HeapT.hh 10.9 KB
Newer Older
1
2
3
/*===========================================================================*\
 *                                                                           *
 *                               OpenMesh                                    *
Jan Möbius's avatar
Jan Möbius committed
4
 *      Copyright (C) 2001-2012 by Computer Graphics Group, RWTH Aachen      *
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
 *                           www.openmesh.org                                *
 *                                                                           *
 *---------------------------------------------------------------------------* 
 *  This file is part of OpenMesh.                                           *
 *                                                                           *
 *  OpenMesh is free software: you can redistribute it and/or modify         * 
 *  it under the terms of the GNU Lesser General Public License as           *
 *  published by the Free Software Foundation, either version 3 of           *
 *  the License, or (at your option) any later version with the              *
 *  following exceptions:                                                    *
 *                                                                           *
 *  If other files instantiate templates or use macros                       *
 *  or inline functions from this file, or you compile this file and         *
 *  link it with other files to produce an executable, this file does        *
 *  not by itself cause the resulting executable to be covered by the        *
 *  GNU Lesser General Public License. This exception does not however       *
 *  invalidate any other reasons why the executable file might be            *
 *  covered by the GNU Lesser General Public License.                        *
 *                                                                           *
 *  OpenMesh is distributed in the hope that it will be useful,              *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            *
 *  GNU Lesser General Public License for more details.                      *
 *                                                                           *
 *  You should have received a copy of the GNU LesserGeneral Public          *
 *  License along with OpenMesh.  If not,                                    *
 *  see <http://www.gnu.org/licenses/>.                                      *
 *                                                                           *
\*===========================================================================*/ 

/*===========================================================================*\
 *                                                                           *             
 *   $Revision$                                                         *
 *   $Date$                   *
 *                                                                           *
\*===========================================================================*/
Jan Möbius's avatar
Jan Möbius committed
41

Jan Möbius's avatar
Jan Möbius committed
42
/** \file Tools/Utils/HeapT.hh
Jan Möbius's avatar
Jan Möbius committed
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
    A generic heap class
**/
/** Martin, 26.12.2004: 
    1) replaced resize(size()-1) with pop_back(), since the later is more efficient
    2) replaced interface_.set_heap_position(entry(0), -1); with reset_heap_position()
    3) added const modifier to various functions
    TODO: in the moment the heap does not conform to the HeapInterface specification, 
          i.e., copies are passed instead of references. This is especially important 
          for set_heap_position(), where the reference argument is non-const. The 
          specification should be changed to reflect that the heap actually (only?)
          works when the heap entry is nothing more but a handle.
    TODO: change the specification of HeapInterface to make less(), greater() and
          get_heap_position() const. Needs changing DecimaterT. Might break 
          someone's code.
*/
    

//=============================================================================
//
//  CLASS HeapT
//
//=============================================================================

#ifndef OPENMESH_UTILS_HEAPT_HH
#define OPENMESH_UTILS_HEAPT_HH


//== INCLUDES =================================================================

#include "Config.hh"
#include <vector>
#include <OpenMesh/Core/System/omstream.hh>

//== NAMESPACE ================================================================

namespace OpenMesh { // BEGIN_NS_OPENMESH
namespace Utils { // BEGIN_NS_UTILS

//== CLASS DEFINITION =========================================================


/** This class demonstrates the HeapInterface's interface.  If you
Jan Möbius's avatar
Jan Möbius committed
85
 *  want to build your customized heap you will have to specify a heap
Jan Möbius's avatar
Jan Möbius committed
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
 *  interface class and use this class as a template parameter for the
 *  class HeapT. This class defines the interface that this heap
 *  interface has to implement.
 *   
 *  \see HeapT
 */
template <class HeapEntry>
struct HeapInterfaceT
{
  /// Comparison of two HeapEntry's: strict less
  bool less(const HeapEntry& _e1, const HeapEntry& _e2);

  /// Comparison of two HeapEntry's: strict greater
  bool greater(const HeapEntry& _e1, const HeapEntry& _e2);

  /// Get the heap position of HeapEntry _e
  int  get_heap_position(const HeapEntry& _e);

  /// Set the heap position of HeapEntry _e
  void set_heap_position(HeapEntry& _e, int _i);
};



