// Copyright (c) 1994 James Clark

// See the file COPYING for copying permission.

#ifndef Undo_INCLUDED

#define Undo_INCLUDED 1

#ifdef __GNUG__

#pragma interface

#endif

#include "Link.h"

#include "ContentToken.h"

#include "OpenElement.h"

#include "Allocator.h"

#ifdef SP_NAMESPACE

namespace SP_NAMESPACE {

#endif

class ParserState;

class Event;

class Undo : public Link {

public:

  void *operator new(size_t sz, Allocator &alloc) { return alloc.alloc(sz); }

  void *operator new(size_t sz) { return Allocator::allocSimple(sz); }

  void operator delete(void *p) { Allocator::free(p); }

#ifdef SP_HAVE_PLACEMENT_OPERATOR_DELETE

  void operator delete(void *p, Allocator &) { Allocator::free(p); }

#endif

  Undo();

  virtual ~Undo();

  virtual void undo(ParserState *) = 0;

private:

  Undo(const Undo &);		// undefined

  void operator=(const Undo &);	// undefined

};

class UndoTransition : public Undo {

public:

  UndoTransition(const MatchState &);

  void undo(ParserState *);

private:

  UndoTransition(const UndoTransition &); // undefined

  void operator=(const UndoTransition &); // undefined

  MatchState state_;

};

class UndoStartTag : public Undo {

public:

  UndoStartTag();

  void undo(ParserState *);

private:

  UndoStartTag(const UndoStartTag &); // undefined

  void operator=(const UndoStartTag &);	// undefined

};

class UndoEndTag : public Undo {

public:

  UndoEndTag(OpenElement *);

  void undo(ParserState *);

private:

  UndoEndTag(const UndoEndTag &); // undefined

  void operator=(const UndoEndTag &); // undefined

  Owner<OpenElement> element_;

};

#ifdef SP_NAMESPACE

}

#endif

#endif /* not Undo_INCLUDED */