lib/gl_oset.h

   1 /* Abstract ordered set data type.
   2    Copyright (C) 2006-2007, 2009-2018 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2006.
   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_OSET_H
  19 #define _GL_OSET_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_OSET_INLINE
  29 # define GL_OSET_INLINE _GL_INLINE
  30 #endif
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36
  37 /* gl_oset is an abstract ordered set data type.  It can contain any number
  38    of objects ('void *' or 'const void *' pointers) in the order of a given
  39    comparator function.  Duplicates (in the sense of the comparator) are
  40    forbidden.
  41
  42    There are several implementations of this ordered set datatype, optimized
  43    for different operations or for memory.  You can start using the simplest
  44    ordered set implementation, GL_ARRAY_OSET, and switch to a different
  45    implementation later, when you realize which operations are performed
  46    the most frequently.  The API of the different implementations is exactly
  47    the same; when switching to a different implementation, you only have to
  48    change the gl_oset_create call.
  49
  50    The implementations are:
  51      GL_ARRAY_OSET        a growable array
  52      GL_AVLTREE_OSET      a binary tree (AVL tree)
  53      GL_RBTREE_OSET       a binary tree (red-black tree)
  54
  55    The memory consumption is asymptotically the same: O(1) for every object
  56    in the set.  When looking more closely at the average memory consumed
  57    for an object, GL_ARRAY_OSET is the most compact representation, and
  58    GL_AVLTREE_OSET, GL_RBTREE_OSET need more memory.
  59
  60    The guaranteed average performance of the operations is, for a set of
  61    n elements:
  62
  63    Operation                  ARRAY     TREE
  64
  65    gl_oset_size                O(1)     O(1)
  66    gl_oset_add                 O(n)   O(log n)
  67    gl_oset_remove              O(n)   O(log n)
  68    gl_oset_search            O(log n) O(log n)
  69    gl_oset_search_atleast    O(log n) O(log n)
  70    gl_oset_iterator            O(1)   O(log n)
  71    gl_oset_iterator_next       O(1)   O(log n)
  72  */
  73
  74 /* -------------------------- gl_oset_t Data Type -------------------------- */
  75
  76 /* Type of function used to compare two elements.  Same as for qsort().
  77    NULL denotes pointer comparison.  */
  78 typedef int (*gl_setelement_compar_fn) (const void *elt1, const void *elt2);
  79
  80 #ifndef _GL_SETELEMENT_DISPOSE_FN_DEFINED
  81 /* Type of function used to dispose an element once it's removed from a set.
  82    NULL denotes a no-op.  */
  83 typedef void (*gl_setelement_dispose_fn) (const void *elt);
  84 # define _GL_SETELEMENT_DISPOSE_FN_DEFINED 1
  85 #endif
  86
  87 /* Type of function used to compare an element with a threshold.
  88    Return true if the element is greater or equal than the threshold.  */
  89 typedef bool (*gl_setelement_threshold_fn) (const void *elt, const void *threshold);
  90
  91 struct gl_oset_impl;
  92 /* Type representing an entire ordered set.  */
  93 typedef struct gl_oset_impl * gl_oset_t;
  94
  95 struct gl_oset_implementation;
  96 /* Type representing a ordered set datatype implementation.  */
  97 typedef const struct gl_oset_implementation * gl_oset_implementation_t;
  98
  99 #if 0 /* Unless otherwise specified, these are defined inline below.  */
 100
 101 /* Create an empty set.
 102    IMPLEMENTATION is one of GL_ARRAY_OSET, GL_AVLTREE_OSET, GL_RBTREE_OSET.
 103    COMPAR_FN is an element comparison function or NULL.
 104    DISPOSE_FN is an element disposal function or NULL.  */
 105 /* declared in gl_xoset.h */
 106 extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
 107                                        gl_setelement_compar_fn compar_fn,
 108                                        gl_setelement_dispose_fn dispose_fn);
 109 /* Likewise.  Return NULL upon out-of-memory.  */
 110 extern gl_oset_t gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
 111                                           gl_setelement_compar_fn compar_fn,
 112                                           gl_setelement_dispose_fn dispose_fn);
 113
 114 /* Return the current number of elements in an ordered set.  */
 115 extern size_t gl_oset_size (gl_oset_t set);
 116
 117 /* Search whether an element is already in the ordered set.