/** \class HeapT HeapT.hh <OSG/Utils/HeapT.hh>
 *
 *  An efficient, highly customizable heap.
 *
Jan Möbius's avatar
Jan Möbius committed
114
115
 *  The main difference (and performance boost) of this heap compared
 *  to e.g. the heap of the STL is that here the positions of the
Jan Möbius's avatar
Jan Möbius committed
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
 *  heap's elements are accessible from the elements themself.
 *  Therefore if one changes the priority of an element one does not
 *  have to remove and re-insert this element, but can just call the
 *  update(HeapEntry) method.
 *
 *  This heap class is parameterized by two template arguments: 
 *  \li the class \c HeapEntry, that will be stored in the heap 
 *  \li the HeapInterface telling the heap how to compare heap entries and
 *      how to store the heap positions in the heap entries.
 *
 *  As an example how to use the class see declaration of class 
 *  Decimater::DecimaterT.
 *
 *  \see HeapInterfaceT
 */
 
template <class HeapEntry, class HeapInterface=HeapEntry>
class HeapT : private std::vector<HeapEntry>
{
private: 
  typedef std::vector<HeapEntry>            Base;
  
public:

  /// Constructor
  HeapT() : HeapVector() {}
  
  /// Construct with a given \c HeapIterface. 
  HeapT(const HeapInterface& _interface)
  : HeapVector(),  interface_(_interface)
  {}
  
  /// Destructor.
  ~HeapT(){};


  /// clear the heap
  void clear() { HeapVector::clear(); }

  /// is heap empty?
  bool empty() const { return HeapVector::empty(); }

  /// returns the size of heap
159
  size_t size() const { return HeapVector::size(); }
Jan Möbius's avatar
Jan Möbius committed
160
161

  /// reserve space for _n entries
162
  void reserve(size_t _n) { HeapVector::reserve(_n); }
Jan Möbius's avatar
Jan Möbius committed
163
164
165
166
167
168
169
170
171
172
173
174

  /// reset heap position to -1 (not in heap)
  void reset_heap_position(HeapEntry _h)
  { interface_.set_heap_position(_h, -1); }
  
  /// is an entry in the heap?
  bool is_stored(HeapEntry _h)
  { return interface_.get_heap_position(_h) != -1; }
  
  /// insert the entry _h
  void insert(HeapEntry _h)  
  { 
175
    this->push_back(_h); 
Jan Möbius's avatar
Jan Möbius committed
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
    upheap(size()-1); 
  }

  /// get the first entry
  HeapEntry front() const
  { 
    assert(!empty()); 
    return entry(0); 
  }

  /// delete the first entry
  void pop_front()
  {    
    assert(!empty());
    reset_heap_position(entry(0));
    if (size() > 1)
    {
      entry(0, entry(size()-1));
      Base::pop_back();
      downheap(0);
    }
    else
    {
      Base::pop_back();
    }
  }

  /// remove an entry
  void remove(HeapEntry _h)
  {
    int pos = interface_.get_heap_position(_h);
    reset_heap_position(_h);

    assert(pos != -1);
    assert((unsigned int) pos < size());
    
    // last item ?
    if ((unsigned int) pos == size()-1)
    {
      Base::pop_back();    
    }
    else 
    {
      entry(pos, entry(size()-1)); // move last elem to pos
      Base::pop_back();
      downheap(pos);
      upheap(pos);
    }
  }

  /** update an entry: change the key and update the position to
      reestablish the heap property.
  */
  void update(HeapEntry _h)
  {
    int pos = interface_.get_heap_position(_h);
    assert(pos != -1);
    assert((unsigned int)pos < size());
    downheap(pos);
    upheap(pos);
  }
  
  /// check heap condition
  bool check()
  {
    bool ok(true);
    unsigned int i, j;
    for (i=0; i<size(); ++i)
    {
      if (((j=left(i))<size()) && interface_.greater(entry(i), entry(j))) 
      {
Jan Möbius's avatar
Jan Möbius committed
247
248
        omerr() << "Heap condition violated\n";
        ok=false;
Jan Möbius's avatar
Jan Möbius committed
249
250
251
      }
      if (((j=right(i))<size()) && interface_.greater(entry(i), entry(j)))
      {
Jan Möbius's avatar
Jan Möbius committed
252
253
        omerr() << "Heap condition violated\n";
        ok=false;
Jan Möbius's avatar
Jan Möbius committed
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
      }
    }
    return ok;
  }

protected:  
  /// Instance of HeapInterface
  HeapInterface interface_;

private:
  // typedef
  typedef std::vector<HeapEntry> HeapVector;

