lib/gl_omap.h

   1 /* Abstract ordered map data type.
   2    Copyright (C) 2006-2007, 2009-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2018.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _GL_OMAP_H
  19 #define _GL_OMAP_H
  20
  21 #include <stdbool.h>
  22 #include <stddef.h>
  23
  24 #ifndef _GL_INLINE_HEADER_BEGIN
  25  #error "Please include config.h first."
  26 #endif
  27 _GL_INLINE_HEADER_BEGIN
  28 #ifndef GL_OMAP_INLINE
  29 # define GL_OMAP_INLINE _GL_INLINE
  30 #endif
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36
  37 /* gl_omap is an abstract ordered map data type.  It can contain any number
  38    of (key, value) pairs, where
  39      - keys and values are objects ('void *' or 'const void *' pointers),
  40      - The (key, value) pairs are ordered by the key, in the order of a given
  41        comparator function.
  42      - There are no (key, value1) and (key, value2) pairs with the same key
  43        (in the sense of the comparator function).
  44
  45    There are several implementations of this ordered map datatype, optimized
  46    for different operations or for memory.  You can start using the simplest
  47    ordered map implementation, GL_ARRAY_OMAP, and switch to a different
  48    implementation later, when you realize which operations are performed
  49    the most frequently.  The API of the different implementations is exactly
  50    the same; when switching to a different implementation, you only have to
  51    change the gl_omap_create call.
  52
  53    The implementations are:
  54      GL_ARRAY_OMAP        a growable array
  55      GL_AVLTREE_OMAP      a binary tree (AVL tree)
  56      GL_RBTREE_OMAP       a binary tree (red-black tree)
  57
  58    The memory consumption is asymptotically the same: O(1) for every pair
  59    in the map.  When looking more closely at the average memory consumed
  60    for an pair, GL_ARRAY_OMAP is the most compact representation, and
  61    GL_AVLTREE_OMAP, GL_RBTREE_OMAP need more memory.
  62
  63    The guaranteed average performance of the operations is, for a map of
  64    n pairs:
  65
  66    Operation                  ARRAY     TREE
  67
  68    gl_omap_size                O(1)     O(1)
  69    gl_omap_get               O(log n) O(log n)
  70    gl_omap_put                 O(n)   O(log n)
  71    gl_omap_remove              O(n)   O(log n)
  72    gl_omap_search            O(log n) O(log n)
  73    gl_omap_search_atleast    O(log n) O(log n)
  74    gl_omap_iterator            O(1)   O(log n)
  75    gl_omap_iterator_next       O(1)   O(log n)
  76  */
  77
  78 /* -------------------------- gl_omap_t Data Type -------------------------- */
  79
  80 /* Type of function used to compare two keys.  Same as for qsort().
  81    NULL denotes pointer comparison.  */
  82 typedef int (*gl_mapkey_compar_fn) (const void *key1, const void *key2);
  83
  84 #ifndef _GL_MAP_DISPOSE_FNS_DEFINED
  85
  86 /* Type of function used to dispose a key once a (key, value) pair is removed
  87    from a map.  NULL denotes a no-op.  */
  88 typedef void (*gl_mapkey_dispose_fn) (const void *key);
  89
  90 /* Type of function used to dispose a value once a (key, value) pair is removed
  91    from a map.  NULL denotes a no-op.  */
  92 typedef void (*gl_mapvalue_dispose_fn) (const void *value);
  93
  94 # define _GL_MAP_DISPOSE_FNS_DEFINED 1
  95 #endif
  96
  97 /* Type of function used to compare a key with a threshold.
  98    Returns true if the key is greater or equal than the threshold.  */
  99 typedef bool (*gl_mapkey_threshold_fn) (const void *key, const void *threshold);
 100
 101 struct gl_omap_impl;
 102 /* Type representing an entire ordered map.  */
 103 typedef struct gl_omap_impl * gl_omap_t;
 104
 105 struct gl_omap_implementation;
 106 /* Type representing a ordered map datatype implementation.  */
 107 typedef const struct gl_omap_implementation * gl_omap_implementation_t;
 108
 109 #if 0 /* Unless otherwise specified, these are defined inline below.  */
 110
 111 /* Creates an empty map.
