/* -*- 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;

 	  item=Item();

 	  prio=Prio();

 	  ignore_unused_variable_warning(item);

 	  ignore_unused_variable_warning(prio);

 	  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();

 	  ignore_unused_variable_warning(s);

 	  bool e = heap.empty();

 	  ignore_unused_variable_warning(e);

 	  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();

 	  own_state = heap.state(own_item);

 	  heap.state(own_item, own_state);

 	  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