src/Collections/hashtable.h

   1 /*      Copyright (c) 2015 Regents of the University of California
   2  *
   3  *      Author: Brian Demsky <bdemsky@uci.edu>
   4  *
   5  *      This program is free software; you can redistribute it and/or
   6  *      modify it under the terms of the GNU General Public License
   7  *      version 2 as published by the Free Software Foundation.
   8  */
   9
  10 /** @file hashtable.h
  11  *  @brief Hashtable.  Standard chained bucket variety.
  12  */
  13
  14 #ifndef HASHTABLE_H__
  15 #define HASHTABLE_H__
  16
  17 #include <stdlib.h>
  18 #include <stdio.h>
  19 #include <string.h>
  20 #include "mymemory.h"
  21 #include "common.h"
  22
  23 /**
  24  * @brief Hashtable node
  25  *
  26  * @tparam _Key    Type name for the key
  27  * @tparam _Val    Type name for the values to be stored
  28  */
  29 template<typename _Key, typename _Val>
  30 struct Hashlistnode {
  31         _Key key;
  32         _Val val;
  33 };
  34
  35 template<typename _Key, int _Shift, typename _KeyInt>
  36 inline unsigned int defaultHashFunction(_Key hash) {
  37         return (unsigned int)(((_KeyInt)hash) >> _Shift);
  38 }
  39
  40 template<typename _Key>
  41 inline bool defaultEquals(_Key key1, _Key key2) {
  42         return key1 == key2;
  43 }
  44
  45 /**
  46  * @brief A simple, custom hash table
  47  *
  48  * By default it is snapshotting, but you can pass in your own allocation
  49  * functions. Note that this table does not support the value 0 (NULL) used as
  50  * a key and is designed primarily with pointer-based keys in mind. Other
  51  * primitive key types are supported only for non-zero values.
  52  *
  53  * @tparam _Key    Type name for the key
  54  * @tparam _Val    Type name for the values to be stored
  55  * @tparam _KeyInt Integer type that is at least as large as _Key. Used for key
  56  *                 manipulation and storage.
  57  * @tparam _Shift  Logical shift to apply to all keys. Default 0.
  58  */
  59 template<typename _Key, typename _Val, typename _KeyInt, int _Shift = 0, unsigned int (*hash_function)(_Key) = defaultHashFunction<_Key, _Shift, _KeyInt>, bool (*equals)(_Key, _Key) = defaultEquals<_Key> >
  60 class Hashtable {
  61 public:
  62         /**
  63          * @brief Hash table constructor
  64          * @param initialcapacity Sets the initial capacity of the hash table.
  65          * Default size 1024.
  66          * @param factor Sets the percentage full before the hashtable is
  67          * resized. Default ratio 0.5.
  68          */
  69         Hashtable(unsigned int initialcapacity = 1024, double factor = 0.5) {
  70                 // Allocate space for the hash table
  71                 table = (struct Hashlistnode<_Key, _Val> *)ourcalloc(initialcapacity, sizeof(struct Hashlistnode<_Key, _Val>));
  72                 zero = NULL;
  73                 loadfactor = factor;
  74                 capacity = initialcapacity;
  75                 capacitymask = initialcapacity - 1;
  76
  77                 threshold = (unsigned int)(initialcapacity * loadfactor);
  78                 size = 0;                                                       // Initial number of elements in the hash
  79         }
  80
  81         /** @brief Hash table destructor */
  82         ~Hashtable() {
  83                 ourfree(table);
  84                 if (zero)
  85                         ourfree(zero);
  86         }
  87
  88         /** Override: new operator */
  89         void *operator new(size_t size) {
  90                 return ourmalloc(size);
  91         }
  92
  93         /** Override: delete operator */
  94         void operator delete(void *p, size_t size) {
  95                 ourfree(p);
  96         }
  97
  98         /** Override: new[] operator */
  99         void *operator new[](size_t size) {
 100                 return ourmalloc(size);
 101         }
 102
 103         /** Override: delete[] operator */
 104         void operator delete[](void *p, size_t size) {
 105                 ourfree(p);
 106         }
 107
 108         /** @brief Reset the table to its initial state. */
 109         void reset() {
 110                 memset(table, 0, capacity * sizeof(struct Hashlistnode<_Key, _Val>));
 111                 if (zero) {
 112                         ourfree(zero);
 113                         zero = NULL;
 114                 }
 115                 size = 0;
 116         }
 117
 118         /** Doesn't work with zero value */
 119         _Val getRandomValue() {
 120                 while (true) {
 121                         unsigned int index = random() & capacitymask;
 122                         struct Hashlistnode<_Key, _Val> *bin = &table[index];
 123                         if (bin->key != NULL && bin->val != NULL) {
 124                                 return bin->val;
 125                         }
 126                 }
 127         }
 128
 129         void resetAndDeleteKeys() {
 130                 for (unsigned int i = 0; i < capacity; i++) {
 131                         struct Hashlistnode<_Key, _Val> *bin = &table[i];
 132                         if (bin->key != NULL) {
 133                                 delete bin->key;
 134                                 bin->key = NULL;
 135                                 if (bin->val != NULL) {
 136                                         bin->val = NULL;
