libstdc++

hash_policy.hpp
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1 // -*- C++ -*-
2
3 // Copyright (C) 2005-2013 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the terms
7 // of the GNU General Public License as published by the Free Software
8 // Foundation; either version 3, or (at your option) any later
9 // version.
10
11 // This library is distributed in the hope that it will be useful, but
12 // WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 // General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
26
27 // Permission to use, copy, modify, sell, and distribute this software
28 // is hereby granted without fee, provided that the above copyright
29 // notice appears in all copies, and that both that copyright notice
30 // and this permission notice appear in supporting documentation. None
31 // of the above authors, nor IBM Haifa Research Laboratories, make any
32 // representation about the suitability of this software for any
33 // purpose. It is provided "as is" without express or implied
34 // warranty.
35
36 /**
37 * @file hash_policy.hpp
38 * Contains hash-related policies.
39 */
40
41 #ifndef PB_DS_HASH_POLICY_HPP
42 #define PB_DS_HASH_POLICY_HPP
43
44 #include <bits/c++config.h>
45 #include <algorithm>
46 #include <vector>
47 #include <cmath>
48 #include <ext/pb_ds/exception.hpp>
49 #include <ext/pb_ds/detail/type_utils.hpp>
50 #include <ext/pb_ds/detail/hash_fn/mask_based_range_hashing.hpp>
51 #include <ext/pb_ds/detail/hash_fn/mod_based_range_hashing.hpp>
52 #include <ext/pb_ds/detail/resize_policy/hash_load_check_resize_trigger_size_base.hpp>
53
54 namespace __gnu_pbds
55 {
56 #define PB_DS_CLASS_T_DEC template<typename Size_Type>
57 #define PB_DS_CLASS_C_DEC linear_probe_fn<Size_Type>
58
59 /// A probe sequence policy using fixed increments.
60 template<typename Size_Type = std::size_t>
61 class linear_probe_fn
62 {
63 public:
64 typedef Size_Type size_type;
65
66 void
67 swap(PB_DS_CLASS_C_DEC& other);
68
69 protected:
70 /// Returns the i-th offset from the hash value.
71 inline size_type
72 operator()(size_type i) const;
73 };
74
75 #include <ext/pb_ds/detail/hash_fn/linear_probe_fn_imp.hpp>
76
77 #undef PB_DS_CLASS_T_DEC
78 #undef PB_DS_CLASS_C_DEC
79
80 #define PB_DS_CLASS_T_DEC template<typename Size_Type>
81 #define PB_DS_CLASS_C_DEC quadratic_probe_fn<Size_Type>
82
83 /// A probe sequence policy using square increments.
84 template<typename Size_Type = std::size_t>
85 class quadratic_probe_fn
86 {
87 public:
88 typedef Size_Type size_type;
89
90 void
91 swap(PB_DS_CLASS_C_DEC& other);
92
93 protected:
94 /// Returns the i-th offset from the hash value.
95 inline size_type
96 operator()(size_type i) const;
97 };
98
99 #include <ext/pb_ds/detail/hash_fn/quadratic_probe_fn_imp.hpp>
100
101 #undef PB_DS_CLASS_T_DEC
102 #undef PB_DS_CLASS_C_DEC
103
104 #define PB_DS_CLASS_T_DEC template<typename Size_Type>
105 #define PB_DS_CLASS_C_DEC direct_mask_range_hashing<Size_Type>
106
107 /// A mask range-hashing class (uses a bitmask).
108 template<typename Size_Type = std::size_t>
109 class direct_mask_range_hashing
110 : public detail::mask_based_range_hashing<Size_Type>
111 {
112 private:
113 typedef detail::mask_based_range_hashing<Size_Type> mask_based_base;
114
115 public:
116 typedef Size_Type size_type;
117
118 void
119 swap(PB_DS_CLASS_C_DEC& other);
120
121 protected:
122 void
123 notify_resized(size_type size);
124
125 /// Transforms the __hash value hash into a ranged-hash value
126 /// (using a bit-mask).
127 inline size_type
128 operator()(size_type hash) const;
129 };
130
131 #include <ext/pb_ds/detail/hash_fn/direct_mask_range_hashing_imp.hpp>
132
133 #undef PB_DS_CLASS_T_DEC
134 #undef PB_DS_CLASS_C_DEC
135
136 #define PB_DS_CLASS_T_DEC template<typename Size_Type>
137 #define PB_DS_CLASS_C_DEC direct_mod_range_hashing<Size_Type>
138
139 /// A mod range-hashing class (uses the modulo function).
