summaryrefslogtreecommitdiff
path: root/agg/inc/agg_array.h
blob: 2970181c4510ac0c1bc772e27340ff81e56eba65 (plain)
1
2
3
4
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
41
42
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
85
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
114
115
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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
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
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.3
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
//          mcseemagg@yahoo.com
//          http://www.antigrain.com
//----------------------------------------------------------------------------
#ifndef AGG_ARRAY_INCLUDED
#define AGG_ARRAY_INCLUDED

#include <stddef.h>
#include <string.h>
#include "agg_basics.h"

namespace agg
{



    //-------------------------------------------------------pod_array_adaptor
    template<class T> class pod_array_adaptor
    {
    public:
        typedef T value_type;
        pod_array_adaptor(T* array, unsigned _size) :
            m_array(array), m_size(_size) {}

        unsigned size() const { return m_size; }
        const T& operator [] (unsigned idx) const { return m_array[idx]; }
              T& operator [] (unsigned idx)       { return m_array[idx]; }
    private:
        T*       m_array;
        unsigned m_size;
    };



    //---------------------------------------------------------pod_auto_array
    template<class T, unsigned Size> class pod_auto_array
    {
    public:
        typedef T value_type;
        typedef pod_auto_array<T, Size> self_type;

        pod_auto_array() {}
        explicit pod_auto_array(const T* c)
        {
            memcpy(m_array, c, sizeof(T) * Size);
        }

        const self_type& operator = (const T* c)
        {
            memcpy(m_array, c, sizeof(T) * Size);
            return *this;
        }

        static unsigned size() { return Size; }
        const T& operator [] (unsigned i) const { return m_array[i]; }
              T& operator [] (unsigned i)       { return m_array[i]; }
    private:
        T m_array[Size];
    };





    //---------------------------------------------------------------pod_array
    // A simple class template to store Plain Old Data, a vector
    // of a fixed size. The data is continous in memory
    //------------------------------------------------------------------------
    template<class T> class pod_array
    {
    public:
        typedef T value_type;

        ~pod_array() { delete [] m_array; }
        pod_array() : m_size(0), m_capacity(0), m_array(0) {}
        pod_array(unsigned cap, unsigned extra_tail=0);

        // Copying
        pod_array(const pod_array<T>&);
        const pod_array<T>& operator = (const pod_array<T>&);

        unsigned capacity() const { return m_capacity; }
        void capacity(unsigned cap, unsigned extra_tail=0);

        void resize(unsigned new_size);

        void add(const T& v)  { m_array[m_size++] = v; }
        void inc_size(unsigned _size) { m_size += _size; }
        unsigned size()      const { return m_size; }
        unsigned byte_size() const { return m_size * sizeof(T); }
        void serialize(int8u* ptr) const;
        void deserialize(const int8u* data, unsigned byte_size);
        const T& operator [] (unsigned idx) const { return m_array[idx]; }
              T& operator [] (unsigned idx)       { return m_array[idx]; }

        void remove_all()         { m_size = 0; }
        void cut_at(unsigned num) { if(num < m_size) m_size = num; }

    private:
        unsigned m_size;
        unsigned m_capacity;
        T*       m_array;
    };

    //------------------------------------------------------------------------
    template<class T>
    void pod_array<T>::capacity(unsigned cap, unsigned extra_tail)
    {
        m_size = 0;
        if(cap > m_capacity)
        {
            delete [] m_array;
            m_capacity = cap + extra_tail;
            m_array = m_capacity ? new T [m_capacity] : 0;
        }
    }

    //------------------------------------------------------------------------
    template<class T>
    void pod_array<T>::resize(unsigned new_size)
    {
        if(new_size > m_size)
        {
            if(new_size > m_capacity)
            {
                T* data = new T[new_size];
                memcpy(data, m_array, m_size * sizeof(T));
                delete [] m_array;
                m_array = data;
            }
        }
        else
        {
            m_size = new_size;
        }
    }

    //------------------------------------------------------------------------
    template<class T> pod_array<T>::pod_array(unsigned cap, unsigned extra_tail) :
        m_size(cap), m_capacity(cap + extra_tail), m_array(new T[m_capacity]) {}