 112    IMPLEMENTATION is one of GL_ARRAY_OMAP, GL_AVLTREE_OMAP, GL_RBTREE_OMAP.
 113    COMPAR_FN is a key comparison function or NULL.
 114    KDISPOSE_FN is a key disposal function or NULL.
 115    VDISPOSE_FN is a value disposal function or NULL.  */
 116 /* declared in gl_xomap.h */
 117 extern gl_omap_t gl_omap_create_empty (gl_omap_implementation_t implementation,
 118                                        gl_mapkey_compar_fn compar_fn,
 119                                        gl_mapkey_dispose_fn kdispose_fn,
 120                                        gl_mapvalue_dispose_fn vdispose_fn);
 121 /* Likewise.  Returns NULL upon out-of-memory.  */
 122 extern gl_omap_t gl_omap_nx_create_empty (gl_omap_implementation_t implementation,
 123                                           gl_mapkey_compar_fn compar_fn,
 124                                           gl_mapkey_dispose_fn kdispose_fn,
 125                                           gl_mapvalue_dispose_fn vdispose_fn);
 126
 127 /* Returns the current number of pairs in an ordered map.  */
 128 extern size_t gl_omap_size (gl_omap_t map);
 129
 130 /* Searches whether a pair with the given key is already in the ordered map.
 131    Returns the value if found, or NULL if not present in the map.  */
 132 extern const void * gl_omap_get (gl_omap_t map, const void *key);
 133
 134 /* Searches whether a pair with the given key is already in the ordered map.
 135    Returns true and sets *VALUEP to the value if found.
 136    Returns false if not present in the map.  */
 137 extern bool gl_omap_search (gl_omap_t map, const void *key,
 138                             const void **valuep);
 139
 140 /* Searches the pair with the least key in the ordered map that compares
 141    greater or equal to the given THRESHOLD.  The representation of the
 142    THRESHOLD is defined by the THRESHOLD_FN.
 143    Returns true and stores the found pair in *KEYP and *VALUEP if found.
 144    Otherwise returns false.  */
 145 extern bool gl_omap_search_atleast (gl_omap_t map,
 146                                     gl_mapkey_threshold_fn threshold_fn,
 147                                     const void *threshold,
 148                                     const void **keyp, const void **valuep);
 149
 150 /* Adds a pair to an ordered map.
 151    Returns true if a pair with the given key was not already in the map and so
 152    this pair was added.
 153    Returns false if a pair with the given key was already in the map and only
 154    its value was replaced.  */
 155 /* declared in gl_xomap.h */
 156 extern bool gl_omap_put (gl_omap_t map, const void *key, const void *value);
 157 /* Likewise.  Returns -1 upon out-of-memory.  */
 158 extern int gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
 159   _GL_ATTRIBUTE_NODISCARD;
 160
 161 /* Adds a pair to an ordered map and retrieves the previous value.
 162    Returns true if a pair with the given key was not already in the map and so
 163    this pair was added.
 164    Returns false and sets *OLDVALUEP to the previous value, if a pair with the
 165    given key was already in the map and only its value was replaced.  */
 166 /* declared in gl_xomap.h */
 167 extern bool gl_omap_getput (gl_omap_t map, const void *key, const void *value,
 168                             const void **oldvaluep);
 169 /* Likewise.  Returns -1 upon out-of-memory.  */
 170 extern int gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
 171                               const void **oldvaluep)
 172   _GL_ATTRIBUTE_NODISCARD;
 173
 174 /* Removes a pair from an ordered map.
 175    Returns true if the key was found and its pair removed.
 176    Returns false otherwise.  */
 177 extern bool gl_omap_remove (gl_omap_t map, const void *key);
 178
 179 /* Removes a pair from an ordered map and retrieves the previous value.
 180    Returns true and sets *OLDVALUEP to the previous value, if the key was found
 181    and its pair removed.
 182    Returns false otherwise.  */
 183 extern bool gl_omap_getremove (gl_omap_t map, const void *key,
 184                                const void **oldvaluep);
 185
 186 /* Frees an entire ordered map.