 137                                 }
 138                         }
 139                 }
 140                 if (zero) {
 141                         ourfree(zero);
 142                         zero = NULL;
 143                 }
 144                 size = 0;
 145         }
 146
 147         void resetAndDeleteVals() {
 148                 for (unsigned int i = 0; i < capacity; i++) {
 149                         struct Hashlistnode<_Key, _Val> *bin = &table[i];
 150                         if (bin->key != NULL) {
 151                                 bin->key = NULL;
 152                                 if (bin->val != NULL) {
 153                                         delete bin->val;
 154                                         bin->val = NULL;
 155                                 }
 156                         }
 157                 }
 158                 if (zero) {
 159                         if (zero->val != NULL)
 160                                 delete zero->val;
 161                         ourfree(zero);
 162                         zero = NULL;
 163                 }
 164                 size = 0;
 165         }
 166
 167         void resetAndFreeVals() {
 168                 for (unsigned int i = 0; i < capacity; i++) {
 169                         struct Hashlistnode<_Key, _Val> *bin = &table[i];
 170                         if (bin->key != NULL) {
 171                                 bin->key = NULL;
 172                                 if (bin->val != NULL) {
 173                                         ourfree(bin->val);
 174                                         bin->val = NULL;
 175                                 }
 176                         }
 177                 }
 178                 if (zero) {
 179                         if (zero->val != NULL)
 180                                 ourfree(zero->val);
 181                         ourfree(zero);
 182                         zero = NULL;
 183                 }
 184                 size = 0;
 185         }
 186
 187         /**
 188          * @brief Put a key/value pair into the table
 189          * @param key The key for the new value; must not be 0 or NULL
 190          * @param val The value to store in the table
 191          */
 192         void put(_Key key, _Val val) {
 193                 /* Hashtable cannot handle 0 as a key */
 194                 if (!key) {
 195                         if (!zero) {
 196                                 zero = (struct Hashlistnode<_Key, _Val> *)ourmalloc(sizeof(struct Hashlistnode<_Key, _Val>));
 197                                 size++;
 198                         }
 199                         zero->key = key;
 200                         zero->val = val;
 201                         return;
 202                 }
 203
 204                 if (size > threshold)
 205                         resize(capacity << 1);
 206
 207                 struct Hashlistnode<_Key, _Val> *search;
 208
 209                 unsigned int index = hash_function(key);
 210                 do {
 211                         index &= capacitymask;
 212                         search = &table[index];
 213                         if (!search->key) {
 214                                 //key is null, probably done
 215                                 break;
 216                         }
 217                         if (equals(search->key, key)) {
 218                                 search->val = val;
 219                                 return;
 220                         }
 221                         index++;
 222                 } while (true);
 223
 224                 search->key = key;
 225                 search->val = val;
 226                 size++;
 227         }
 228
 229         /**
 230          * @brief Lookup the corresponding value for the given key
 231          * @param key The key for finding the value; must not be 0 or NULL
 232          * @return The value in the table, if the key is found; otherwise 0
 233          */
 234         _Val get(_Key key) const {
 235                 struct Hashlistnode<_Key, _Val> *search;
 236
 237                 /* Hashtable cannot handle 0 as a key */
 238                 if (!key) {
 239                         if (zero)
 240                                 return zero->val;
 241                         else
 242                                 return (_Val) 0;
 243                 }
 244
 245                 unsigned int oindex = hash_function(key) & capacitymask;
 246                 unsigned int index = oindex;
 247                 do {
 248                         search = &table[index];
 249                         if (!search->key) {
 250                                 if (!search->val)
 251                                         break;
 252                         } else
 253                         if (equals(search->key, key))
 254                                 return search->val;
 255                         index++;
 256                         index &= capacitymask;
 257                         if (index == oindex)
 258                                 break;
 259                 } while (true);
 260                 return (_Val)0;
 261         }
 262
 263         /**
 264          * @brief Remove the given key and return the corresponding value
 265          * @param key The key for finding the value; must not be 0 or NULL
 266          * @return The value in the table, if the key is found; otherwise 0
