alpar@209: /* -*- mode: C++; indent-tabs-mode: nil; -*-
alpar@100:  *
alpar@209:  * This file is a part of LEMON, a generic C++ optimization library.
alpar@100:  *
alpar@877:  * Copyright (C) 2003-2010
alpar@100:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@100:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@100:  *
alpar@100:  * Permission to use, modify and distribute this software is granted
alpar@100:  * provided that this copyright notice appears in all copies. For
alpar@100:  * precise terms see the accompanying LICENSE file.
alpar@100:  *
alpar@100:  * This software is provided "AS IS" with no warranty of any kind,
alpar@100:  * express or implied, and with no claim as to its suitability for any
alpar@100:  * purpose.
alpar@100:  *
alpar@100:  */
alpar@100: 
kpeter@709: #ifndef LEMON_CONCEPTS_HEAP_H
kpeter@709: #define LEMON_CONCEPTS_HEAP_H
kpeter@709: 
alpar@100: ///\ingroup concept
alpar@100: ///\file
kpeter@113: ///\brief The concept of heaps.
alpar@100: 
deba@220: #include <lemon/core.h>
deba@519: #include <lemon/concept_check.h>
alpar@100: 
alpar@100: namespace lemon {
kpeter@113: 
alpar@100:   namespace concepts {
kpeter@113: 
alpar@100:     /// \addtogroup concept
alpar@100:     /// @{
alpar@100: 
kpeter@113:     /// \brief The heap concept.
alpar@100:     ///
kpeter@709:     /// This concept class describes the main interface of heaps.
kpeter@710:     /// The various \ref heaps "heap structures" are efficient
kpeter@709:     /// implementations of the abstract data type \e priority \e queue.
kpeter@709:     /// They store items with specified values called \e priorities
kpeter@709:     /// in such a way that finding and removing the item with minimum
kpeter@709:     /// priority are efficient. The basic operations are adding and
kpeter@709:     /// erasing items, changing the priority of an item, etc.
kpeter@559:     ///
kpeter@709:     /// Heaps are crucial in several algorithms, such as Dijkstra and Prim.
kpeter@709:     /// Any class that conforms to this concept can be used easily in such
kpeter@709:     /// algorithms.
kpeter@709:     ///
kpeter@709:     /// \tparam PR Type of the priorities of the items.
kpeter@709:     /// \tparam IM A read-writable item map with \c int values, used
kpeter@559:     /// internally to handle the cross references.
kpeter@709:     /// \tparam CMP A functor class for comparing the priorities.
kpeter@559:     /// The default is \c std::less<PR>.
kpeter@559: #ifdef DOXYGEN
kpeter@709:     template <typename PR, typename IM, typename CMP>
kpeter@559: #else
kpeter@709:     template <typename PR, typename IM, typename CMP = std::less<PR> >
kpeter@559: #endif
alpar@100:     class Heap {
alpar@100:     public:
alpar@100: 
kpeter@559:       /// Type of the item-int map.
kpeter@559:       typedef IM ItemIntMap;
kpeter@559:       /// Type of the priorities.
kpeter@559:       typedef PR Prio;
kpeter@113:       /// Type of the items stored in the heap.
kpeter@113:       typedef typename ItemIntMap::Key Item;
alpar@100: 
kpeter@113:       /// \brief Type to represent the states of the items.
alpar@100:       ///
kpeter@113:       /// Each item has a state associated to it. It can be "in heap",
kpeter@709:       /// "pre-heap" or "post-heap". The latter two are indifferent from the
kpeter@709:       /// heap's point of view, but may be useful to the user.
alpar@100:       ///
kpeter@559:       /// The item-int map must be initialized in such way that it assigns
kpeter@559:       /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
alpar@100:       enum State {
kpeter@584:         IN_HEAP = 0,    ///< = 0. The "in heap" state constant.
kpeter@709:         PRE_HEAP = -1,  ///< = -1. The "pre-heap" state constant.
kpeter@709:         POST_HEAP = -2  ///< = -2. The "post-heap" state constant.
alpar@100:       };
alpar@209: 
kpeter@709:       /// \brief Constructor.
alpar@100:       ///
kpeter@709:       /// Constructor.
kpeter@113:       /// \param map A map that assigns \c int values to keys of type
kpeter@113:       /// \c Item. It is used internally by the heap implementations to
kpeter@113:       /// handle the cross references. The assigned value must be
kpeter@709:       /// \c PRE_HEAP (<tt>-1</tt>) for each item.
kpeter@817: #ifdef DOXYGEN
kpeter@113:       explicit Heap(ItemIntMap &map) {}
kpeter@817: #else
kpeter@817:       explicit Heap(ItemIntMap&) {}
alpar@877: #endif
kpeter@584: 
kpeter@709:       /// \brief Constructor.
