lemon/concepts/heap.h
author Akos Ladanyi <ladanyi@tmit.bme.hu>
Sun, 13 Apr 2008 13:22:52 +0200
changeset 141 96f81c791f0c
parent 100 4f754b4cf82b
child 203 215bfc30b14f
permissions -rw-r--r--
CMake based build system
     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2008
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 ///\ingroup concept
    20 ///\file
    21 ///\brief The concept of heaps.
    22 
    23 #ifndef LEMON_CONCEPT_HEAP_H
    24 #define LEMON_CONCEPT_HEAP_H
    25 
    26 #include <lemon/bits/invalid.h>
    27 
    28 namespace lemon {
    29 
    30   namespace concepts {
    31 
    32     /// \addtogroup concept
    33     /// @{
    34 
    35     /// \brief The heap concept.
    36     ///
    37     /// Concept class describing the main interface of heaps.
    38     template <typename Priority, typename ItemIntMap>
    39     class Heap {
    40     public:
    41 
    42       /// Type of the items stored in the heap.
    43       typedef typename ItemIntMap::Key Item;
    44 
    45       /// Type of the priorities.
    46       typedef Priority Prio;
    47 
    48       /// \brief Type to represent the states of the items.
    49       ///
    50       /// Each item has a state associated to it. It can be "in heap",
    51       /// "pre heap" or "post heap". The later two are indifferent
    52       /// from the point of view of the heap, but may be useful for
    53       /// the user.
    54       ///
    55       /// The \c ItemIntMap must be initialized in such a way, that it 
    56       /// assigns \c PRE_HEAP (<tt>-1</tt>) to every item.
    57       enum State {
    58 	IN_HEAP = 0,
    59 	PRE_HEAP = -1,
    60 	POST_HEAP = -2
    61       };
    62       
    63       /// \brief The constructor.
    64       ///
    65       /// The constructor.
    66       /// \param map A map that assigns \c int values to keys of type
    67       /// \c Item. It is used internally by the heap implementations to
    68       /// handle the cross references. The assigned value must be
    69       /// \c PRE_HEAP (<tt>-1</tt>) for every item.
    70       explicit Heap(ItemIntMap &map) {}
    71 
    72       /// \brief The number of items stored in the heap.
    73       ///
    74       /// Returns the number of items stored in the heap.
    75       int size() const { return 0; }
    76 
    77       /// \brief Checks if the heap is empty.
    78       ///
    79       /// Returns \c true if the heap is empty.
    80       bool empty() const { return false; }
    81 
    82       /// \brief Makes the heap empty.
    83       ///
    84       /// Makes the heap empty.
    85       void clear();
    86 
    87       /// \brief Inserts an item into the heap with the given priority.
    88       ///    
    89       /// Inserts the given item into the heap with the given priority. 
    90       /// \param i The item to insert.
    91       /// \param p The priority of the item.
    92       void push(const Item &i, const Prio &p) {}
    93 
    94       /// \brief Returns the item having minimum priority.
    95       ///
    96       /// Returns the item having minimum priority.
    97       /// \pre The heap must be non-empty.
    98       Item top() const {}
    99 
   100       /// \brief The minimum priority.
   101       ///
   102       /// Returns the minimum priority.
   103       /// \pre The heap must be non-empty.
   104       Prio prio() const {}
   105 
   106       /// \brief Removes the item having minimum priority.
   107       ///
   108       /// Removes the item having minimum priority.
   109       /// \pre The heap must be non-empty.
   110       void pop() {}
   111 
   112       /// \brief Removes an item from the heap.
   113       ///
   114       /// Removes the given item from the heap if it is already stored.
   115       /// \param i The item to delete. 
   116       void erase(const Item &i) {}
   117 
   118       /// \brief The priority of an item.
   119       ///
   120       /// Returns the priority of the given item.  
   121       /// \pre \c i must be in the heap.
   122       /// \param i The item.
   123       Prio operator[](const Item &i) const {}
   124 
   125       /// \brief Sets the priority of an item or inserts it, if it is
   126       /// not stored in the heap.
   127       ///
   128       /// This method sets the priority of the given item if it is
   129       /// already stored in the heap.
   130       /// Otherwise it inserts the given item with the given priority.
   131       ///
   132       /// It may throw an \ref UnderflowPriorityException.
   133       /// \param i The item.
   134       /// \param p The priority.