140 template<typename Size_Type = std::size_t>
141 class direct_mod_range_hashing
142 : public detail::mod_based_range_hashing<Size_Type>
143 {
144 public:
145 typedef Size_Type size_type;
146
147 void
148 swap(PB_DS_CLASS_C_DEC& other);
149
150 protected:
151 void
152 notify_resized(size_type size);
153
154 /// Transforms the __hash value hash into a ranged-hash value
155 /// (using a modulo operation).
156 inline size_type
157 operator()(size_type hash) const;
158
159 private:
160 typedef detail::mod_based_range_hashing<size_type> mod_based_base;
161 };
162
163 #include <ext/pb_ds/detail/hash_fn/direct_mod_range_hashing_imp.hpp>
164
165 #undef PB_DS_CLASS_T_DEC
166 #undef PB_DS_CLASS_C_DEC
167
168 #define PB_DS_CLASS_T_DEC template<bool External_Load_Access, typename Size_Type>
169 #define PB_DS_CLASS_C_DEC hash_load_check_resize_trigger<External_Load_Access, Size_Type>
170 #define PB_DS_SIZE_BASE_C_DEC detail::hash_load_check_resize_trigger_size_base<Size_Type, External_Load_Access>
171
172 /// A resize trigger policy based on a load check. It keeps the
173 /// load factor between some load factors load_min and load_max.
174 template<bool External_Load_Access = false, typename Size_Type = std::size_t>
175 class hash_load_check_resize_trigger : private PB_DS_SIZE_BASE_C_DEC
176 {
177 public:
178 typedef Size_Type size_type;
179
180 enum
181 {
182 /// Specifies whether the load factor can be accessed
183 /// externally. The two options have different trade-offs in
184 /// terms of flexibility, genericity, and encapsulation.
185 external_load_access = External_Load_Access
186 };
187
188 /// Default constructor, or constructor taking load_min and
189 /// load_max load factors between which this policy will keep the
190 /// actual load.
191 hash_load_check_resize_trigger(float load_min = 0.125,
192 float load_max = 0.5);
193
194 void
195 swap(hash_load_check_resize_trigger& other);
196
197 virtual
198 ~hash_load_check_resize_trigger();
199
200 /// Returns a pair of the minimal and maximal loads, respectively.
201 inline std::pair<float, float>
202 get_loads() const;
203
204 /// Sets the loads through a pair of the minimal and maximal
205 /// loads, respectively.
206 void
207 set_loads(std::pair<float, float> load_pair);
208
209 protected:
210 inline void
211 notify_insert_search_start();
212
213 inline void
214 notify_insert_search_collision();
215
216 inline void
217 notify_insert_search_end();
218
219 inline void
220 notify_find_search_start();
221
222 inline void
223 notify_find_search_collision();
224
225 inline void
226 notify_find_search_end();
227
228 inline void
229 notify_erase_search_start();
230
231 inline void
232 notify_erase_search_collision();
233
234 inline void
235 notify_erase_search_end();
236
237 /// Notifies an element was inserted. The total number of entries
238 /// in the table is num_entries.
239 inline void
240 notify_inserted(size_type num_entries);
241
242 inline void
243 notify_erased(size_type num_entries);
244
245 /// Notifies the table was cleared.
246 void
247 notify_cleared();
248
249 /// Notifies the table was resized as a result of this object's
250 /// signifying that a resize is needed.
251 void
252 notify_resized(size_type new_size);
253
254 void
255 notify_externally_resized(size_type new_size);
256
257 inline bool
258 is_resize_needed() const;
259
260 inline bool
261 is_grow_needed(size_type size, size_type num_entries) const;
262
263 private:
264 virtual void
265 do_resize(size_type new_size);
266
267 typedef PB_DS_SIZE_BASE_C_DEC size_base;
268
269 #ifdef _GLIBCXX_DEBUG
270 void
271 assert_valid(const char* file, int line) const;
272 #endif
273
274 float m_load_min;
275 float m_load_max;
276 size_type m_next_shrink_size;
277 size_type m_next_grow_size;
278 bool m_resize_needed;
279 };
280
281 #include <ext/pb_ds/detail/resize_policy/hash_load_check_resize_trigger_imp.hpp>
282
283 #undef PB_DS_CLASS_T_DEC
284 #undef PB_DS_CLASS_C_DEC
285 #undef PB_DS_SIZE_BASE_C_DEC
286
287 #define PB_DS_CLASS_T_DEC template<bool External_Load_Access, typename Size_Type>
288 #define PB_DS_CLASS_C_DEC cc_hash_max_collision_check_resize_trigger<External_Load_Access, Size_Type>
289
290 /// A resize trigger policy based on collision checks. It keeps the
291 /// simulated load factor lower than some given load factor.