kpeter@709:       ///
kpeter@709:       /// Constructor.
kpeter@709:       /// \param map A map that assigns \c int values to keys of type
kpeter@709:       /// \c Item. It is used internally by the heap implementations to
kpeter@709:       /// handle the cross references. The assigned value must be
kpeter@709:       /// \c PRE_HEAP (<tt>-1</tt>) for each item.
kpeter@709:       /// \param comp The function object used for comparing the priorities.
kpeter@817: #ifdef DOXYGEN
kpeter@709:       explicit Heap(ItemIntMap &map, const CMP &comp) {}
kpeter@817: #else
kpeter@817:       explicit Heap(ItemIntMap&, const CMP&) {}
alpar@877: #endif
alpar@100: 
alpar@100:       /// \brief The number of items stored in the heap.
alpar@100:       ///
kpeter@709:       /// This function returns the number of items stored in the heap.
alpar@100:       int size() const { return 0; }
alpar@100: 
kpeter@709:       /// \brief Check if the heap is empty.
alpar@100:       ///
kpeter@709:       /// This function returns \c true if the heap is empty.
alpar@100:       bool empty() const { return false; }
alpar@100: 
kpeter@709:       /// \brief Make the heap empty.
alpar@100:       ///
kpeter@709:       /// This functon makes the heap empty.
kpeter@709:       /// It does not change the cross reference map. If you want to reuse
kpeter@709:       /// a heap that is not surely empty, you should first clear it and
kpeter@709:       /// then you should set the cross reference map to \c PRE_HEAP
kpeter@709:       /// for each item.
kpeter@709:       void clear() {}
alpar@100: 
kpeter@709:       /// \brief Insert an item into the heap with the given priority.
alpar@209:       ///
kpeter@709:       /// This function inserts the given item into the heap with the
kpeter@709:       /// given priority.
alpar@100:       /// \param i The item to insert.
alpar@100:       /// \param p The priority of the item.
kpeter@709:       /// \pre \e i must not be stored in the heap.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void push(const Item &i, const Prio &p) {}
kpeter@817: #else
kpeter@817:       void push(const Item&, const Prio&) {}
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief Return the item having minimum priority.
alpar@100:       ///
kpeter@709:       /// This function returns the item having minimum priority.
kpeter@113:       /// \pre The heap must be non-empty.
kpeter@817:       Item top() const { return Item(); }
alpar@100: 
kpeter@113:       /// \brief The minimum priority.
alpar@100:       ///
kpeter@709:       /// This function returns the minimum priority.
kpeter@113:       /// \pre The heap must be non-empty.
kpeter@817:       Prio prio() const { return Prio(); }
alpar@100: 
kpeter@709:       /// \brief Remove the item having minimum priority.
alpar@100:       ///
kpeter@709:       /// This function removes the item having minimum priority.
kpeter@113:       /// \pre The heap must be non-empty.
alpar@100:       void pop() {}
alpar@100: 
kpeter@709:       /// \brief Remove the given item from the heap.
alpar@100:       ///
kpeter@709:       /// This function removes the given item from the heap if it is
kpeter@709:       /// already stored.
alpar@209:       /// \param i The item to delete.
kpeter@709:       /// \pre \e i must be in the heap.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void erase(const Item &i) {}
kpeter@817: #else
kpeter@817:       void erase(const Item&) {}
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief The priority of the given item.
alpar@100:       ///
kpeter@709:       /// This function returns the priority of the given item.
kpeter@559:       /// \param i The item.
kpeter@709:       /// \pre \e i must be in the heap.
kpeter@817: #ifdef DOXYGEN
alpar@100:       Prio operator[](const Item &i) const {}
kpeter@817: #else
kpeter@817:       Prio operator[](const Item&) const { return Prio(); }
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief Set the priority of an item or insert it, if it is
kpeter@113:       /// not stored in the heap.
alpar@100:       ///
kpeter@113:       /// This method sets the priority of the given item if it is
kpeter@709:       /// already stored in the heap. Otherwise it inserts the given
kpeter@709:       /// item into the heap with the given priority.
kpeter@113:       ///
alpar@100:       /// \param i The item.
alpar@100:       /// \param p The priority.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void set(const Item &i, const Prio &p) {}
kpeter@817: #else
kpeter@817:       void set(const Item&, const Prio&) {}
alpar@877: #endif
alpar@209: 
kpeter@709:       /// \brief Decrease the priority of an item to the given value.
alpar@100:       ///
kpeter@709:       /// This function decreases the priority of an item to the given value.
alpar@100:       /// \param i The item.
alpar@100:       /// \param p The priority.
kpeter@709:       /// \pre \e i must be stored in the heap with priority at least \e p.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void decrease(const Item &i, const Prio &p) {}
kpeter@817: #else
kpeter@817:       void decrease(const Item&, const Prio&) {}
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief Increase the priority of an item to the given value.