 118    Return true if found, or false if not present in the set.  */
 119 extern bool gl_oset_search (gl_oset_t set, const void *elt);
 120
 121 /* Search the least element in the ordered set that compares greater or equal
 122    to the given THRESHOLD.  The representation of the THRESHOLD is defined
 123    by the THRESHOLD_FN.
 124    Return true and store the found element in *ELTP if found, otherwise return
 125    false.  */
 126 extern bool gl_oset_search_atleast (gl_oset_t set,
 127                                     gl_setelement_threshold_fn threshold_fn,
 128                                     const void *threshold,
 129                                     const void **eltp);
 130
 131 /* Add an element to an ordered set.
 132    Return true if it was not already in the set and added, false otherwise.  */
 133 /* declared in gl_xoset.h */
 134 extern bool gl_oset_add (gl_oset_t set, const void *elt);
 135 /* Likewise.  Return -1 upon out-of-memory.  */
 136 extern int gl_oset_nx_add (gl_oset_t set, const void *elt)
 137 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 138   __attribute__ ((__warn_unused_result__))
 139 #endif
 140   ;
 141
 142 /* Remove an element from an ordered set.
 143    Return true if it was found and removed.  */
 144 extern bool gl_oset_remove (gl_oset_t set, const void *elt);
 145
 146 /* Free an entire ordered set.
 147    (But this call does not free the elements of the set.)  */
 148 extern void gl_oset_free (gl_oset_t set);
 149
 150 #endif /* End of inline and gl_xoset.h-defined functions.  */
 151
 152 /* --------------------- gl_oset_iterator_t Data Type --------------------- */
 153
 154 /* Functions for iterating through an ordered set.  */
 155
 156 /* Type of an iterator that traverses an ordered set.
 157    This is a fixed-size struct, so that creation of an iterator doesn't need
 158    memory allocation on the heap.  */
 159 typedef struct
 160 {
 161   /* For fast dispatch of gl_oset_iterator_next.  */
 162   const struct gl_oset_implementation *vtable;
 163   /* For detecting whether the last returned element was removed.  */
 164   gl_oset_t set;
 165   size_t count;
 166   /* Other, implementation-private fields.  */
 167   void *p; void *q;
 168   size_t i; size_t j;
 169 } gl_oset_iterator_t;
 170
 171 #if 0 /* These are defined inline below.  */
 172
 173 /* Create an iterator traversing an ordered set.
