nsz Git - cparser/blob - adt/hashset.c.inl

   1 /*
   2  * Copyright (C) 1995-2012 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief   Generic hashset implementation
  23  * @author  Matthias Braun, inspiration from densehash from google sparsehash
  24  *          package
  25  * @date    17.03.2007
  26  *
  27  *
  28  * You have to specialize this file by defining:
  29  *
  30  * <ul>
  31  *  <li><b>HashSet</b>         The name of the hashset type</li>
  32  *  <li><b>HashSetIterator</b> The name of the hashset iterator type</li>
  33  *  <li><b>ValueType</b>       The type of the stored data values</li>
  34  *  <li><b>NullValue</b>       A special value representing no values</li>
  35  *  <li><b>DeletedValue</b>    A special value representing deleted entries</li>
  36  *  <li><b>Hash(hashset,key)</b> calculates the hash value for a given key</li>
  37  * </ul>
  38  *
  39  * Note that by default it is assumed that the data values themselves are used
  40  * as keys. However you can change that with additional defines:
  41  *
  42  * <ul>
  43  *  <li><b>KeyType</b>         The type of the keys identifying data values.
  44  *                             Defining this implies, that a data value contains
  45  *                             more than just the key.</li>
  46  *  <li><b>GetKey(value)</b>   Extracts the key from a data value</li>
  47  *  <li><b>KeysEqual(hashset,key1,key2)</b>  Tests wether 2 keys are equal</li>
  48  *  <li><b>DO_REHASH</b>       Instead of storing the hash-values, recalculate
  49  *                             them on demand from the datavalues. (useful if
  50  *                             calculating the hash-values takes less time than
  51  *                             a memory access)</li>
  52  * </ul>
  53  *
  54  * You can further fine tune your hashset by defining the following:
  55  *
  56  * <ul>
  57  *  <li><b>JUMP(num_probes)</b> The probing method</li>
  58  *  <li><b>Alloc(count)</b>     Allocates count hashset entries (NOT bytes)</li>
  59  *  <li><b>Free(ptr)</b>        Frees a block of memory allocated by Alloc</li>
  60  *  <li><b>SetRangeEmpty(ptr,count)</b> Efficiently sets a range of elements to
  61  *                                      the Null value</li>
  62  *  <li><b>ADDITIONAL_DATA<b>   Additional fields appended to the hashset struct</li>
  63  * </ul>
  64  */
  65 #ifdef HashSet
  66
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <assert.h>
  70
  71 #include "bitfiddle.h"
  72 #include "util.h"
  73
  74 /* quadratic probing */
  75 #ifndef JUMP
  76 #define JUMP(num_probes)      (num_probes)
  77 #endif /* JUMP */
  78
  79 #ifndef Hash
  80 #define ID_HASH
  81 #define Hash(self,key)        ((unsigned)(((char *)key) - (char *)0))
  82 #endif /* Hash */
  83
  84 #ifdef DO_REHASH
  85 #define HashSetEntry                   ValueType
  86 #define EntrySetHash(entry,new_hash)   ((void)0)
  87 #define EntryGetHash(self,entry)       Hash(self, GetKey(entry))
  88 #define EntryGetValue(entry)           (entry)
  89 #else /* ! DO_REHASH */
  90 #define EntryGetHash(self,entry)       (entry).hash
  91 #define EntrySetHash(entry,new_hash)   (entry).hash = (new_hash)
  92 #define EntryGetValue(entry)           (entry).data
  93 #endif /* DO_REHASH */
  94
  95 #ifndef Alloc
  96 #include "xmalloc.h"
  97 #define Alloc(size) XMALLOCN(HashSetEntry, (size))
