/* -*- C++ -*-
 * lemon/bits/extended_pair.h - Part of LEMON, a generic C++ optimization library
 *
 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
 * (Egervary Research Group on Combinatorial Optimization, EGRES).
 *
 * Permission to use, modify and distribute this software is granted
 * provided that this copyright notice appears in all copies. For
 * precise terms see the accompanying LICENSE file.
 *
 * This software is provided "AS IS" with no warranty of any kind,
 * express or implied, and with no claim as to its suitability for any
 * purpose.
 *
 */

#ifndef LEMON_EXTENDED_PAIR_H
#define LEMON_EXTENDED_PAIR_H

///\ingroup misc
///\file
///\brief A more customizable pair type than std::pair.

namespace lemon {
  
  /// \brief A more customizable pair type than std::pair.
  ///
  /// This type is a customizable pair type. The main goal
  /// is that the constructor's parameter type does not depend
  /// on the stored data type. This way it is possible to store
  /// references in the extended_pair.
  /// \code
  /// int a; char b;
  /// typedef extended_pair<int&, int&, char&, char&> ICPair;
  /// ICPair p(a, b); 
  /// // like a real reference to an std::pair<int, char>
  /// // but the pair does not exist
  /// p.first = 42;
  /// p.second = '@';
  /// \endcode
  /// \param T1 The type of first.
  /// \param A1 The parameter type for first.
  /// \param T2 The type of second.
  /// \param A2 The parameter type for second.
  template <typename T1, typename A1, typename T2, typename A2>
  struct extended_pair {
    /// \brief The type of first.
    ///
    /// The type of first.
    typedef T1 first_type;
    /// \brief The type of second.
    ///
    /// The type of second.
    typedef T2 second_type;

    /// \brief Default constructor.
    ///
    /// Default constructor. It calls the default constructor of
    /// first and second.
    extended_pair() : first(), second() {}

    /// \brief Constructor.
    ///
    /// Constructor. 
    extended_pair(A1 f, A2 s) : first(f), second(s) {}

    /// \brief Template constructor.
    ///
    /// Template constructor. It copies everything which has
    /// \c first and \c second member.
    template <class Pair>
    extended_pair(const Pair& pair) : first(pair.first), second(pair.second) {}

    /// \brief The first value
    /// 
    /// The first value
    T1 first;
    /// \brief The second value
    /// 
    /// The second value
    T2 second;
  };

  /// \brief Equality operator
  /// 
  /// Equality operator
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator==(const extended_pair<T1, LA1, T2, LA2>& left, 
		  const extended_pair<T1, RA1, T2, RA2>& right) {
    return left.first == right.first && left.second == right.second;
  }

  /// \brief Inequality operator.
  /// 
  /// Inequality operator.
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator!=(const extended_pair<T1, LA1, T2, LA2>& left, 
		  const extended_pair<T1, RA1, T2, RA2>& right) {
    return  !(left == right);
  }

  /// \brief Less operator.
  /// 
  /// Less operator.
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator<(const extended_pair<T1, LA1, T2, LA2>& left, 
		 const extended_pair<T1, RA1, T2, RA2>& right) {
    return left.first < right.first || 
      (!(right.first<left.first) && left.second < right.second);
  }

  /// \brief Greater operator.
  /// 
  /// Greater operator.
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator>(const extended_pair<T1, LA1, T2, LA2>& left, 
		 const extended_pair<T1, RA1, T2, RA2>& right) {
    return right < left;
  }

  /// \brief Less or equal operator.
  /// 
  /// Less or equal operator.
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator<=(const extended_pair<T1, LA1, T2, LA2>& left, 
		  const extended_pair<T1, RA1, T2, RA2>& right) {
    return !(right > left);
  }

  /// \brief Greater or equal operator.
  /// 
  /// Greater or equal operator.
  template <typename T1, typename T2, 
	    typename LA1, typename LA2, typename RA1, typename RA2>
  bool operator>=(const extended_pair<T1, LA1, T2, LA2>& left, 
		  const extended_pair<T1, RA1, T2, RA2>& right) {
    return !(right < left);
  }

}
#endif