  
  /// Upheap. Establish heap property.
Jan Möbius's avatar
Jan Möbius committed
269
  void upheap(size_t _idx);
Jan Möbius's avatar
Jan Möbius committed
270
271
272

  
  /// Downheap. Establish heap property.
Jan Möbius's avatar
Jan Möbius committed
273
  void downheap(size_t _idx);
Jan Möbius's avatar
Jan Möbius committed
274
275
276

  
  /// Get the entry at index _idx
Jan Möbius's avatar
Jan Möbius committed
277
  inline HeapEntry entry(size_t _idx) const
Jan Möbius's avatar
Jan Möbius committed
278
279
280
281
282
283
284
  {
    assert(_idx < size());
    return (Base::operator[](_idx));
  }

  
  /// Set entry _h to index _idx and update _h's heap position.
Jan Möbius's avatar
Jan Möbius committed
285
  inline void entry(size_t _idx, HeapEntry _h)
Jan Möbius's avatar
Jan Möbius committed
286
287
288
289
290
291
292
293
  {
    assert(_idx < size());
    Base::operator[](_idx) = _h;
    interface_.set_heap_position(_h, _idx);
  }

  
  /// Get parent's index
Jan Möbius's avatar
Jan Möbius committed
294
  inline size_t parent(size_t _i) { return (_i-1)>>1; }
Jan Möbius's avatar
Jan Möbius committed
295
  /// Get left child's index
Jan Möbius's avatar
Jan Möbius committed
296
  inline size_t left(size_t _i)   { return (_i<<1)+1; }
Jan Möbius's avatar
Jan Möbius committed
297
  /// Get right child's index
Jan Möbius's avatar
Jan Möbius committed
298
  inline size_t right(size_t _i)  { return (_i<<1)+2; }
Jan Möbius's avatar
Jan Möbius committed
299
300
301
302
303
304
305
306
307
308
309
310

};




//== IMPLEMENTATION ========================================================== 


template <class HeapEntry, class HeapInterface>
void
HeapT<HeapEntry, HeapInterface>::
Jan Möbius's avatar
Jan Möbius committed
311
upheap(size_t _idx)
Jan Möbius's avatar
Jan Möbius committed
312
313
{
  HeapEntry     h = entry(_idx);
Jan Möbius's avatar
Jan Möbius committed
314
  size_t        parentIdx;
Jan Möbius's avatar
Jan Möbius committed
315

Jan Möbius's avatar
Jan Möbius committed
316
  while ((_idx>0) && interface_.less(h, entry(parentIdx=parent(_idx))))
Jan Möbius's avatar
Jan Möbius committed
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
  {
    entry(_idx, entry(parentIdx));
    _idx = parentIdx;    
  }
  
  entry(_idx, h);
}
  

//-----------------------------------------------------------------------------

  
template <class HeapEntry, class HeapInterface>
void
HeapT<HeapEntry, HeapInterface>::
Jan Möbius's avatar
Jan Möbius committed
332
downheap(size_t _idx)
Jan Möbius's avatar
Jan Möbius committed
333
334
{
  HeapEntry     h = entry(_idx);
Jan Möbius's avatar
Jan Möbius committed
335
336
  size_t        childIdx;
  size_t        s = size();
Jan Möbius's avatar
Jan Möbius committed
337
338
339
340
341
342
  
  while(_idx < s)
  {
    childIdx = left(_idx);
    if (childIdx >= s) break;
    
Jan Möbius's avatar
Jan Möbius committed
343
    if ((childIdx + 1 < s) && (interface_.less(entry(childIdx + 1), entry(childIdx))))
Jan Möbius's avatar
Jan Möbius committed
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
      ++childIdx;
    
    if (interface_.less(h, entry(childIdx))) break;

    entry(_idx, entry(childIdx));
    _idx = childIdx;
  }  

  entry(_idx, h);
}


//=============================================================================
} // END_NS_UTILS
} // END_NS_OPENMESH
//=============================================================================
#endif // OSG_HEAP_HH defined
//=============================================================================