/* -*- mode: C++; indent-tabs-mode: nil; -*-

  *

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

  *

  * Copyright (C) 2003-2009

  * 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_CONCEPTS_HEAP_H

 #define LEMON_CONCEPTS_HEAP_H

 ///\ingroup concept

 ///\file

 ///\brief The concept of heaps.

 #include <lemon/core.h>

 #include <lemon/concept_check.h>

 namespace lemon {

   namespace concepts {

     /// \addtogroup concept

     /// @{

     /// \brief The heap concept.

     ///

     /// This concept class describes the main interface of heaps.

     /// The various \ref heaps "heap structures" are efficient

     /// implementations of the abstract data type \e priority \e queue.

     /// They store items with specified values called \e priorities

     /// in such a way that finding and removing the item with minimum

     /// priority are efficient. The basic operations are adding and

     /// erasing items, changing the priority of an item, etc.

     ///

     /// Heaps are crucial in several algorithms, such as Dijkstra and Prim.

     /// Any class that conforms to this concept can be used easily in such

     /// algorithms.

     ///

     /// \tparam PR Type of the priorities of the items.

     /// \tparam IM A read-writable item map with \c int values, used

     /// internally to handle the cross references.

     /// \tparam CMP A functor class for comparing the priorities.

     /// The default is \c std::less<PR>.

 #ifdef DOXYGEN

     template <typename PR, typename IM, typename CMP>

 #else

     template <typename PR, typename IM, typename CMP = std::less<PR> >

 #endif

     class Heap {

     public:

       /// Type of the item-int map.

       typedef IM ItemIntMap;

       /// Type of the priorities.

       typedef PR Prio;

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

       typedef typename ItemIntMap::Key Item;

       /// \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 latter two are indifferent from the

       /// heap's point of view, but may be useful to the user.

       ///

       /// The item-int map must be initialized in such way that it assigns

       /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.

       enum State {

         IN_HEAP = 0,    ///< = 0. The "in heap" state constant.

         PRE_HEAP = -1,  ///< = -1. The "pre-heap" state constant.

         POST_HEAP = -2  ///< = -2. The "post-heap" state constant.

       };

       /// \brief Constructor.

       ///

       /// 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 each item.

       explicit Heap(ItemIntMap &map) {}

       /// \brief Constructor.

       ///

       /// 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 each item.

       /// \param comp The function object used for comparing the priorities.

       explicit Heap(ItemIntMap &map, const CMP &comp) {}

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

       ///

       /// This function returns the number of items stored in the heap.

       int size() const { return 0; }

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

       ///

       /// This function returns \c true if the heap is empty.

       bool empty() const { return false; }

       /// \brief Make the heap empty.

       ///

       /// This functon makes the heap empty.

       /// It does not change the cross reference map. If you want to reuse

       /// a heap that is not surely empty, you should first clear it and

       /// then you should set the cross reference map to \c PRE_HEAP

       /// for each item.

       void clear() {}

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

       ///

       /// This function inserts the given item into the heap with the

       /// given priority.

       /// \param i The item to insert.

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

       /// \pre \e i must not be stored in the heap.

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

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

       ///

       /// This function returns the item having minimum priority.

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

       Item top() const {}

       /// \brief The minimum priority.

       ///

       /// This function returns the minimum priority.

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

       Prio prio() const {}

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

       ///

       /// This function removes the item having minimum priority.

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

       void pop() {}

       /// \brief Remove the given item from the heap.

       ///

       /// This function removes the given item from the heap if it is

       /// already stored.

       /// \param i The item to delete.

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

       void erase(const Item &i) {}

       /// \brief The priority of the given item.

       ///

       /// This function returns the priority of the given item.

       /// \param i The item.

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

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

       /// \brief Set the priority of an item or insert 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 into the heap with the given priority.

       ///

       /// \param i The item.

       /// \param p The priority.

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

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

       ///

       /// This function decreases the priority of an item to the given value.

       /// \param i The item.

       /// \param p The priority.

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

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

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

       ///

       /// This function increases the priority of an item to the given value.

       /// \param i The item.

       /// \param p The priority.

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

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

       /// \brief Return the state of an item.

       ///

       /// 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 Set the state of an item in the heap.

       ///

       /// This function 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 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