unique_id.h

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#ifndef UNIQUE_ID_CLASS
#define UNIQUE_ID_CLASS
 
/*****************************************************************************\
*                                                                             *
*  Name   : unique_id                                                         *
*  Author : Chris Koeritz                                                     *
*                                                                             *
*******************************************************************************
* Copyright (c) 1999-$now By Author.  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; either version 2 of   *
* the License or (at your option) any later version.  This is online at:      *
*     http://www.fsf.org/copyleft/gpl.html                                    *
* Please send any updates to: fred@gruntose.com                               *
\*****************************************************************************/
 
#include <basis/contracts.h>
 
namespace structures {
 
 
template <class uniquifier>
class unique_id : public virtual basis::equalizable
{
public:
  unique_id(uniquifier initial_value) : _id(initial_value) {}
 
  unique_id(const unique_id<uniquifier> &to_copy) { *this = to_copy; }
 
  ~unique_id() {}
 
  virtual bool equal_to(const equalizable &to_compare) const {
    const unique_id<uniquifier> *cast = dynamic_cast<const unique_id<uniquifier> *>(&to_compare);
    if (!cast) throw "error: unique_id::==: unknown type";
    return cast->_id == _id; 
  }
 
 
  bool operator == (const unique_id<uniquifier> &to_compare) const
          { return _id == to_compare._id; }
 
  unique_id & operator = (const unique_id<uniquifier> &to_copy)
          { if (this != &to_copy) _id = to_copy._id; return *this; }
 
  uniquifier raw_id() const { return _id; }
 
  void set_raw_id(uniquifier new_value) { _id = new_value; }
 
private:
  uniquifier _id;  
};
 
 
 
template <class uniquifier>
class orderable_unique_id : public unique_id<uniquifier>
{
public:
  orderable_unique_id(const uniquifier &initial_value)
          : unique_id<uniquifier>(initial_value) {}
  orderable_unique_id(const unique_id<uniquifier> &initial_value)
          : unique_id<uniquifier>(initial_value) {}
  ~orderable_unique_id() {}
 
  bool operator < (const unique_id<uniquifier> &to_compare) const
          { return this->raw_id() < to_compare.raw_id(); }
};
 
 
 
class unique_int : public unique_id<int>
{
public:
  unique_int(int initial = 0) : unique_id<int>(initial) {}
 
  bool operator ! () const { return raw_id() == 0; }
 
};
 
} //namespace.
 
#endif