alpar@100:       ///
kpeter@709:       /// This function increases the priority of an item to the given value.
alpar@100:       /// \param i The item.
alpar@100:       /// \param p The priority.
kpeter@709:       /// \pre \e i must be stored in the heap with priority at most \e p.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void increase(const Item &i, const Prio &p) {}
kpeter@817: #else
kpeter@817:       void increase(const Item&, const Prio&) {}
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief Return the state of an item.
alpar@100:       ///
kpeter@113:       /// This method returns \c PRE_HEAP if the given item has never
kpeter@113:       /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
kpeter@113:       /// and \c POST_HEAP otherwise.
kpeter@113:       /// In the latter case it is possible that the item will get back
kpeter@113:       /// to the heap again.
alpar@100:       /// \param i The item.
kpeter@817: #ifdef DOXYGEN
alpar@100:       State state(const Item &i) const {}
kpeter@817: #else
kpeter@817:       State state(const Item&) const { return PRE_HEAP; }
alpar@877: #endif
alpar@100: 
kpeter@709:       /// \brief Set the state of an item in the heap.
alpar@100:       ///
kpeter@709:       /// This function sets the state of the given item in the heap.
kpeter@709:       /// It can be used to manually clear the heap when it is important
kpeter@709:       /// to achive better time complexity.
alpar@100:       /// \param i The item.
kpeter@113:       /// \param st The state. It should not be \c IN_HEAP.
kpeter@817: #ifdef DOXYGEN
alpar@100:       void state(const Item& i, State st) {}
kpeter@817: #else
kpeter@817:       void state(const Item&, State) {}
alpar@877: #endif
alpar@100: 
alpar@100: 
alpar@100:       template <typename _Heap>
alpar@100:       struct Constraints {
alpar@100:       public:
alpar@209:         void constraints() {
alpar@209:           typedef typename _Heap::Item OwnItem;
alpar@209:           typedef typename _Heap::Prio OwnPrio;
alpar@209:           typedef typename _Heap::State OwnState;
kpeter@113: 
alpar@209:           Item item;
alpar@209:           Prio prio;
alpar@209:           item=Item();
alpar@209:           prio=Prio();
alpar@209:           ignore_unused_variable_warning(item);
alpar@209:           ignore_unused_variable_warning(prio);
alpar@100: 
alpar@209:           OwnItem own_item;
alpar@209:           OwnPrio own_prio;
alpar@209:           OwnState own_state;
alpar@209:           own_item=Item();
alpar@209:           own_prio=Prio();
alpar@209:           ignore_unused_variable_warning(own_item);
alpar@209:           ignore_unused_variable_warning(own_prio);
alpar@209:           ignore_unused_variable_warning(own_state);
alpar@100: 
alpar@209:           _Heap heap1(map);
alpar@209:           _Heap heap2 = heap1;
alpar@209:           ignore_unused_variable_warning(heap1);
alpar@209:           ignore_unused_variable_warning(heap2);
alpar@100: 
alpar@209:           int s = heap.size();
alpar@209:           ignore_unused_variable_warning(s);
alpar@209:           bool e = heap.empty();
alpar@209:           ignore_unused_variable_warning(e);
alpar@100: 
alpar@209:           prio = heap.prio();
alpar@209:           item = heap.top();
alpar@209:           prio = heap[item];
alpar@209:           own_prio = heap.prio();
alpar@209:           own_item = heap.top();
alpar@209:           own_prio = heap[own_item];
alpar@100: 
alpar@209:           heap.push(item, prio);
alpar@209:           heap.push(own_item, own_prio);
alpar@209:           heap.pop();
alpar@100: 
alpar@209:           heap.set(item, prio);
alpar@209:           heap.decrease(item, prio);
alpar@209:           heap.increase(item, prio);
alpar@209:           heap.set(own_item, own_prio);
alpar@209:           heap.decrease(own_item, own_prio);
alpar@209:           heap.increase(own_item, own_prio);
alpar@100: 
alpar@209:           heap.erase(item);
alpar@209:           heap.erase(own_item);
alpar@209:           heap.clear();
alpar@100: 
alpar@209:           own_state = heap.state(own_item);
alpar@209:           heap.state(own_item, own_state);
alpar@100: 
alpar@209:           own_state = _Heap::PRE_HEAP;
alpar@209:           own_state = _Heap::IN_HEAP;
alpar@209:           own_state = _Heap::POST_HEAP;
alpar@209:         }
alpar@209: 
alpar@209:         _Heap& heap;
alpar@209:         ItemIntMap& map;
alpar@953:         Constraints() {}
alpar@100:       };
alpar@100:     };
alpar@100: 
alpar@100:     /// @}
alpar@100:   } // namespace lemon
alpar@100: }
deba@529: #endif