    //------------------------------------------------------------------------
    template<class T> pod_array<T>::pod_array(const pod_array<T>& v) :
        m_size(v.m_size),
        m_capacity(v.m_capacity),
        m_array(v.m_capacity ? new T [v.m_capacity] : 0)
    {
        memcpy(m_array, v.m_array, sizeof(T) * v.m_size);
    }

    //------------------------------------------------------------------------
    template<class T> const pod_array<T>&
    pod_array<T>::operator = (const pod_array<T>&v)
    {
        capacity(v.m_capacity);
        if(v.m_size) memcpy(m_array, v.m_array, sizeof(T) * v.m_size);
        return *this;
    }

    //------------------------------------------------------------------------
    template<class T> void pod_array<T>::serialize(int8u* ptr) const
    {
        if(m_size) memcpy(ptr, m_array, m_size * sizeof(T));
    }

    //------------------------------------------------------------------------
    template<class T>
    void pod_array<T>::deserialize(const int8u* data, unsigned _byte_size)
    {
        _byte_size /= sizeof(T);
        capacity(_byte_size);
        if(_byte_size) memcpy(m_array, data, _byte_size * sizeof(T));
    }





    //---------------------------------------------------------------pod_deque
    // A simple class template to store Plain Old Data, similar to std::deque
    // It doesn't reallocate memory but instead, uses blocks of data of size
    // of (1 << S), that is, power of two. The data is NOT contiguous in memory,
    // so the only valid access method is operator [] or curr(), prev(), next()
    //
    // There reallocs occure only when the pool of pointers to blocks needs
    // to be extended (it happens very rarely). You can control the value
    // of increment to reallocate the pointer buffer. See the second constructor.
    // By default, the incremeent value equals (1 << S), i.e., the block size.
    //------------------------------------------------------------------------
    template<class T, unsigned S=6> class pod_deque
    {
    public:
        enum
        {
            block_shift = S,
            block_size  = 1 << block_shift,
            block_mask  = block_size - 1
        };

        typedef T value_type;

        ~pod_deque();
        pod_deque();
        pod_deque(unsigned block_ptr_inc);

        // Copying
        pod_deque(const pod_deque<T, S>& v);
        const pod_deque<T, S>& operator = (const pod_deque<T, S>& v);

        void remove_all() { m_size = 0; }
        void free_all() { free_tail(0); }
        void free_tail(unsigned size);
        void add(const T& val);
        void modify_last(const T& val);
        void remove_last();

        int allocate_continuous_block(unsigned num_elements);

        void add_array(const T* ptr, unsigned num_elem)
        {
            while(num_elem--)
            {
                add(*ptr++);
            }
        }

        template<class DataAccessor> void add_data(DataAccessor& data)
        {
            while(data.size())
            {
                add(*data);
                ++data;
            }
        }

        void cut_at(unsigned _size)
        {
            if(_size < m_size) m_size = _size;
        }

        unsigned size() const { return m_size; }

        const T& operator [] (unsigned idx) const
        {
            return m_blocks[idx >> block_shift][idx & block_mask];
        }

        T& operator [] (unsigned idx)
        {
            return m_blocks[idx >> block_shift][idx & block_mask];
        }

        const T& curr(unsigned idx) const
        {
            return (*this)[idx];
        }

        T& curr(unsigned idx)
        {
            return (*this)[idx];
        }

        const T& prev(unsigned idx) const
        {
            return (*this)[(idx + m_size - 1) % m_size];
        }

        T& prev(unsigned idx)
        {
            return (*this)[(idx + m_size - 1) % m_size];
        }

        const T& next(unsigned idx) const
        {
            return (*this)[(idx + 1) % m_size];
        }

        T& next(unsigned idx)
        {
            return (*this)[(idx + 1) % m_size];
        }

        const T& last() const
        {
            return (*this)[m_size - 1];
        }

