tag.h

一个类似STL的自动机的源代码库

/*
 * ASTL - the Automaton Standard Template Library.
 * C++ generic components for Finite State Automata handling.
 * Copyright (C) 2000-2003 Vincent Le Maout ([e-mail]).
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, 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 GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#ifndef ASTL_TAG_H
#define ASTL_TAG_H

// This file defines the default tag type "empty_tag"

#include <iostream>

ASTL_BEGIN_NAMESPACE

struct empty_tag {};
bool operator==(const empty_tag&, const empty_tag&) {
  return true;
}
bool operator<(const empty_tag&, const empty_tag&) {
  return false;
}
ostream& operator<<(ostream &out, const empty_tag&) {
  return out;
}
istream& operator>>(istream &in, empty_tag&) {
  return in;
}

#ifdef __GNUG__
// Specialized type_traits for empty_tag
struct __type_traits<empty_tag>
{
  typedef __true_type has_trivial_default_constructor;
  typedef __true_type has_trivial_copy_constructor;
  typedef __true_type has_trivial_assignment_operator;
  typedef __true_type has_trivial_destructor;
  typedef __true_type is_POD_type;
};
#endif

ASTL_END_NAMESPACE

#endif // ASTL_TAG_H