 174    The set's contents must not be modified while the iterator is in use,
 175    except for removing the last returned element.  */
 176 extern gl_oset_iterator_t gl_oset_iterator (gl_oset_t set);
 177
 178 /* If there is a next element, store the next element in *ELTP, advance the
 179    iterator and return true.  Otherwise, return false.  */
 180 extern bool gl_oset_iterator_next (gl_oset_iterator_t *iterator,
 181                                    const void **eltp);
 182
 183 /* Free an iterator.  */
 184 extern void gl_oset_iterator_free (gl_oset_iterator_t *iterator);
 185
 186 #endif /* End of inline functions.  */
 187
 188 /* ------------------------ Implementation Details ------------------------ */
 189
 190 struct gl_oset_implementation
 191 {
 192   /* gl_oset_t functions.  */
 193   gl_oset_t (*nx_create_empty) (gl_oset_implementation_t implementation,
 194                                 gl_setelement_compar_fn compar_fn,
 195                                 gl_setelement_dispose_fn dispose_fn);
 196   size_t (*size) (gl_oset_t set);
 197   bool (*search) (gl_oset_t set, const void *elt);
 198   bool (*search_atleast) (gl_oset_t set,
 199                           gl_setelement_threshold_fn threshold_fn,
 200                           const void *threshold, const void **eltp);
 201   int (*nx_add) (gl_oset_t set, const void *elt);
 202   bool (*remove_elt) (gl_oset_t set, const void *elt);
 203   void (*oset_free) (gl_oset_t set);
 204   /* gl_oset_iterator_t functions.  */
 205   gl_oset_iterator_t (*iterator) (gl_oset_t set);
 206   bool (*iterator_next) (gl_oset_iterator_t *iterator, const void **eltp);
 207   void (*iterator_free) (gl_oset_iterator_t *iterator);
 208 };
 209
 210 struct gl_oset_impl_base
 211 {
 212   const struct gl_oset_implementation *vtable;
 213   gl_setelement_compar_fn compar_fn;
 214   gl_setelement_dispose_fn dispose_fn;
 215 };
 216
 217 /* Define all functions of this file as accesses to the
 218    struct gl_oset_implementation.  */
 219
 220 GL_OSET_INLINE gl_oset_t
 221 gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
 222                          gl_setelement_compar_fn compar_fn,
 223                          gl_setelement_dispose_fn dispose_fn)
 224 {
 225   return implementation->nx_create_empty (implementation, compar_fn,
 226                                           dispose_fn);
 227 }
 228
 229 GL_OSET_INLINE size_t
 230 gl_oset_size (gl_oset_t set)
 231 {
 232   return ((const struct gl_oset_impl_base *) set)->vtable->size (set);
 233 }
 234
 235 GL_OSET_INLINE bool
 236 gl_oset_search (gl_oset_t set, const void *elt)
 237 {
 238   return ((const struct gl_oset_impl_base *) set)->vtable->search (set, elt);
 239 }
 240
 241 GL_OSET_INLINE bool
 242 gl_oset_search_atleast (gl_oset_t set,
 243                         gl_setelement_threshold_fn threshold_fn,
 244                         const void *threshold, const void **eltp)
 245 {
 246   return ((const struct gl_oset_impl_base *) set)->vtable
 247          ->search_atleast (set, threshold_fn, threshold, eltp);
 248 }
 249
 250 GL_OSET_INLINE int
 251 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 252   __attribute__ ((__warn_unused_result__))
 253 #endif
 254 gl_oset_nx_add (gl_oset_t set, const void *elt)
 255 {
 256   return ((const struct gl_oset_impl_base *) set)->vtable->nx_add (set, elt);
 257 }
 258
 259 GL_OSET_INLINE bool
 260 gl_oset_remove (gl_oset_t set, const void *elt)
 261 {
 262   return ((const struct gl_oset_impl_base *) set)->vtable
 263          ->remove_elt (set, elt);
 264 }
 265
 266 GL_OSET_INLINE void
 267 gl_oset_free (gl_oset_t set)
 268 {
 269   ((const struct gl_oset_impl_base *) set)->vtable->oset_free (set);
 270 }
 271
 272 GL_OSET_INLINE gl_oset_iterator_t
 273 gl_oset_iterator (gl_oset_t set)
 274 {
 275   return ((const struct gl_oset_impl_base *) set)->vtable->iterator (set);
 276 }
 277
 278 GL_OSET_INLINE bool
 279 gl_oset_iterator_next (gl_oset_iterator_t *iterator, const void **eltp)
 280 {
 281   return iterator->vtable->iterator_next (iterator, eltp);
 282 }
 283
 284 GL_OSET_INLINE void
 285 gl_oset_iterator_free (gl_oset_iterator_t *iterator)
 286 {
 287   iterator->vtable->iterator_free (iterator);
 288 }
 289
 290 #ifdef __cplusplus
 291 }
 292 #endif
 293
 294 _GL_INLINE_HEADER_END
 295
 296 #endif /* _GL_OSET_H */