
#include <map>
#include <vector>
#include <stack>
#include <iostream>
#include "local.h"
class Delta {
public:
Delta( off_t i, const vector<uchar>& oldData, const vector<uchar>& newData) :
_offset(i), _old(oldData), _new(newData) {}
void setNewData( const vector<uchar>& ndata ) { _new = ndata; }
off_t offset() const { return _offset; }
const vector<uchar>& newData() const { return _new;}
const vector<uchar>& oldData() const { return _old;}
protected:
off_t _offset;
vector<uchar> _old;
vector<uchar> _new;
};
// allocation for all delta's is dynamic, but it is all handled
// within the class.
// the user of the class does not need to worry about memory
// allocation/deallocation.
class DeltaMap {
public:
DeltaMap();
~DeltaMap();
public:
// insert a new delta
size_t insert(off_t offset,
const vector<uchar>& oldData,
const vector<uchar>& newData);
// return the offset of the last inserted Delta.
off_t lastOffset() const;
// set the last delta's newData to data
void setLastData( const vector<uchar>& data);
int numEdits() const { return _undo.size(); }
// find the most recent delta
const Delta* search(off_t offset) const;
// cleans undo/redo stacks and frees memory for all deltas.
// Makes references to delta's invalid.
void clear();
bool undo(); //undo last insert
bool redo(); //redo last insert
// method for iterating over all of the modifications
// finds the first offset that is is not less than lb
// so lower_bound(0) returns the offset of the first delta
// (off_t) -1 is returned on failure
off_t lower_bound(off_t lb) const;
protected:
typedef map<off_t,list<Delta*> > delta_map_t;
// notes:
// the back of the delta list is always the most recent/non undone delta.
map<off_t,list<Delta*> > _map;
stack<Delta*> _undo;
stack<Delta*> _redo;
};
#endif
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