/* -*- C++ -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2003-2008

 * 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.

 *

 */

///\ingroup concept

///\file

///\brief The concept of heaps.

#ifndef LEMON_CONCEPT_HEAP_H

#define LEMON_CONCEPT_HEAP_H

#include <lemon/bits/invalid.h>

namespace lemon {

  namespace concepts {

    /// \addtogroup concept

    /// @{

    /// \brief The heap concept.

    ///

    /// Concept class describing the main interface of heaps.

    template <typename Priority, typename ItemIntMap>

    class Heap {

    public:

      /// Type of the items stored in the heap.

      typedef typename ItemIntMap::Key Item;

      /// Type of the priorities.

      typedef Priority Prio;

      /// \brief Type to represent the states of the items.

      ///

      /// Each item has a state associated to it. It can be "in heap",

      /// "pre heap" or "post heap". The later two are indifferent

      /// from the point of view of the heap, but may be useful for

      /// the user.

      ///

      /// The \c ItemIntMap must be initialized in such a way, that it 

      /// assigns \c PRE_HEAP (<tt>-1</tt>) to every item.

      enum State {

	IN_HEAP = 0,

	PRE_HEAP = -1,

	POST_HEAP = -2

      };

      /// \brief The constructor.

      ///

      /// The constructor.

      /// \param map A map that assigns \c int values to keys of type

      /// \c Item. It is used internally by the heap implementations to

      /// handle the cross references. The assigned value must be

      /// \c PRE_HEAP (<tt>-1</tt>) for every item.

      explicit Heap(ItemIntMap &map) {}

      /// \brief The number of items stored in the heap.

      ///

      /// Returns the number of items stored in the heap.

      int size() const { return 0; }

      /// \brief Checks if the heap is empty.

      ///

      /// Returns \c true if the heap is empty.

      bool empty() const { return false; }

      /// \brief Makes the heap empty.

      ///

      /// Makes the heap empty.

      void clear();

      /// \brief Inserts an item into the heap with the given priority.

      ///    

      /// Inserts the given item into the heap with the given priority. 

      /// \param i The item to insert.

      /// \param p The priority of the item.

      void push(const Item &i, const Prio &p) {}

      /// \brief Returns the item having minimum priority.

      ///

      /// Returns the item having minimum priority.

      /// \pre The heap must be non-empty.

      Item top() const {}

      /// \brief The minimum priority.

      ///

      /// Returns the minimum priority.

      /// \pre The heap must be non-empty.

      Prio prio() const {}

      /// \brief Removes the item having minimum priority.

      ///

      /// Removes the item having minimum priority.

      /// \pre The heap must be non-empty.

      void pop() {}

      /// \brief Removes an item from the heap.

      ///

      /// Removes the given item from the heap if it is already stored.

      /// \param i The item to delete. 

      void erase(const Item &i) {}

      /// \brief The priority of an item.

      ///

      /// Returns the priority of the given item.  

      /// \pre \c i must be in the heap.

      /// \param i The item.

      Prio operator[](const Item &i) const {}

      /// \brief Sets the priority of an item or inserts it, if it is

      /// not stored in the heap.

      ///

      /// This method sets the priority of the given item if it is

      /// already stored in the heap.

      /// Otherwise it inserts the given item with the given priority.

      ///

      /// It may throw an \ref UnderflowPriorityException.

      /// \param i The item.

      /// \param p The priority.

      void set(const Item &i, const Prio &p) {}

      /// \brief Decreases the priority of an item to the given value.

      ///

      /// Decreases the priority of an item to the given value.

      /// \pre \c i must be stored in the heap with priority at least \c p.

      /// \param i The item.

      /// \param p The priority.

      void decrease(const Item &i, const Prio &p) {}

      /// \brief Increases the priority of an item to the given value.

      ///

      /// Increases the priority of an item to the given value.

      /// \pre \c i must be stored in the heap with priority at most \c p.

      /// \param i The item.

      /// \param p The priority.

      void increase(const Item &i, const Prio &p) {}

      /// \brief Returns if an item is in, has already been in, or has

      /// never been in the heap.

      ///

      /// This method returns \c PRE_HEAP if the given item has never

      /// been in the heap, \c IN_HEAP if it is in the heap at the moment,

      /// and \c POST_HEAP otherwise.

      /// In the latter case it is possible that the item will get back

      /// to the heap again.

      /// \param i The item.

      State state(const Item &i) const {}

      /// \brief Sets the state of an item in the heap.

      ///

      /// Sets the state of the given item in the heap. It can be used

      /// to manually clear the heap when it is important to achive the

      /// better time complexity.

      /// \param i The item.

      /// \param st The state. It should not be \c IN_HEAP.

      void state(const Item& i, State st) {}

      template <typename _Heap>

      struct Constraints {

      public:

	void constraints() {

	  typedef typename _Heap::Item OwnItem;

	  typedef typename _Heap::Prio OwnPrio;

	  typedef typename _Heap::State OwnState;

	  Item item;

	  Prio prio;

	  State state;

	  item=Item();

	  prio=Prio();

	  ignore_unused_variable_warning(item);

	  ignore_unused_variable_warning(prio);

	  ignore_unused_variable_warning(state);

	  OwnItem own_item;

	  OwnPrio own_prio;

	  OwnState own_state;

	  own_item=Item();

	  own_prio=Prio();

	  ignore_unused_variable_warning(own_item);

	  ignore_unused_variable_warning(own_prio);

	  ignore_unused_variable_warning(own_state);

	  _Heap heap1(map);

	  _Heap heap2 = heap1;

	  ignore_unused_variable_warning(heap1);

	  ignore_unused_variable_warning(heap2);

	  int s = heap.size();

	  bool e = heap.empty();

	  prio = heap.prio();

	  item = heap.top();

	  prio = heap[item];

	  own_prio = heap.prio();

	  own_item = heap.top();

	  own_prio = heap[own_item];

	  heap.push(item, prio);

	  heap.push(own_item, own_prio);

	  heap.pop();

	  heap.set(item, prio);

	  heap.decrease(item, prio);

	  heap.increase(item, prio);

	  heap.set(own_item, own_prio);

	  heap.decrease(own_item, own_prio);

	  heap.increase(own_item, own_prio);

	  heap.erase(item);

	  heap.erase(own_item);

	  heap.clear();

	  state = heap.state(item);

	  heap.state(item, state);

	  state = heap.state(own_item);

	  heap.state(own_item, own_state);

	  state = _Heap::PRE_HEAP;

	  state = _Heap::IN_HEAP;

	  state = _Heap::POST_HEAP;

	  own_state = _Heap::PRE_HEAP;

	  own_state = _Heap::IN_HEAP;

	  own_state = _Heap::POST_HEAP;

	}

	_Heap& heap;

	ItemIntMap& map;

      };

    };

    /// @}

  } // namespace lemon

}

#endif // LEMON_CONCEPT_PATH_H