   135       void set(const Item &i, const Prio &p) {}
   136       
   137       /// \brief Decreases the priority of an item to the given value.
   138       ///
   139       /// Decreases the priority of an item to the given value.
   140       /// \pre \c i must be stored in the heap with priority at least \c p.
   141       /// \param i The item.
   142       /// \param p The priority.
   143       void decrease(const Item &i, const Prio &p) {}
   144 
   145       /// \brief Increases the priority of an item to the given value.
   146       ///
   147       /// Increases the priority of an item to the given value.
   148       /// \pre \c i must be stored in the heap with priority at most \c p.
   149       /// \param i The item.
   150       /// \param p The priority.
   151       void increase(const Item &i, const Prio &p) {}
   152 
   153       /// \brief Returns if an item is in, has already been in, or has
   154       /// never been in the heap.
   155       ///
   156       /// This method returns \c PRE_HEAP if the given item has never
   157       /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
   158       /// and \c POST_HEAP otherwise.
   159       /// In the latter case it is possible that the item will get back
   160       /// to the heap again.
   161       /// \param i The item.
   162       State state(const Item &i) const {}
   163 
   164       /// \brief Sets the state of an item in the heap.
   165       ///
   166       /// Sets the state of the given item in the heap. It can be used
   167       /// to manually clear the heap when it is important to achive the
   168       /// better time complexity.
   169       /// \param i The item.
   170       /// \param st The state. It should not be \c IN_HEAP.
   171       void state(const Item& i, State st) {}
   172 
   173 
   174       template <typename _Heap>
   175       struct Constraints {
   176       public:
   177 	void constraints() {
   178 	  typedef typename _Heap::Item OwnItem;
   179 	  typedef typename _Heap::Prio OwnPrio;
   180 	  typedef typename _Heap::State OwnState;
   181 
   182 	  Item item;
   183 	  Prio prio;
   184 	  State state;
   185 	  item=Item();
   186 	  prio=Prio();
   187 	  ignore_unused_variable_warning(item);
   188 	  ignore_unused_variable_warning(prio);
   189 	  ignore_unused_variable_warning(state);
   190 
   191 	  OwnItem own_item;
   192 	  OwnPrio own_prio;
   193 	  OwnState own_state;
   194 	  own_item=Item();
   195 	  own_prio=Prio();
   196 	  ignore_unused_variable_warning(own_item);
   197 	  ignore_unused_variable_warning(own_prio);
   198 	  ignore_unused_variable_warning(own_state);
   199 
   200 	  _Heap heap1(map);
   201 	  _Heap heap2 = heap1;
   202 	  ignore_unused_variable_warning(heap1);
   203 	  ignore_unused_variable_warning(heap2);
   204 	  
   205 	  int s = heap.size();
   206 	  bool e = heap.empty();
   207 
   208 	  prio = heap.prio();
   209 	  item = heap.top();
   210 	  prio = heap[item];
   211 	  own_prio = heap.prio();
   212 	  own_item = heap.top();
   213 	  own_prio = heap[own_item];
   214 
   215 	  heap.push(item, prio);
   216 	  heap.push(own_item, own_prio);
   217 	  heap.pop();
   218 
   219 	  heap.set(item, prio);
   220 	  heap.decrease(item, prio);
   221 	  heap.increase(item, prio);
   222 	  heap.set(own_item, own_prio);
   223 	  heap.decrease(own_item, own_prio);
   224 	  heap.increase(own_item, own_prio);
   225 
   226 	  heap.erase(item);
   227 	  heap.erase(own_item);
   228 	  heap.clear();
   229 
   230 	  state = heap.state(item);
   231 	  heap.state(item, state);
   232 	  state = heap.state(own_item);
   233 	  heap.state(own_item, own_state);
   234 
   235 	  state = _Heap::PRE_HEAP;
   236 	  state = _Heap::IN_HEAP;
   237 	  state = _Heap::POST_HEAP;
   238 	  own_state = _Heap::PRE_HEAP;
   239 	  own_state = _Heap::IN_HEAP;
   240 	  own_state = _Heap::POST_HEAP;
   241 	}
   242 
   243 	_Heap& heap;
   244 	ItemIntMap& map;
   245       };
   246     };
   247 
   248     /// @}
   249   } // namespace lemon
   250 }
   251 #endif // LEMON_CONCEPT_PATH_H