COIN-OR::LEMON - Graph Library

source: lemon-1.2/lemon/concepts/heap.h @ 817:b87f0504cdbe

Last change on this file since 817:b87f0504cdbe was 817:b87f0504cdbe, checked in by Peter Kovacs <kpeter@…>, 10 years ago

Fixes in the heap concept to avoid warnings (#180)

File size: 10.4 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2009
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#ifndef LEMON_CONCEPTS_HEAP_H
20#define LEMON_CONCEPTS_HEAP_H
21
22///\ingroup concept
23///\file
24///\brief The concept of heaps.
25
26#include <lemon/core.h>
27#include <lemon/concept_check.h>
28
29namespace lemon {
30
31  namespace concepts {
32
33    /// \addtogroup concept
34    /// @{
35
36    /// \brief The heap concept.
37    ///
38    /// This concept class describes the main interface of heaps.
39    /// The various \ref heaps "heap structures" are efficient
40    /// implementations of the abstract data type \e priority \e queue.
41    /// They store items with specified values called \e priorities
42    /// in such a way that finding and removing the item with minimum
43    /// priority are efficient. The basic operations are adding and
44    /// erasing items, changing the priority of an item, etc.
45    ///
46    /// Heaps are crucial in several algorithms, such as Dijkstra and Prim.
47    /// Any class that conforms to this concept can be used easily in such
48    /// algorithms.
49    ///
50    /// \tparam PR Type of the priorities of the items.
51    /// \tparam IM A read-writable item map with \c int values, used
52    /// internally to handle the cross references.
53    /// \tparam CMP A functor class for comparing the priorities.
54    /// The default is \c std::less<PR>.
55#ifdef DOXYGEN
56    template <typename PR, typename IM, typename CMP>
57#else
58    template <typename PR, typename IM, typename CMP = std::less<PR> >
59#endif
60    class Heap {
61    public:
62
63      /// Type of the item-int map.
64      typedef IM ItemIntMap;
65      /// Type of the priorities.
66      typedef PR Prio;
67      /// Type of the items stored in the heap.
68      typedef typename ItemIntMap::Key Item;
69
70      /// \brief Type to represent the states of the items.
71      ///
72      /// Each item has a state associated to it. It can be "in heap",
73      /// "pre-heap" or "post-heap". The latter two are indifferent from the
74      /// heap's point of view, but may be useful to the user.
75      ///
76      /// The item-int map must be initialized in such way that it assigns
77      /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
78      enum State {
79        IN_HEAP = 0,    ///< = 0. The "in heap" state constant.
80        PRE_HEAP = -1,  ///< = -1. The "pre-heap" state constant.
81        POST_HEAP = -2  ///< = -2. The "post-heap" state constant.
82      };
83
84      /// \brief Constructor.
85      ///
86      /// Constructor.
87      /// \param map A map that assigns \c int values to keys of type
88      /// \c Item. It is used internally by the heap implementations to
89      /// handle the cross references. The assigned value must be
90      /// \c PRE_HEAP (<tt>-1</tt>) for each item.
91#ifdef DOXYGEN
92      explicit Heap(ItemIntMap &map) {}
93#else
94      explicit Heap(ItemIntMap&) {}
95#endif     
96
97      /// \brief Constructor.
98      ///
99      /// Constructor.
100      /// \param map A map that assigns \c int values to keys of type
101      /// \c Item. It is used internally by the heap implementations to
102      /// handle the cross references. The assigned value must be
103      /// \c PRE_HEAP (<tt>-1</tt>) for each item.
104      /// \param comp The function object used for comparing the priorities.
105#ifdef DOXYGEN
106      explicit Heap(ItemIntMap &map, const CMP &comp) {}
107#else
108      explicit Heap(ItemIntMap&, const CMP&) {}
109#endif     
110
111      /// \brief The number of items stored in the heap.
112      ///
113      /// This function returns the number of items stored in the heap.
114      int size() const { return 0; }
115
116      /// \brief Check if the heap is empty.
117      ///
118      /// This function returns \c true if the heap is empty.
119      bool empty() const { return false; }
120
121      /// \brief Make the heap empty.
122      ///
123      /// This functon makes the heap empty.
124      /// It does not change the cross reference map. If you want to reuse
125      /// a heap that is not surely empty, you should first clear it and
126      /// then you should set the cross reference map to \c PRE_HEAP
127      /// for each item.
128      void clear() {}
129
130      /// \brief Insert an item into the heap with the given priority.
131      ///
132      /// This function inserts the given item into the heap with the
133      /// given priority.
134      /// \param i The item to insert.
135      /// \param p The priority of the item.
136      /// \pre \e i must not be stored in the heap.
137#ifdef DOXYGEN
138      void push(const Item &i, const Prio &p) {}
139#else
140      void push(const Item&, const Prio&) {}
141#endif     
142
143      /// \brief Return the item having minimum priority.
144      ///
145      /// This function returns the item having minimum priority.
146      /// \pre The heap must be non-empty.
147      Item top() const { return Item(); }
148
149      /// \brief The minimum priority.
150      ///
151      /// This function returns the minimum priority.
152      /// \pre The heap must be non-empty.
153      Prio prio() const { return Prio(); }
154
155      /// \brief Remove the item having minimum priority.
156      ///