  98 #define Free(ptr)      free(ptr)
  99 #endif /* Alloc */
 100
 101 #ifdef ID_HASH
 102 #define FindReturnValue                 bool
 103 #define GetFindReturnValue(entry,found) (found)
 104 #define NullReturnValue                 false
 105 #define InsertReturnValue(findreturn)   !(findreturn)
 106 #else /* ! ID_HASH */
 107 #ifdef SCALAR_RETURN
 108 #define FindReturnValue                 ValueType
 109 #define GetFindReturnValue(entry,found) EntryGetValue(entry)
 110 #define NullReturnValue                 NullValue
 111 #else
 112 #define FindReturnValue                 ValueType*
 113 #define GetFindReturnValue(entry,found) & EntryGetValue(entry)
 114 #define NullReturnValue                 & NullValue
 115 #endif
 116 #endif /* ID_HASH */
 117
 118 #ifndef InsertReturnValue
 119 #define InsertReturnValue(findreturn)   findreturn
 120 #endif
 121
 122 #ifndef KeyType
 123 #define KeyType                  ValueType
 124 #define GetKey(value)            (value)
 125 #define InitData(self,value,key) (value) = (key)
 126 #endif /* KeyType */
 127
 128 #ifndef ConstKeyType
 129 #define ConstKeyType             const KeyType
 130 #endif /* ConstKeyType */
 131
 132 #ifndef EntrySetEmpty
 133 #define EntrySetEmpty(entry)    EntryGetValue(entry) = NullValue
 134 #endif /* EntrySetEmpty */
 135 #ifndef EntrySetDeleted
 136 #define EntrySetDeleted(entry)  EntryGetValue(entry) = DeletedValue
 137 #endif /* EntrySetDeleted */
 138 #ifndef EntryIsEmpty
 139 #define EntryIsEmpty(entry)     (EntryGetValue(entry) == NullValue)
 140 #endif /* EntryIsEmpty */
 141 #ifndef EntryIsDeleted
 142 #define EntryIsDeleted(entry)   (EntryGetValue(entry) == DeletedValue)
 143 #endif /* EntryIsDeleted */
 144 #ifndef SetRangeEmpty
 145 #define SetRangeEmpty(ptr,size)                \
 146 {                                              \
 147         size_t _i;                                 \
 148         size_t _size = (size);                     \
 149         HashSetEntry *entries = (ptr);             \
 150         for (_i = 0; _i < _size; ++_i) {            \
 151                 HashSetEntry *entry = & entries[_i];   \
 152                 EntrySetEmpty(*entry);                 \
 153         }                                          \
 154 }
 155 #endif /* SetRangeEmpty */
 156
 157 #ifndef HT_OCCUPANCY_FLT
 158 /** how full before we double size */
 159 #define HT_OCCUPANCY_FLT(x) ((x)/2)
 160 #endif /* HT_OCCUPANCY_FLT */
 161 #ifndef HT_1_DIV_OCCUPANCY_FLT
 162 #define HT_1_DIV_OCCUPANCY_FLT 2
 163 #endif
 164
 165 #ifndef HT_EMPTY_FLT
 166 /** how empty before we half size */
 167 #define HT_EMPTY_FLT(x)     ((x)/5)
 168 #endif /* HT_EMPTY_FLT */
 169
 170 #ifndef HT_MIN_BUCKETS
 171 /** default smallest bucket size */
 172 #define HT_MIN_BUCKETS    32
 173 #endif /* HT_MIN_BUCKETS */
 174
 175 #define ILLEGAL_POS       ((size_t)-1)
 176
 177 #ifdef hashset_size
 178 /**
 179  * Returns the number of elements in the hashset
 180  */
 181 size_t hashset_size(const HashSet *self)
 182 {
 183         return self->num_elements - self->num_deleted;
 184 }
 185 #else
 186 static inline size_t hashset_size(const HashSet *self)
 187 {
 188         return self->num_elements - self->num_deleted;
 189 }
 190 #endif
 191
 192 /**
 193  * Inserts an element into a hashset without growing the set (you have to make
 194  * sure there's enough room for that.
