aboutsummaryrefslogtreecommitdiff
path: root/libstdc++-v3/include/ext/pb_ds/detail/binary_heap_/resize_policy.hpp
blob: c6021a998041fb969a08e3f2d072dd059df834a7 (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
// -*- C++ -*-

// Copyright (C) 2005, 2006 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 2, or (at your option) any later
// version.

// This library 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
// General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.

// As a special exception, you may use this file as part of a free
// software library without restriction.  Specifically, 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 General Public
// License.  This exception does not however invalidate any other
// reasons why the executable file might be covered by the GNU General
// Public License.

// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.

// Permission to use, copy, modify, sell, and distribute this software
// is hereby granted without fee, provided that the above copyright
// notice appears in all copies, and that both that copyright notice
// and this permission notice appear in supporting documentation. None
// of the above authors, nor IBM Haifa Research Laboratories, make any
// representation about the suitability of this software for any
// purpose. It is provided "as is" without express or implied
// warranty.

/**
 * @file resize_policy.hpp
 * Contains an implementation class for a binary_heap.
 */

#ifndef PB_DS_BINARY_HEAP_RESIZE_POLICY_HPP
#define PB_DS_BINARY_HEAP_RESIZE_POLICY_HPP

#include <debug/debug.h>

namespace pb_ds
{
  namespace detail
  {

#define PB_DS_CLASS_T_DEC template<typename Size_Type>

#define PB_DS_CLASS_C_DEC resize_policy<Size_Type>

    template<typename Size_Type>
    class resize_policy
    {
    public:
      typedef Size_Type size_type;

      enum
	{
	  min_size = 16
	};

    public:
      inline
      resize_policy();

      inline void
      swap(PB_DS_CLASS_C_DEC& other);

      inline bool
      resize_needed_for_grow(size_type size) const;

      inline bool
      resize_needed_for_shrink(size_type size) const;

      inline bool
      grow_needed(size_type size) const;

      inline bool
      shrink_needed(size_type size) const;

      inline size_type
      get_new_size_for_grow() const;

      inline size_type
      get_new_size_for_shrink() const;

      size_type
      get_new_size_for_arbitrary(size_type size) const;

      inline void
      notify_grow_resize();

      inline void
      notify_shrink_resize();

      void
      notify_arbitrary(size_type actual_size);

#ifdef _GLIBCXX_DEBUG
      void
      assert_valid() const;
#endif 

#ifdef PB_DS_BINARY_HEAP_TRACE_
      void
      trace() const;
#endif 

    private:
      enum
	{
	  ratio = 8,
	  factor = 2
	};

    private:
      size_type m_next_shrink_size;
      size_type m_next_grow_size;
    };

    PB_DS_CLASS_T_DEC
    inline
    PB_DS_CLASS_C_DEC::
    resize_policy() :
      m_next_shrink_size(0),
      m_next_grow_size(min_size)
    { _GLIBCXX_DEBUG_ONLY(assert_valid();) }

    PB_DS_CLASS_T_DEC
    inline void
    PB_DS_CLASS_C_DEC::
    swap(PB_DS_CLASS_C_DEC& other)
    {
      std::swap(m_next_shrink_size, other.m_next_shrink_size);
      std::swap(m_next_grow_size, other.m_next_grow_size);
    }

    PB_DS_CLASS_T_DEC
    inline bool
    PB_DS_CLASS_C_DEC::
    resize_needed_for_grow(size_type size) const
    {
      _GLIBCXX_DEBUG_ASSERT(size <= m_next_grow_size);
      return size == m_next_grow_size;
    }

    PB_DS_CLASS_T_DEC
    inline bool
    PB_DS_CLASS_C_DEC::
    resize_needed_for_shrink(size_type size) const
    {
      _GLIBCXX_DEBUG_ASSERT(size <= m_next_grow_size);
      return size == m_next_shrink_size;
    }

    PB_DS_CLASS_T_DEC
    inline typename PB_DS_CLASS_C_DEC::size_type
    PB_DS_CLASS_C_DEC::
    get_new_size_for_grow() const
    { return m_next_grow_size*  factor; }

    PB_DS_CLASS_T_DEC
    inline typename PB_DS_CLASS_C_DEC::size_type
    PB_DS_CLASS_C_DEC::
    get_new_size_for_shrink() const
    {
      const size_type half_size = m_next_grow_size / factor;
      return std::max(static_cast<size_type>(min_size), half_size);
    }

    PB_DS_CLASS_T_DEC
    inline typename PB_DS_CLASS_C_DEC::size_type
    PB_DS_CLASS_C_DEC::
    get_new_size_for_arbitrary(size_type size) const
    {
      size_type ret = min_size;
      while (ret < size)
	ret *= factor;
      return ret;
    }

    PB_DS_CLASS_T_DEC
    inline void
    PB_DS_CLASS_C_DEC::
    notify_grow_resize()
    {
      _GLIBCXX_DEBUG_ONLY(assert_valid();)
      _GLIBCXX_DEBUG_ASSERT(m_next_grow_size >= min_size);
      m_next_grow_size *= factor;
      m_next_shrink_size = m_next_grow_size / ratio;
      _GLIBCXX_DEBUG_ONLY(assert_valid();)
    }

    PB_DS_CLASS_T_DEC
    inline void
    PB_DS_CLASS_C_DEC::
    notify_shrink_resize()
    {
      _GLIBCXX_DEBUG_ONLY(assert_valid();)
      m_next_shrink_size /= factor;
      if (m_next_shrink_size == 1)
	m_next_shrink_size = 0;

      m_next_grow_size =
	std::max(m_next_grow_size / factor, static_cast<size_type>(min_size));
      _GLIBCXX_DEBUG_ONLY(assert_valid();)
    }

    PB_DS_CLASS_T_DEC
    inline void
    PB_DS_CLASS_C_DEC::
    notify_arbitrary(size_type actual_size)
    {
      m_next_grow_size = actual_size;
      m_next_shrink_size = m_next_grow_size / ratio;
      _GLIBCXX_DEBUG_ONLY(assert_valid();)
    }

#ifdef _GLIBCXX_DEBUG
    PB_DS_CLASS_T_DEC
    void
    PB_DS_CLASS_C_DEC::
    assert_valid() const
    {
      _GLIBCXX_DEBUG_ASSERT(m_next_shrink_size == 0 ||
		       m_next_shrink_size*  ratio == m_next_grow_size);

      _GLIBCXX_DEBUG_ASSERT(m_next_grow_size >= min_size);
    }
#endif 

#ifdef PB_DS_BINARY_HEAP_TRACE_
    PB_DS_CLASS_T_DEC
    void
    PB_DS_CLASS_C_DEC::
    trace() const
    {
      std::cerr << "shrink = " << m_next_shrink_size <<
	" grow = " << m_next_grow_size << std::endl;
    }
#endif 

#undef PB_DS_CLASS_T_DEC
#undef PB_DS_CLASS_C_DEC

} // namespace detail
} // namespace pb_ds

#endif