292 template<bool External_Load_Access = false, typename Size_Type = std::size_t>
293 class cc_hash_max_collision_check_resize_trigger
294 {
295 public:
296 typedef Size_Type size_type;
297
298 enum
299 {
300 /// Specifies whether the load factor can be accessed
301 /// externally. The two options have different trade-offs in
302 /// terms of flexibility, genericity, and encapsulation.
303 external_load_access = External_Load_Access
304 };
305
306 /// Default constructor, or constructor taking load, a __load
307 /// factor which it will attempt to maintain.
308 cc_hash_max_collision_check_resize_trigger(float load = 0.5);
309
310 void
311 swap(PB_DS_CLASS_C_DEC& other);
312
313 /// Returns the current load.
314 inline float
315 get_load() const;
316
317 /// Sets the load; does not resize the container.
318 void
319 set_load(float load);
320
321 protected:
322 /// Notifies an insert search started.
323 inline void
324 notify_insert_search_start();
325
326 /// Notifies a search encountered a collision.
327 inline void
328 notify_insert_search_collision();
329
330 /// Notifies a search ended.
331 inline void
332 notify_insert_search_end();
333
334 /// Notifies a find search started.
335 inline void
336 notify_find_search_start();
337
338 /// Notifies a search encountered a collision.
339 inline void
340 notify_find_search_collision();
341
342 /// Notifies a search ended.
343 inline void
344 notify_find_search_end();
345
346 /// Notifies an erase search started.
347 inline void
348 notify_erase_search_start();
349
350 /// Notifies a search encountered a collision.
351 inline void
352 notify_erase_search_collision();
353
354 /// Notifies a search ended.
355 inline void
356 notify_erase_search_end();
357
358 /// Notifies an element was inserted.
359 inline void
360 notify_inserted(size_type num_entries);
361
362 /// Notifies an element was erased.
363 inline void
364 notify_erased(size_type num_entries);
365
366 /// Notifies the table was cleared.
367 void
368 notify_cleared();
369
370 /// Notifies the table was resized as a result of this object's
371 /// signifying that a resize is needed.
372 void
373 notify_resized(size_type new_size);
374
375 /// Notifies the table was resized externally.
376 void
377 notify_externally_resized(size_type new_size);
378
379 /// Queries whether a resize is needed.
380 inline bool
381 is_resize_needed() const;
382
383 /// Queries whether a grow is needed. This method is called only
384 /// if this object indicated is needed.
385 inline bool
386 is_grow_needed(size_type size, size_type num_entries) const;
387
388 private:
389 void
390 calc_max_num_coll();
391
392 inline void
393 calc_resize_needed();
394
395 float m_load;
396 size_type m_size;
397 size_type m_num_col;
398 size_type m_max_col;
399 bool m_resize_needed;
400 };
401
402 #include <ext/pb_ds/detail/resize_policy/cc_hash_max_collision_check_resize_trigger_imp.hpp>
403
404 #undef PB_DS_CLASS_T_DEC
405 #undef PB_DS_CLASS_C_DEC
406
407 #define PB_DS_CLASS_T_DEC template<typename Size_Type>
408 #define PB_DS_CLASS_C_DEC hash_exponential_size_policy<Size_Type>
409
410 /// A size policy whose sequence of sizes form an exponential
411 /// sequence (typically powers of 2.
412 template<typename Size_Type = std::size_t>
413 class hash_exponential_size_policy
414 {
415 public:
416 typedef Size_Type size_type;
417
418 /// Default constructor, or onstructor taking a start_size, or
419 /// constructor taking a start size and grow_factor. The policy
420 /// will use the sequence of sizes start_size, start_size*
421 /// grow_factor, start_size* grow_factor^2, ...
422 hash_exponential_size_policy(size_type start_size = 8,
423 size_type grow_factor = 2);
424
425 void
426 swap(PB_DS_CLASS_C_DEC& other);
427
428 protected:
429 size_type
430 get_nearest_larger_size(size_type size) const;
431
432 size_type
433 get_nearest_smaller_size(size_type size) const;
434
435 private:
436 size_type m_start_size;
437 size_type m_grow_factor;
438 };
439
440 #include <ext/pb_ds/detail/resize_policy/hash_exponential_size_policy_imp.hpp>
441
442 #undef PB_DS_CLASS_T_DEC
443 #undef PB_DS_CLASS_C_DEC
444
445 #define PB_DS_CLASS_T_DEC
446 #define PB_DS_CLASS_C_DEC hash_prime_size_policy
447
448 /// A size policy whose sequence of sizes form a nearly-exponential
449 /// sequence of primes.
450 class hash_prime_size_policy
451 {
452 public:
453 /// Size type.
