vgtl_visitor.h

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// Visitor implementation -*- C++ -*-

// $Id: vgtl_visitor.h 347 2008-02-06 15:20:01Z schilly $
// Copyright (C) 2001-2003 Hermann Schichl
//
// This file is part of the Vienna Graph Template Library.  This library
// is free software; you can redistribute it and/or modify it under the
// terms of the Library GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library 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
// Library GNU General Public License for more details.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the Library GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the Library GNU General Public License.

#ifndef __VGTL_VISITOR_H
#define __VGTL_VISITOR_H

#include <vgtl_helpers.h>

__VGTL_BEGIN_NAMESPACE

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1209
#endif

//
// visitor base class templates
// 


template <class _Node, class _Ret, class _Col = const _Ret&>
class preorder_visitor
{
public:
  typedef _Ret return_value;
  typedef _Col collect_value;

  preorder_visitor() {}
  virtual ~preorder_visitor() {}
  

  virtual void vinit() { return; }
  virtual return_value vvalue() VGTL_PURE_VIRTUAL
  virtual void vcollect(collect_value __r) { return; }


  virtual bool preorder(const _Node& __n) { return true; }
  virtual void collect(const _Node& __n, collect_value __r) { return; }
  virtual return_value value() VGTL_PURE_VIRTUAL
};


template <class _Node, class _Ret, class _Col = const _Ret&>
class postorder_visitor
{
public:
  typedef _Ret return_value;
  typedef _Col collect_value;

  postorder_visitor() {}
  virtual ~postorder_visitor() {}
  

  virtual void vinit() { return; }
  virtual return_value vvalue() VGTL_PURE_VIRTUAL
  virtual void vcollect(collect_value __r) { return; }


  virtual void init() { return; }
  virtual bool postorder(const _Node& __n) { return false; }
  virtual void collect(const _Node& __n, collect_value __r) { return; }
  virtual return_value value() VGTL_PURE_VIRTUAL
};


template <class _Node, class _Ret, class _Col = const _Ret&>
class prepost_visitor
{
public:
  typedef _Ret return_value;
  typedef _Col collect_value;

  prepost_visitor() {}
  virtual ~prepost_visitor() {}
  

  virtual void vinit() { return; }
  virtual return_value vvalue() VGTL_PURE_VIRTUAL
  virtual void vcollect(collect_value __r) { return; }


  virtual bool preorder(const _Node& __n) { return true; }
  virtual bool postorder(const _Node& __n) { return false; }
  virtual void collect(const _Node& __n, collect_value __r) { return; }
  virtual return_value value() VGTL_PURE_VIRTUAL
};

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma reset woff 1209
#endif

__VGTL_END_NAMESPACE

#endif /* __VGTL_VISITOR_H */

// Local Variables:
// mode:C++
// End:

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