 267          */
 268         _Val remove(_Key key) {
 269                 struct Hashlistnode<_Key, _Val> *search;
 270
 271                 /* Hashtable cannot handle 0 as a key */
 272                 if (!key) {
 273                         if (!zero) {
 274                                 return (_Val)0;
 275                         } else {
 276                                 _Val v = zero->val;
 277                                 ourfree(zero);
 278                                 zero = NULL;
 279                                 size--;
 280                                 return v;
 281                         }
 282                 }
 283
 284
 285                 unsigned int index = hash_function(key);
 286                 do {
 287                         index &= capacitymask;
 288                         search = &table[index];
 289                         if (!search->key) {
 290                                 if (!search->val)
 291                                         break;
 292                         } else
 293                         if (equals(search->key, key)) {
 294                                 _Val v = search->val;
 295                                 //empty out this bin
 296                                 search->val = (_Val) 1;
 297                                 search->key = 0;
 298                                 size--;
 299                                 return v;
 300                         }
 301                         index++;
 302                 } while (true);
 303                 return (_Val)0;
 304         }
 305
 306         unsigned int getSize() const {
 307                 return size;
 308         }
 309
 310
 311         /**
 312          * @brief Check whether the table contains a value for the given key
 313          * @param key The key for finding the value; must not be 0 or NULL
 314          * @return True, if the key is found; false otherwise
 315          */
 316         bool contains(_Key key) const {
 317                 struct Hashlistnode<_Key, _Val> *search;
 318
 319                 /* Hashtable cannot handle 0 as a key */
 320                 if (!key) {
 321                         return zero != NULL;
 322                 }
 323
 324                 unsigned int index = hash_function(key);
 325                 do {
 326                         index &= capacitymask;
 327                         search = &table[index];
 328                         if (!search->key) {
 329                                 if (!search->val)
 330                                         break;
 331                         } else
 332                         if (equals(search->key, key))
 333                                 return true;
 334                         index++;
 335                 } while (true);
 336                 return false;
 337         }
 338
 339         /**
 340          * @brief Resize the table
 341          * @param newsize The new size of the table
 342          */
 343         void resize(unsigned int newsize) {
 344                 struct Hashlistnode<_Key, _Val> *oldtable = table;
 345                 struct Hashlistnode<_Key, _Val> *newtable;
 346                 unsigned int oldcapacity = capacity;
 347
 348                 if ((newtable = (struct Hashlistnode<_Key, _Val> *)ourcalloc(newsize, sizeof(struct Hashlistnode<_Key, _Val>))) == NULL) {
 349                         model_print("calloc error %s %d\n", __FILE__, __LINE__);
 350                         exit(EXIT_FAILURE);
 351                 }
 352
 353                 table = newtable;                                                                                       // Update the global hashtable upon resize()
 354                 capacity = newsize;
 355                 capacitymask = newsize - 1;
 356
 357                 threshold = (unsigned int)(newsize * loadfactor);
 358
 359                 struct Hashlistnode<_Key, _Val> *bin = &oldtable[0];
 360                 struct Hashlistnode<_Key, _Val> *lastbin = &oldtable[oldcapacity];
 361                 for (; bin < lastbin; bin++) {
 362                         _Key key = bin->key;
 363
 364                         struct Hashlistnode<_Key, _Val> *search;
 365                         if (!key)
 366                                 continue;
 367
 368                         unsigned int index = hash_function(key);
 369                         do {
 370                                 index &= capacitymask;
 371                                 search = &table[index];
 372                                 index++;
 373                         } while (search->key);
 374
 375                         search->key = key;
 376                         search->val = bin->val;
 377                 }
 378
 379                 ourfree(oldtable);                                                                                              // Free the memory of the old hash table
 380         }
 381         double getLoadFactor() {return loadfactor;}
 382         unsigned int getCapacity() {return capacity;}
 383         struct Hashlistnode<_Key, _Val> *table;
 384         struct Hashlistnode<_Key, _Val> *zero;
 385         unsigned int capacity;
 386         unsigned int size;
 387 private:
 388         unsigned int capacitymask;
 389         unsigned int threshold;
 390         double loadfactor;
 391 };
 392
 393 #endif/* __HASHTABLE_H__ */