 187    (But this call does not free the keys and values of the pairs in the map.
 188    It only invokes the KDISPOSE_FN on each key and the VDISPOSE_FN on each value
 189    of the pairs in the map.)  */
 190 extern void gl_omap_free (gl_omap_t map);
 191
 192 #endif /* End of inline and gl_xomap.h-defined functions.  */
 193
 194 /* ---------------------- gl_omap_iterator_t Data Type ---------------------- */
 195
 196 /* Functions for iterating through an ordered map.  */
 197
 198 /* Type of an iterator that traverses an ordered map.
 199    This is a fixed-size struct, so that creation of an iterator doesn't need
 200    memory allocation on the heap.  */
 201 typedef struct
 202 {
 203   /* For fast dispatch of gl_omap_iterator_next.  */
 204   const struct gl_omap_implementation *vtable;
 205   /* For detecting whether the last returned pair was removed.  */
 206   gl_omap_t map;
 207   size_t count;
 208   /* Other, implementation-private fields.  */
 209   void *p; void *q;
 210   size_t i; size_t j;
 211 } gl_omap_iterator_t;
 212
 213 #if 0 /* These are defined inline below.  */
 214
 215 /* Creates an iterator traversing an ordered map.
 216    The map's contents must not be modified while the iterator is in use,
 217    except for modifying the value of the last returned key or removing the
 218    last returned pair.  */
 219 extern gl_omap_iterator_t gl_omap_iterator (gl_omap_t map);
 220
 221 /* If there is a next pair, stores the next pair in *KEYP and *VALUEP, advances
 222    the iterator, and returns true.  Otherwise, returns false.  */
 223 extern bool gl_omap_iterator_next (gl_omap_iterator_t *iterator,
 224                                    const void **keyp, const void **valuep);
 225
 226 /* Frees an iterator.  */
 227 extern void gl_omap_iterator_free (gl_omap_iterator_t *iterator);
 228
 229 #endif /* End of inline functions.  */
 230
 231 /* ------------------------- Implementation Details ------------------------- */
 232
 233 struct gl_omap_implementation
 234 {
 235   /* gl_omap_t functions.  */
 236   gl_omap_t (*nx_create_empty) (gl_omap_implementation_t implementation,
 237                                 gl_mapkey_compar_fn compar_fn,
 238                                 gl_mapkey_dispose_fn kdispose_fn,
 239                                 gl_mapvalue_dispose_fn vdispose_fn);
 240   size_t (*size) (gl_omap_t map);
 241   bool (*search) (gl_omap_t map, const void *key, const void **valuep);
 242   bool (*search_atleast) (gl_omap_t map,
 243                           gl_mapkey_threshold_fn threshold_fn,
 244                           const void *threshold,
 245                           const void **keyp, const void **valuep);
 246   int (*nx_getput) (gl_omap_t map, const void *key, const void *value,
 247                     const void **oldvaluep);
 248   bool (*getremove) (gl_omap_t map, const void *key, const void **oldvaluep);
 249   void (*omap_free) (gl_omap_t map);
 250   /* gl_omap_iterator_t functions.  */
 251   gl_omap_iterator_t (*iterator) (gl_omap_t map);
 252   bool (*iterator_next) (gl_omap_iterator_t *iterator,
 253                          const void **keyp, const void **valuep);
 254   void (*iterator_free) (gl_omap_iterator_t *iterator);
 255 };
 256
 257 struct gl_omap_impl_base
 258 {
 259   const struct gl_omap_implementation *vtable;
 260   gl_mapkey_compar_fn compar_fn;
 261   gl_mapkey_dispose_fn kdispose_fn;
 262   gl_mapvalue_dispose_fn vdispose_fn;
 263 };
 264
 265 /* Define most functions of this file as accesses to the
 266    struct gl_omap_implementation.  */
 267
 268 GL_OMAP_INLINE gl_omap_t
 269 gl_omap_nx_create_empty (gl_omap_implementation_t implementation,
 270                          gl_mapkey_compar_fn compar_fn,