        T& last()
        {
            return (*this)[m_size - 1];
        }

        unsigned byte_size() const;
        void serialize(int8u* ptr) const;
        void deserialize(const int8u* data, unsigned byte_size);
        void deserialize(unsigned start, const T& empty_val,
                         const int8u* data, unsigned byte_size);

        template<class ByteAccessor>
        void deserialize(ByteAccessor data)
        {
            remove_all();
            unsigned elem_size = data.size() / sizeof(T);

            for(unsigned i = 0; i < elem_size; ++i)
            {
                int8u* ptr = (int8u*)data_ptr();
                for(unsigned j = 0; j < sizeof(T); ++j)
                {
                    *ptr++ = *data;
                    ++data;
                }
                ++m_size;
            }
        }

        template<class ByteAccessor>
        void deserialize(unsigned start, const T& empty_val, ByteAccessor data)
        {
            while(m_size < start)
            {
                add(empty_val);
            }

            unsigned elem_size = data.size() / sizeof(T);
            for(unsigned i = 0; i < elem_size; ++i)
            {
                int8u* ptr;
                if(start + i < m_size)
                {
                    ptr = (int8u*)(&((*this)[start + i]));
                }
                else
                {
                    ptr = (int8u*)data_ptr();
                    ++m_size;
                }
                for(unsigned j = 0; j < sizeof(T); ++j)
                {
                    *ptr++ = *data;
                    ++data;
                }
            }
        }

        const T* block(unsigned nb) const { return m_blocks[nb]; }

    private:
        void allocate_block(unsigned nb);
        T*   data_ptr();

        unsigned        m_size;
        unsigned        m_num_blocks;
        unsigned        m_max_blocks;
        T**             m_blocks;
        unsigned        m_block_ptr_inc;
    };


    //------------------------------------------------------------------------
    template<class T, unsigned S> pod_deque<T, S>::~pod_deque()
    {
        if(m_num_blocks)
        {
            T** blk = m_blocks + m_num_blocks - 1;
            while(m_num_blocks--)
            {
                delete [] *blk;
                --blk;
            }
            delete [] m_blocks;
        }
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::free_tail(unsigned _size)
    {
        if(_size < m_size)
        {
            unsigned nb = (_size + block_mask) >> block_shift;
            while(m_num_blocks > nb)
            {
                delete [] m_blocks[--m_num_blocks];
            }
            m_size = _size;
        }
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S> pod_deque<T, S>::pod_deque() :
        m_size(0),
        m_num_blocks(0),
        m_max_blocks(0),
        m_blocks(0),
        m_block_ptr_inc(block_size)
    {
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    pod_deque<T, S>::pod_deque(unsigned block_ptr_inc) :
        m_size(0),
        m_num_blocks(0),
        m_max_blocks(0),
        m_blocks(0),
        m_block_ptr_inc(block_ptr_inc)
    {
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    pod_deque<T, S>::pod_deque(const pod_deque<T, S>& v) :
        m_size(v.m_size),
        m_num_blocks(v.m_num_blocks),
        m_max_blocks(v.m_max_blocks),
        m_blocks(v.m_max_blocks ? new T* [v.m_max_blocks] : 0),
        m_block_ptr_inc(v.m_block_ptr_inc)
    {
        unsigned i;
        for(i = 0; i < v.m_num_blocks; ++i)
        {
            m_blocks[i] = new T [block_size];
            memcpy(m_blocks[i], v.m_blocks[i], block_size * sizeof(T));
        }
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    const pod_deque<T, S>& pod_deque<T, S>::operator = (const pod_deque<T, S>& v)
    {
        unsigned i;
        for(i = m_num_blocks; i < v.m_num_blocks; ++i)
        {
            allocate_block(i);
        }
        for(i = 0; i < v.m_num_blocks; ++i)
        {
            memcpy(m_blocks[i], v.m_blocks[i], block_size * sizeof(T));
        }
        m_size = v.m_size;
        return *this;
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::allocate_block(unsigned nb)
    {
        if(nb >= m_max_blocks)
        {
            T** new_blocks = new T* [m_max_blocks + m_block_ptr_inc];

            if(m_blocks)
            {
                memcpy(new_blocks,
                       m_blocks,
                       m_num_blocks * sizeof(T*));

                delete [] m_blocks;
            }
            m_blocks = new_blocks;
            m_max_blocks += m_block_ptr_inc;
        }
        m_blocks[nb] = new T [block_size];
        m_num_blocks++;
    }



    //------------------------------------------------------------------------
    template<class T, unsigned S>
    inline T* pod_deque<T, S>::data_ptr()
    {
        unsigned nb = m_size >> block_shift;
        if(nb >= m_num_blocks)
        {
            allocate_block(nb);
        }
        return m_blocks[nb] + (m_size & block_mask);
    }