157      /// This function removes the item having minimum priority.
158      /// \pre The heap must be non-empty.
159      void pop() {}
160
161      /// \brief Remove the given item from the heap.
162      ///
163      /// This function removes the given item from the heap if it is
164      /// already stored.
165      /// \param i The item to delete.
166      /// \pre \e i must be in the heap.
167#ifdef DOXYGEN
168      void erase(const Item &i) {}
169#else
170      void erase(const Item&) {}
171#endif     
172
173      /// \brief The priority of the given item.
174      ///
175      /// This function returns the priority of the given item.
176      /// \param i The item.
177      /// \pre \e i must be in the heap.
178#ifdef DOXYGEN
179      Prio operator[](const Item &i) const {}
180#else
181      Prio operator[](const Item&) const { return Prio(); }
182#endif     
183
184      /// \brief Set the priority of an item or insert it, if it is
185      /// not stored in the heap.
186      ///
187      /// This method sets the priority of the given item if it is
188      /// already stored in the heap. Otherwise it inserts the given
189      /// item into the heap with the given priority.
190      ///
191      /// \param i The item.
192      /// \param p The priority.
193#ifdef DOXYGEN
194      void set(const Item &i, const Prio &p) {}
195#else
196      void set(const Item&, const Prio&) {}
197#endif     
198
199      /// \brief Decrease the priority of an item to the given value.
200      ///
201      /// This function decreases the priority of an item to the given value.
202      /// \param i The item.
203      /// \param p The priority.
204      /// \pre \e i must be stored in the heap with priority at least \e p.
205#ifdef DOXYGEN
206      void decrease(const Item &i, const Prio &p) {}
207#else
208      void decrease(const Item&, const Prio&) {}
209#endif     
210
211      /// \brief Increase the priority of an item to the given value.
212      ///
213      /// This function increases the priority of an item to the given value.
214      /// \param i The item.
215      /// \param p The priority.
216      /// \pre \e i must be stored in the heap with priority at most \e p.
217#ifdef DOXYGEN
218      void increase(const Item &i, const Prio &p) {}
219#else
220      void increase(const Item&, const Prio&) {}
221#endif     
222
223      /// \brief Return the state of an item.
224      ///
225      /// This method returns \c PRE_HEAP if the given item has never
226      /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
227      /// and \c POST_HEAP otherwise.
228      /// In the latter case it is possible that the item will get back
229      /// to the heap again.
230      /// \param i The item.
231#ifdef DOXYGEN
232      State state(const Item &i) const {}
233#else
234      State state(const Item&) const { return PRE_HEAP; }
235#endif     
236
237      /// \brief Set the state of an item in the heap.
238      ///
239      /// This function sets the state of the given item in the heap.
240      /// It can be used to manually clear the heap when it is important
241      /// to achive better time complexity.
242      /// \param i The item.
243      /// \param st The state. It should not be \c IN_HEAP.
244#ifdef DOXYGEN
245      void state(const Item& i, State st) {}
246#else
247      void state(const Item&, State) {}
248#endif     
249
250
251      template <typename _Heap>
252      struct Constraints {
253      public:
254        void constraints() {
255          typedef typename _Heap::Item OwnItem;
256          typedef typename _Heap::Prio OwnPrio;
257          typedef typename _Heap::State OwnState;
258
259          Item item;
260          Prio prio;
261          item=Item();
262          prio=Prio();
263          ignore_unused_variable_warning(item);
264          ignore_unused_variable_warning(prio);
265
266          OwnItem own_item;
267          OwnPrio own_prio;
268          OwnState own_state;
269          own_item=Item();
270          own_prio=Prio();
271          ignore_unused_variable_warning(own_item);
272          ignore_unused_variable_warning(own_prio);
273          ignore_unused_variable_warning(own_state);
274
275          _Heap heap1(map);
276          _Heap heap2 = heap1;
277          ignore_unused_variable_warning(heap1);
278          ignore_unused_variable_warning(heap2);
279
280          int s = heap.size();
281          ignore_unused_variable_warning(s);
282          bool e = heap.empty();
283          ignore_unused_variable_warning(e);
284
285          prio = heap.prio();
286          item = heap.top();
287          prio = heap[item];
288          own_prio = heap.prio();
289          own_item = heap.top();
290          own_prio = heap[own_item];
291
292          heap.push(item, prio);
293          heap.push(own_item, own_prio);
294          heap.pop();
295
296          heap.set(item, prio);
297          heap.decrease(item, prio);
298          heap.increase(item, prio);
299          heap.set(own_item, own_prio);
300          heap.decrease(own_item, own_prio);
301          heap.increase(own_item, own_prio);
302
303          heap.erase(item);
304          heap.erase(own_item);
305          heap.clear();
306
307          own_state = heap.state(own_item);
308          heap.state(own_item, own_state);
309
310          own_state = _Heap::PRE_HEAP;
311          own_state = _Heap::IN_HEAP;
312          own_state = _Heap::POST_HEAP;
313        }
314
315        _Heap& heap;
316        ItemIntMap& map;
317      };
318    };
319
320    /// @}
321  } // namespace lemon
322}
323#endif
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