 271                          gl_mapkey_dispose_fn kdispose_fn,
 272                          gl_mapvalue_dispose_fn vdispose_fn)
 273 {
 274   return implementation->nx_create_empty (implementation, compar_fn,
 275                                           kdispose_fn, vdispose_fn);
 276 }
 277
 278 GL_OMAP_INLINE size_t
 279 gl_omap_size (gl_omap_t map)
 280 {
 281   return ((const struct gl_omap_impl_base *) map)->vtable->size (map);
 282 }
 283
 284 GL_OMAP_INLINE bool
 285 gl_omap_search (gl_omap_t map, const void *key, const void **valuep)
 286 {
 287   return ((const struct gl_omap_impl_base *) map)->vtable
 288          ->search (map, key, valuep);
 289 }
 290
 291 GL_OMAP_INLINE bool
 292 gl_omap_search_atleast (gl_omap_t map,
 293                         gl_mapkey_threshold_fn threshold_fn,
 294                         const void *threshold,
 295                         const void **keyp, const void **valuep)
 296 {
 297   return ((const struct gl_omap_impl_base *) map)->vtable
 298          ->search_atleast (map, threshold_fn, threshold, keyp, valuep);
 299 }
 300
 301 GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 302 gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
 303                    const void **oldvaluep)
 304 {
 305   return ((const struct gl_omap_impl_base *) map)->vtable
 306          ->nx_getput (map, key, value, oldvaluep);
 307 }
 308
 309 GL_OMAP_INLINE bool
 310 gl_omap_getremove (gl_omap_t map, const void *key, const void **oldvaluep)
 311 {
 312   return ((const struct gl_omap_impl_base *) map)->vtable
 313          ->getremove (map, key, oldvaluep);
 314 }
 315
 316 GL_OMAP_INLINE void
 317 gl_omap_free (gl_omap_t map)
 318 {
 319   ((const struct gl_omap_impl_base *) map)->vtable->omap_free (map);
 320 }
 321
 322 GL_OMAP_INLINE gl_omap_iterator_t
 323 gl_omap_iterator (gl_omap_t map)
 324 {
 325   return ((const struct gl_omap_impl_base *) map)->vtable->iterator (map);
 326 }
 327
 328 GL_OMAP_INLINE bool
 329 gl_omap_iterator_next (gl_omap_iterator_t *iterator,
 330                        const void **keyp, const void **valuep)
 331 {
 332   return iterator->vtable->iterator_next (iterator, keyp, valuep);
 333 }
 334
 335 GL_OMAP_INLINE void
 336 gl_omap_iterator_free (gl_omap_iterator_t *iterator)
 337 {
 338   iterator->vtable->iterator_free (iterator);
 339 }
 340
 341 /* Define the convenience functions, that is, the functions that are independent
 342    of the implementation.  */
 343
 344 GL_OMAP_INLINE const void *
 345 gl_omap_get (gl_omap_t map, const void *key)
 346 {
 347   const void *value = NULL;
 348   gl_omap_search (map, key, &value);
 349   return value;
 350 }
 351
 352 GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 353 gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
 354 {
 355   const void *oldvalue;
 356   int result = gl_omap_nx_getput (map, key, value, &oldvalue);
 357   if (result == 0)
 358     {
 359       gl_mapvalue_dispose_fn vdispose_fn =
 360         ((const struct gl_omap_impl_base *) map)->vdispose_fn;
 361       if (vdispose_fn != NULL)
 362         vdispose_fn (oldvalue);
 363     }
 364   return result;
 365 }
 366
 367 GL_OMAP_INLINE bool
 368 gl_omap_remove (gl_omap_t map, const void *key)
 369 {
 370   const void *oldvalue;
 371   bool result = gl_omap_getremove (map, key, &oldvalue);
 372   if (result)
 373     {
 374       gl_mapvalue_dispose_fn vdispose_fn =
 375         ((const struct gl_omap_impl_base *) map)->vdispose_fn;
 376       if (vdispose_fn != NULL)
 377         vdispose_fn (oldvalue);
 378     }
 379   return result;
 380 }
 381
 382 #ifdef __cplusplus
 383 }
 384 #endif
 385
 386 _GL_INLINE_HEADER_END
 387
 388 #endif /* _GL_OMAP_H */