    //------------------------------------------------------------------------
    template<class T, unsigned S>
    inline void pod_deque<T, S>::add(const T& val)
    {
        *data_ptr() = val;
        ++m_size;
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    inline void pod_deque<T, S>::remove_last()
    {
        if(m_size) --m_size;
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::modify_last(const T& val)
    {
        remove_last();
        add(val);
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    int pod_deque<T, S>::allocate_continuous_block(unsigned num_elements)
    {
        if(num_elements < block_size)
        {
            data_ptr(); // Allocate initial block if necessary
            unsigned rest = block_size - (m_size & block_mask);
            unsigned index;
            if(num_elements <= rest)
            {
                // The rest of the block is good, we can use it
                //-----------------
                index = m_size;
                m_size += num_elements;
                return index;
            }

            // New block
            //---------------
            m_size += rest;
            data_ptr();
            index = m_size;
            m_size += num_elements;
            return index;
        }
        return -1; // Impossible to allocate
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    unsigned pod_deque<T, S>::byte_size() const
    {
        return m_size * sizeof(T);
    }


    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::serialize(int8u* ptr) const
    {
        unsigned i;
        for(i = 0; i < m_size; i++)
        {
            memcpy(ptr, &(*this)[i], sizeof(T));
            ptr += sizeof(T);
        }
    }

    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::deserialize(const int8u* data, unsigned _byte_size)
    {
        remove_all();
        _byte_size /= sizeof(T);
        for(unsigned i = 0; i < _byte_size; ++i)
        {
            T* ptr = data_ptr();
            memcpy(ptr, data, sizeof(T));
            ++m_size;
            data += sizeof(T);
        }
    }


    // Replace or add a number of elements starting from "start" position
    //------------------------------------------------------------------------
    template<class T, unsigned S>
    void pod_deque<T, S>::deserialize(unsigned start, const T& empty_val,
                                      const int8u* data, unsigned _byte_size)
    {
        while(m_size < start)
        {
            add(empty_val);
        }

        _byte_size /= sizeof(T);
        for(unsigned i = 0; i < _byte_size; ++i)
        {
            if(start + i < m_size)
            {
                memcpy(&((*this)[start + i]), data, sizeof(T));
            }
            else
            {
                T* ptr = data_ptr();
                memcpy(ptr, data, sizeof(T));
                ++m_size;
            }
            data += sizeof(T);
        }
    }


    //-----------------------------------------------------------pod_allocator
    // Allocator for arbitrary POD data. Most usable in different cache
    // systems for efficient memory allocations.
    // Memory is allocated with blocks of fixed size ("block_size" in
    // the constructor). If required size exceeds the block size the allocator
    // creates a new block of the required size. However, the most efficient
    // use is when the average reqired size is much less than the block size.
    //------------------------------------------------------------------------
    class pod_allocator
    {
    public:
        void remove_all()
        {
            if(m_num_blocks)
            {
                int8u** blk = m_blocks + m_num_blocks - 1;
                while(m_num_blocks--)
                {
                    delete [] *blk;
                    --blk;
                }
                delete [] m_blocks;
            }
            m_num_blocks = 0;
            m_max_blocks = 0;
            m_blocks = 0;
            m_buf_ptr = 0;
            m_rest = 0;
        }

        ~pod_allocator()
        {
            remove_all();
        }

        pod_allocator(unsigned block_size, unsigned block_ptr_inc=256-8) :
            m_block_size(block_size),
            m_block_ptr_inc(block_ptr_inc),
            m_num_blocks(0),
            m_max_blocks(0),
            m_blocks(0),
            m_buf_ptr(0),
            m_rest(0)
        {
        }


        int8u* allocate(unsigned size, unsigned alignment=1)
        {
            if(size == 0) return 0;
            if(size <= m_rest)
            {
                int8u* ptr = m_buf_ptr;
                if(alignment > 1)
                {
                    unsigned align = (alignment - unsigned((size_t)ptr) % alignment) % alignment;
                    size += align;
                    ptr += align;
                    if(size <= m_rest)
                    {
                        m_rest -= size;
                        m_buf_ptr += size;
                        return ptr;
                    }
                    allocate_block(size);
                    return allocate(size - align, alignment);
                }
                m_rest -= size;
                m_buf_ptr += size;
                return ptr;
            }
            allocate_block(size + alignment - 1);
            return allocate(size, alignment);
        }