 195  * @returns  previous value if found, NullValue otherwise
 196  * @note also see comments for hashset_insert()
 197  * @internal
 198  */
 199 static inline FindReturnValue insert_nogrow(HashSet *self, KeyType key)
 200 {
 201         size_t   num_probes  = 0;
 202         size_t   num_buckets = self->num_buckets;
 203         size_t   hashmask    = num_buckets - 1;
 204         unsigned hash        = Hash(self, key);
 205         size_t   bucknum     = hash & hashmask;
 206         size_t   insert_pos  = ILLEGAL_POS;
 207
 208         assert((num_buckets & (num_buckets - 1)) == 0);
 209
 210         for (;;) {
 211                 HashSetEntry *entry = & self->entries[bucknum];
 212
 213                 if (EntryIsEmpty(*entry)) {
 214                         size_t p;
 215                         HashSetEntry *nentry;
 216
 217                         if (insert_pos != ILLEGAL_POS) {
 218                                 p = insert_pos;
 219                         } else {
 220                                 p = bucknum;
 221                         }
 222
 223                         nentry = &self->entries[p];
 224                         InitData(self, EntryGetValue(*nentry), key);
 225                         EntrySetHash(*nentry, hash);
 226                         self->num_elements++;
 227                         return GetFindReturnValue(*nentry, false);
 228                 }
 229                 if (EntryIsDeleted(*entry)) {
 230                         if (insert_pos == ILLEGAL_POS)
 231                                 insert_pos = bucknum;
 232                 } else if (EntryGetHash(self, *entry) == hash) {
 233                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 234                                 // Value already in the set, return it
 235                                 return GetFindReturnValue(*entry, true);
 236                         }
 237                 }
 238
 239                 ++num_probes;
 240                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 241                 assert(num_probes < num_buckets);
 242         }
 243 }
 244
 245 /**
 246  * calculate shrink and enlarge limits
 247  * @internal
 248  */
 249 static inline void reset_thresholds(HashSet *self)
 250 {
 251         self->enlarge_threshold = (size_t) HT_OCCUPANCY_FLT(self->num_buckets);
 252         self->shrink_threshold  = (size_t) HT_EMPTY_FLT(self->num_buckets);
 253         self->consider_shrink   = 0;
 254 }
 255
 256 #ifndef HAVE_OWN_RESIZE
 257 /**
 258  * Inserts an element into a hashset under the assumption that the hashset
 259  * contains no deleted entries and the element doesn't exist in the hashset yet.
 260  * @internal
 261  */
 262 static void insert_new(HashSet *self, unsigned hash, ValueType value)
 263 {
 264         size_t num_probes  = 0;
 265         size_t num_buckets = self->num_buckets;
 266         size_t hashmask    = num_buckets - 1;
 267         size_t bucknum     = hash & hashmask;
 268         size_t insert_pos  = ILLEGAL_POS;
 269
 270         //assert(value != NullValue);
 271
 272         for (;;) {
 273                 HashSetEntry *entry = & self->entries[bucknum];
 274
 275                 if (EntryIsEmpty(*entry)) {
 276                         size_t        p;
 277                         HashSetEntry *nentry;
 278
 279                         if (insert_pos != ILLEGAL_POS) {
 280                                 p = insert_pos;
 281                         } else {
 282                                 p = bucknum;
 283                         }
 284                         nentry = &self->entries[p];
 285
 286                         EntryGetValue(*nentry) = value;
 287                         EntrySetHash(*nentry, hash);
 288                         self->num_elements++;
 289                         return;
 290                 }
 291                 assert(!EntryIsDeleted(*entry));
 292
 293                 ++num_probes;
 294                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 295                 assert(num_probes < num_buckets);
 296         }
 297 }
 298
 299 /**
 300  * Resize the hashset
 301  * @internal
 302  */
 303 static inline void resize(HashSet *self, size_t new_size)
 304 {
 305         size_t num_buckets = self->num_buckets;
 306         size_t i;
 307         HashSetEntry *old_entries = self->entries;
 308         HashSetEntry *new_entries;
 309
 310         /* allocate a new array with double size */
 311         new_entries = Alloc(new_size);
 312         SetRangeEmpty(new_entries, new_size);
 313
 314         /* use the new array */
 315         self->entries      = new_entries;
 316         self->num_buckets  = new_size;
 317         self->num_elements = 0;
 318         self->num_deleted  = 0;
 319 #ifndef NDEBUG
 320         self->entries_version++;
 321 #endif
 322         reset_thresholds(self);
 323
 324         /* reinsert all elements */
 325         for (i = 0; i < num_buckets; ++i) {
 326                 HashSetEntry *entry = & old_entries[i];
 327                 if (EntryIsEmpty(*entry) || EntryIsDeleted(*entry))
 328                         continue;
 329
 330                 insert_new(self, EntryGetHash(self, *entry), EntryGetValue(*entry));
 331         }
 332
 333         /* now we can free the old array */
 334         Free(old_entries);
 335 }
 336 #else
 337
 338 /* resize must be defined outside */
 339 static inline void resize(HashSet *self, size_t new_size);
 340
 341 #endif
 342
 343 /**
 344  * grow the hashset if adding 1 more elements would make it too crowded
 345  * @internal
 346  */
 347 static inline void maybe_grow(HashSet *self)
 348 {
 349         size_t resize_to;
 350
 351         if (LIKELY(self->num_elements + 1 <= self->enlarge_threshold))
 352                 return;
 353
 354         /* double table size */
 355         resize_to = self->num_buckets * 2;
 356         resize(self, resize_to);
 357 }
 358
 359 /**
 360  * shrink the hashset if it is only sparsely filled
 361  * @internal
 362  */
 363 static inline void maybe_shrink(HashSet *self)
 364 {
 365         size_t size;
 366         size_t resize_to;
 367
 368         if (!self->consider_shrink)
 369                 return;
 370
 371         self->consider_shrink = 0;
 372         size                  = hashset_size(self);
 373         if (size <= HT_MIN_BUCKETS)
 374                 return;
 375
 376         if (LIKELY(size > self->shrink_threshold))
 377                 return;
 378
 379         resize_to = ceil_po2(size);
 380
 381         if (resize_to < 4)
 382                 resize_to = 4;
 383
 384         resize(self, resize_to);
 385 }
 386
 387 #ifdef hashset_insert
 388 /**
 389  * Insert an element into the hashset. If no element with the given key exists yet,
 390  * then a new one is created and initialized with the InitData function.
