state_label_empty.h

Go to the documentation of this file.

// Author(s): Jan Friso Groote
// Copyright: see the accompanying file COPYING or copy at
// https://github.com/mCRL2org/mCRL2/blob/master/COPYING
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
 
#ifndef MCRL2_LTS_STATE_LABEL_EMPTY_H
#define MCRL2_LTS_STATE_LABEL_EMPTY_H
 
#include <string>
 
namespace mcrl2
{
namespace lts
{
 
class state_label_empty
{
  public:
 
    /* \brief Equality on empty state labels. Always returns true.
    */
    bool operator ==(const state_label_empty&) const
    {
      return true;
    }
 
    /* \brief Non equality on empty state labels. Always returns false.
    */
    bool operator !=(const state_label_empty& other) const
    {
      return !(*this==other);
    }
 
    state_label_empty operator+(const state_label_empty& ) const
    {
      return state_label_empty();
    }
 
    static state_label_empty number_to_label(const std::size_t )
    {
      return state_label_empty();
    }
};
 
inline std::string pp(const state_label_empty& )
{
  return "empty";
}
 
 
} // namespace lts
} // namespace mcrl2
 
#endif