    private:
        void allocate_block(unsigned size)
        {
            if(size < m_block_size) size = m_block_size;
            if(m_num_blocks >= m_max_blocks)
            {
                int8u** new_blocks = new int8u* [m_max_blocks + m_block_ptr_inc];

                if(m_blocks)
                {
                    memcpy(new_blocks,
                           m_blocks,
                           m_num_blocks * sizeof(int8u*));

                    delete [] m_blocks;
                }
                m_blocks = new_blocks;
                m_max_blocks += m_block_ptr_inc;
            }
            m_blocks[m_num_blocks] = m_buf_ptr = new int8u [size];
            m_num_blocks++;
            m_rest = size;
        }

        unsigned m_block_size;
        unsigned m_block_ptr_inc;
        unsigned m_num_blocks;
        unsigned m_max_blocks;
        int8u**  m_blocks;
        int8u*   m_buf_ptr;
        unsigned m_rest;
    };








    //------------------------------------------------------------------------
    enum
    {
        quick_sort_threshold = 9
    };


    //-----------------------------------------------------------swap_elements
    template<class T> inline void swap_elements(T& a, T& b)
    {
        T temp = a;
        a = b;
        b = temp;
    }


    //--------------------------------------------------------------quick_sort
    template<class Array, class Less>
    void quick_sort(Array& arr, Less less)
    {
        if(arr.size() < 2) return;

        typename Array::value_type* e1;
        typename Array::value_type* e2;

        int  stack[80];
        int* top = stack;
        int  limit = arr.size();
        int  base = 0;

        for(;;)
        {
            int len = limit - base;

            int i;
            int j;
            int pivot;

            if(len > quick_sort_threshold)
            {
                // we use base + len/2 as the pivot
                pivot = base + len / 2;
                swap_elements(arr[base], arr[pivot]);

                i = base + 1;
                j = limit - 1;

                // now ensure that *i <= *base <= *j
                e1 = &(arr[j]);
                e2 = &(arr[i]);
                if(less(*e1, *e2)) swap_elements(*e1, *e2);

                e1 = &(arr[base]);
                e2 = &(arr[i]);
                if(less(*e1, *e2)) swap_elements(*e1, *e2);

                e1 = &(arr[j]);
                e2 = &(arr[base]);
                if(less(*e1, *e2)) swap_elements(*e1, *e2);

                for(;;)
                {
                    do i++; while( less(arr[i], arr[base]) );
                    do j--; while( less(arr[base], arr[j]) );

                    if( i > j )
                    {
                        break;
                    }

                    swap_elements(arr[i], arr[j]);
                }

                swap_elements(arr[base], arr[j]);

                // now, push the largest sub-array
                if(j - base > limit - i)
                {
                    top[0] = base;
                    top[1] = j;
                    base   = i;
                }
                else
                {
                    top[0] = i;
                    top[1] = limit;
                    limit  = j;
                }
                top += 2;
            }
            else
            {
                // the sub-array is small, perform insertion sort
                j = base;
                i = j + 1;

                for(; i < limit; j = i, i++)
                {
                    for(; less(*(e1 = &(arr[j + 1])), *(e2 = &(arr[j]))); j--)
                    {
                        swap_elements(*e1, *e2);
                        if(j == base)
                        {
                            break;
                        }
                    }
                }
                if(top > stack)
                {
                    top  -= 2;
                    base  = top[0];
                    limit = top[1];
                }
                else
                {
                    break;
                }
            }
        }
    }




    //------------------------------------------------------remove_duplicates
    // Remove duplicates from a sorted array. It doesn't cut the the
    // tail of the array, it just returns the number of remaining elements.
    //-----------------------------------------------------------------------
    template<class Array, class Equal>
    unsigned remove_duplicates(Array& arr, Equal equal)
    {
        if(arr.size() < 2) return arr.size();

        unsigned i, j;
        for(i = 1, j = 1; i < arr.size(); i++)
        {
            typename Array::value_type& e = arr[i];
            if(!equal(e, arr[i - 1]))
            {
                arr[j++] = e;
            }
        }
        return j;
    }




}

#endif