 391  * Otherwise the existing element is returned (for hashs where key is equal to
 392  * value, nothing is returned.)
 393  *
 394  * @param self   the hashset
 395  * @param key    the key that identifies the data
 396  * @returns      the existing or newly created data element (or nothing in case of hashs where keys are the while value)
 397  */
 398 FindReturnValue hashset_insert(HashSet *self, KeyType key)
 399 {
 400 #ifndef NDEBUG
 401         self->entries_version++;
 402 #endif
 403
 404         maybe_shrink(self);
 405         maybe_grow(self);
 406         return InsertReturnValue(insert_nogrow(self, key));
 407 }
 408 #endif
 409
 410 #ifdef hashset_find
 411 /**
 412  * Searches for an element with key @p key.
 413  *
 414  * @param self      the hashset
 415  * @param key       the key to search for
 416  * @returns         the found value or NullValue if nothing was found
 417  */
 418 FindReturnValue hashset_find(const HashSet *self, ConstKeyType key)
 419 {
 420         size_t   num_probes  = 0;
 421         size_t   num_buckets = self->num_buckets;
 422         size_t   hashmask    = num_buckets - 1;
 423         unsigned hash        = Hash(self, key);
 424         size_t   bucknum     = hash & hashmask;
 425
 426         for (;;) {
 427                 HashSetEntry *entry = & self->entries[bucknum];
 428
 429                 if (EntryIsEmpty(*entry)) {
 430                         return NullReturnValue;
 431                 }
 432                 if (EntryIsDeleted(*entry)) {
 433                         // value is deleted
 434                 } else if (EntryGetHash(self, *entry) == hash) {
 435                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 436                                 // found the value
 437                                 return GetFindReturnValue(*entry, true);
 438                         }
 439                 }
 440
 441                 ++num_probes;
 442                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 443                 assert(num_probes < num_buckets);
 444         }
 445 }
 446 #endif
 447
 448 #ifdef hashset_remove
 449 /**
 450  * Removes an element from a hashset. Does nothing if the set doesn't contain
 451  * the element.
 452  *
 453  * @param self    the hashset
 454  * @param key     key that identifies the data to remove
 455  */
 456 void hashset_remove(HashSet *self, ConstKeyType key)
 457 {
 458         size_t   num_probes  = 0;
 459         size_t   num_buckets = self->num_buckets;
 460         size_t   hashmask    = num_buckets - 1;
 461         unsigned hash        = Hash(self, key);
 462         size_t   bucknum     = hash & hashmask;
 463
 464 #ifndef NDEBUG
 465         self->entries_version++;
 466 #endif
 467
 468         for (;;) {
 469                 HashSetEntry *entry = & self->entries[bucknum];
 470
 471                 if (EntryIsEmpty(*entry)) {
 472                         return;
 473                 }
 474                 if (EntryIsDeleted(*entry)) {
 475                         // entry is deleted
 476                 } else if (EntryGetHash(self, *entry) == hash) {
 477                         if (KeysEqual(self, GetKey(EntryGetValue(*entry)), key)) {
 478                                 EntrySetDeleted(*entry);
 479                                 self->num_deleted++;
 480                                 self->consider_shrink = 1;
 481                                 return;
 482                         }
 483                 }
 484
 485                 ++num_probes;
 486                 bucknum = (bucknum + JUMP(num_probes)) & hashmask;
 487                 assert(num_probes < num_buckets);
 488         }
 489 }
 490 #endif
 491
 492 /**
 493  * Initializes hashset with a specific size
 494  * @internal
 495  */
 496 static inline void init_size(HashSet *self, size_t initial_size)
 497 {
 498         if (initial_size < 4)
 499                 initial_size = 4;
 500
 501         self->entries         = Alloc(initial_size);
 502         SetRangeEmpty(self->entries, initial_size);
 503         self->num_buckets     = initial_size;
 504         self->consider_shrink = 0;
 505         self->num_elements    = 0;
 506         self->num_deleted     = 0;
 507 #ifndef NDEBUG
 508         self->entries_version = 0;
 509 #endif
 510 #ifdef ADDITIONAL_INIT
 511         ADDITIONAL_INIT
 512 #endif
 513
 514         reset_thresholds(self);
 515 }
 516
 517 #ifdef hashset_init
 518 /**
 519  * Initializes a hashset with the default size. The memory for the set has to
 520  * already allocated.