454 typedef std::size_t size_type;
455
456 /// Default constructor, or onstructor taking a start_size The
457 /// policy will use the sequence of sizes approximately
458 /// start_size, start_size* 2, start_size* 2^2, ...
459 hash_prime_size_policy(size_type start_size = 8);
460
461 inline void
462 swap(PB_DS_CLASS_C_DEC& other);
463
464 protected:
465 size_type
466 get_nearest_larger_size(size_type size) const;
467
468 size_type
469 get_nearest_smaller_size(size_type size) const;
470
471 private:
472 size_type m_start_size;
473 };
474
475 #include <ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp>
476
477 #undef PB_DS_CLASS_T_DEC
478 #undef PB_DS_CLASS_C_DEC
479
480 #define PB_DS_CLASS_T_DEC template<typename Size_Policy, typename Trigger_Policy, bool External_Size_Access, typename Size_Type>
481
482 #define PB_DS_CLASS_C_DEC hash_standard_resize_policy<Size_Policy, Trigger_Policy, External_Size_Access, Size_Type>
483
484 /// A resize policy which delegates operations to size and trigger policies.
485 template<typename Size_Policy = hash_exponential_size_policy<>,
486 typename Trigger_Policy = hash_load_check_resize_trigger<>,
487 bool External_Size_Access = false,
488 typename Size_Type = std::size_t>
489 class hash_standard_resize_policy
490 : public Size_Policy, public Trigger_Policy
491 {
492 public:
493 typedef Size_Type size_type;
494 typedef Trigger_Policy trigger_policy;
495 typedef Size_Policy size_policy;
496
497 enum
498 {
499 external_size_access = External_Size_Access
500 };
501
502 /// Default constructor.
503 hash_standard_resize_policy();
504
505 /// constructor taking some policies r_size_policy will be copied
506 /// by the Size_Policy object of this object.
507 hash_standard_resize_policy(const Size_Policy& r_size_policy);
508
509 /// constructor taking some policies. r_size_policy will be
510 /// copied by the Size_Policy object of this
511 /// object. r_trigger_policy will be copied by the Trigger_Policy
512 /// object of this object.
513 hash_standard_resize_policy(const Size_Policy& r_size_policy,
514 const Trigger_Policy& r_trigger_policy);
515
516 virtual
517 ~hash_standard_resize_policy();
518
519 inline void
520 swap(PB_DS_CLASS_C_DEC& other);
521
522 /// Access to the Size_Policy object used.
523 Size_Policy&
524 get_size_policy();
525
526 /// Const access to the Size_Policy object used.
527 const Size_Policy&
528 get_size_policy() const;
529
530 /// Access to the Trigger_Policy object used.
531 Trigger_Policy&
532 get_trigger_policy();
533
534 /// Access to the Trigger_Policy object used.
535 const Trigger_Policy&
536 get_trigger_policy() const;
537
538 /// Returns the actual size of the container.
539 inline size_type
540 get_actual_size() const;
541
542 /// Resizes the container to suggested_new_size, a suggested size
543 /// (the actual size will be determined by the Size_Policy
544 /// object).
545 void
546 resize(size_type suggested_new_size);
547
548 protected:
549 inline void
550 notify_insert_search_start();
551
552 inline void
553 notify_insert_search_collision();
554
555 inline void
556 notify_insert_search_end();
557
558 inline void
559 notify_find_search_start();
560
561 inline void
562 notify_find_search_collision();
563
564 inline void
565 notify_find_search_end();
566
567 inline void
568 notify_erase_search_start();
569
570 inline void
571 notify_erase_search_collision();
572
573 inline void
574 notify_erase_search_end();
575
576 inline void
577 notify_inserted(size_type num_e);
578
579 inline void
580 notify_erased(size_type num_e);
581
582 void
583 notify_cleared();
584
585 void
586 notify_resized(size_type new_size);
587
588 inline bool
589 is_resize_needed() const;
590
591 /// Queries what the new size should be, when the container is
592 /// resized naturally. The current __size of the container is
593 /// size, and the number of used entries within the container is
594 /// num_used_e.
595 size_type
596 get_new_size(size_type size, size_type num_used_e) const;
597
598 private:
599 /// Resizes to new_size.
600 virtual void
601 do_resize(size_type new_size);
602
603 typedef Trigger_Policy trigger_policy_base;
604
605 typedef Size_Policy size_policy_base;
606
607 size_type m_size;
608 };
609
610 #include <ext/pb_ds/detail/resize_policy/hash_standard_resize_policy_imp.hpp>
611
612 #undef PB_DS_CLASS_T_DEC
613 #undef PB_DS_CLASS_C_DEC
614
615 } // namespace __gnu_pbds
616
617 #endif