 521  */
 522 void hashset_init(HashSet *self)
 523 {
 524         init_size(self, HT_MIN_BUCKETS);
 525 }
 526 #endif
 527
 528 #ifdef hashset_destroy
 529 /**
 530  * Destroys a hashset, freeing all used memory (except the memory for the
 531  * HashSet struct itself).
 532  */
 533 void hashset_destroy(HashSet *self)
 534 {
 535 #ifdef ADDITIONAL_TERM
 536         ADDITIONAL_TERM
 537 #endif
 538         Free(self->entries);
 539 #ifndef NDEBUG
 540         self->entries = NULL;
 541 #endif
 542 }
 543 #endif
 544
 545 #ifdef hashset_init_size
 546 /**
 547  * Initializes a hashset expecting expected_element size.
 548  */
 549 void hashset_init_size(HashSet *self, size_t expected_elements)
 550 {
 551         size_t needed_size;
 552         size_t po2size;
 553
 554         if (expected_elements >= UINT_MAX/2) {
 555                 abort();
 556         }
 557
 558         needed_size = expected_elements * HT_1_DIV_OCCUPANCY_FLT;
 559         po2size     = ceil_po2(needed_size);
 560         init_size(self, po2size);
 561 }
 562 #endif
 563
 564 #ifdef hashset_iterator_init
 565 /**
 566  * Initializes a hashset iterator. The memory for the allocator has to be
 567  * already allocated.
 568  * @note it is not allowed to remove or insert elements while iterating
 569  */
 570 void hashset_iterator_init(HashSetIterator *self, const HashSet *hashset)
 571 {
 572         self->current_bucket = hashset->entries - 1;
 573         self->end            = hashset->entries + hashset->num_buckets;
 574 #ifndef NDEBUG
 575         self->set             = hashset;
 576         self->entries_version = hashset->entries_version;
 577 #endif
 578 }
 579 #endif
 580
 581 #ifdef hashset_iterator_next
 582 /**
 583  * Returns the next value in the iterator or NULL if no value is left
 584  * in the hashset.
 585  * @note it is not allowed to remove or insert elements while iterating
 586  */
 587 ValueType hashset_iterator_next(HashSetIterator *self)
 588 {
 589         HashSetEntry *current_bucket = self->current_bucket;
 590         HashSetEntry *end            = self->end;
 591
 592         /* using hashset_insert or hashset_remove is not allowed while iterating */
 593         assert(self->entries_version == self->set->entries_version);
 594
 595         do {
 596                 current_bucket++;
 597                 if (current_bucket >= end)
 598                         return NullValue;
 599         } while (EntryIsEmpty(*current_bucket) || EntryIsDeleted(*current_bucket));
 600
 601         self->current_bucket = current_bucket;
 602         return EntryGetValue(*current_bucket);
 603 }
 604 #endif
 605
 606 #ifdef hashset_remove_iterator
 607 /**
 608  * Removes the element the iterator points to. Removing an element a second time
 609  * has no result.
 610  */
 611 void hashset_remove_iterator(HashSet *self, const HashSetIterator *iter)
 612 {
 613         HashSetEntry *entry = iter->current_bucket;
 614
 615         /* iterator_next needs to have been called at least once */
 616         assert(entry >= self->entries);
 617         /* needs to be on a valid element */
 618         assert(entry < self->entries + self->num_buckets);
 619
 620         if (EntryIsDeleted(*entry))
 621                 return;
 622
 623         EntrySetDeleted(*entry);
 624         self->num_deleted++;
 625         self->consider_shrink = 1;
 626 }
 627 #endif
 628
 629 #endif