lib/gl_oset.h

   1 /* Abstract ordered set data type.
   2    Copyright (C) 2006-2007, 2009-2017 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 /* Type of function used to dispose an element once it's removed from a set.
  81    NULL denotes a no-op.  */
  82 typedef void (*gl_setelement_dispose_fn) (const void *elt);
  83
  84 /* Type of function used to compare an element with a threshold.
  85    Return true if the element is greater or equal than the threshold.  */
  86 typedef bool (*gl_setelement_threshold_fn) (const void *elt, const void *threshold);
  87
  88 struct gl_oset_impl;
  89 /* Type representing an entire ordered set.  */
  90 typedef struct gl_oset_impl * gl_oset_t;
  91
  92 struct gl_oset_implementation;
  93 /* Type representing a ordered set datatype implementation.  */
  94 typedef const struct gl_oset_implementation * gl_oset_implementation_t;
  95
  96 #if 0 /* Unless otherwise specified, these are defined inline below.  */
  97
  98 /* Create an empty set.
  99    IMPLEMENTATION is one of GL_ARRAY_OSET, GL_AVLTREE_OSET, GL_RBTREE_OSET.
 100    COMPAR_FN is an element comparison function or NULL.
 101    DISPOSE_FN is an element disposal function or NULL.  */
 102 /* declared in gl_xoset.h */
 103 extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
 104                                        gl_setelement_compar_fn compar_fn,
 105                                        gl_setelement_dispose_fn dispose_fn);
 106 /* Likewise.  Return NULL upon out-of-memory.  */
 107 extern gl_oset_t gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
 108                                           gl_setelement_compar_fn compar_fn,
 109                                           gl_setelement_dispose_fn dispose_fn);
 110
 111 /* Return the current number of elements in an ordered set.  */
 112 extern size_t gl_oset_size (gl_oset_t set);
 113
 114 /* Search whether an element is already in the ordered set.
 115    Return true if found, or false if not present in the set.  */
 116 extern bool gl_oset_search (gl_oset_t set, const void *elt);
 117
 118 /* Search the least element in the ordered set that compares greater or equal
 119    to the given THRESHOLD.  The representation of the THRESHOLD is defined
 120    by the THRESHOLD_FN.
 121    Return true and store the found element in *ELTP if found, otherwise return
 122    false.  */
 123 extern bool gl_oset_search_atleast (gl_oset_t set,
 124                                     gl_setelement_threshold_fn threshold_fn,
 125                                     const void *threshold,
 126                                     const void **eltp);
 127
 128 /* Add an element to an ordered set.
 129    Return true if it was not already in the set and added, false otherwise.  */
 130 /* declared in gl_xoset.h */
 131 extern bool gl_oset_add (gl_oset_t set, const void *elt);
 132 /* Likewise.  Return -1 upon out-of-memory.  */
 133 extern int gl_oset_nx_add (gl_oset_t set, const void *elt)
 134 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 135   __attribute__ ((__warn_unused_result__))
 136 #endif
 137   ;
 138
 139 /* Remove an element from an ordered set.
 140    Return true if it was found and removed.  */
 141 extern bool gl_oset_remove (gl_oset_t set, const void *elt);
 142
 143 /* Free an entire ordered set.
 144    (But this call does not free the elements of the set.)  */
 145 extern void gl_oset_free (gl_oset_t set);
 146
 147 #endif /* End of inline and gl_xlist.h-defined functions.  */
 148
 149 /* --------------------- gl_oset_iterator_t Data Type --------------------- */
 150
 151 /* Functions for iterating through an ordered set.  */
 152
 153 /* Type of an iterator that traverses an ordered set.
 154    This is a fixed-size struct, so that creation of an iterator doesn't need
 155    memory allocation on the heap.  */
 156 typedef struct
 157 {
 158   /* For fast dispatch of gl_oset_iterator_next.  */
 159   const struct gl_oset_implementation *vtable;
 160   /* For detecting whether the last returned element was removed.  */
 161   gl_oset_t set;
 162   size_t count;
 163   /* Other, implementation-private fields.  */
 164   void *p; void *q;
 165   size_t i; size_t j;
 166 } gl_oset_iterator_t;
 167
 168 #if 0 /* These are defined inline below.  */
 169
 170 /* Create an iterator traversing an ordered set.
 171    The set's contents must not be modified while the iterator is in use,
 172    except for removing the last returned element.  */
 173 extern gl_oset_iterator_t gl_oset_iterator (gl_oset_t set);
 174
 175 /* If there is a next element, store the next element in *ELTP, advance the
 176    iterator and return true.  Otherwise, return false.  */
 177 extern bool gl_oset_iterator_next (gl_oset_iterator_t *iterator,
 178                                    const void **eltp);
 179
 180 /* Free an iterator.  */
 181 extern void gl_oset_iterator_free (gl_oset_iterator_t *iterator);
 182
 183 #endif /* End of inline functions.  */
 184
 185 /* ------------------------ Implementation Details ------------------------ */
 186
 187 struct gl_oset_implementation
 188 {
 189   /* gl_oset_t functions.  */
 190   gl_oset_t (*nx_create_empty) (gl_oset_implementation_t implementation,
 191                                 gl_setelement_compar_fn compar_fn,
 192                                 gl_setelement_dispose_fn dispose_fn);
 193   size_t (*size) (gl_oset_t set);
 194   bool (*search) (gl_oset_t set, const void *elt);
 195   bool (*search_atleast) (gl_oset_t set,
 196                           gl_setelement_threshold_fn threshold_fn,
 197                           const void *threshold, const void **eltp);
 198   int (*nx_add) (gl_oset_t set, const void *elt);
 199   bool (*remove_elt) (gl_oset_t set, const void *elt);
 200   void (*oset_free) (gl_oset_t set);
 201   /* gl_oset_iterator_t functions.  */
 202   gl_oset_iterator_t (*iterator) (gl_oset_t set);
 203   bool (*iterator_next) (gl_oset_iterator_t *iterator, const void **eltp);
 204   void (*iterator_free) (gl_oset_iterator_t *iterator);
 205 };
 206
 207 struct gl_oset_impl_base
 208 {
 209   const struct gl_oset_implementation *vtable;
 210   gl_setelement_compar_fn compar_fn;
 211   gl_setelement_dispose_fn dispose_fn;
 212 };
 213
 214 /* Define all functions of this file as accesses to the
 215    struct gl_oset_implementation.  */
 216
 217 GL_OSET_INLINE gl_oset_t
 218 gl_oset_nx_create_empty (gl_oset_implementation_t implementation,
 219                          gl_setelement_compar_fn compar_fn,
 220                          gl_setelement_dispose_fn dispose_fn)
 221 {
 222   return implementation->nx_create_empty (implementation, compar_fn,
 223                                           dispose_fn);
 224 }
 225
 226 GL_OSET_INLINE size_t
 227 gl_oset_size (gl_oset_t set)
 228 {
 229   return ((const struct gl_oset_impl_base *) set)->vtable->size (set);
 230 }
 231
 232 GL_OSET_INLINE bool
 233 gl_oset_search (gl_oset_t set, const void *elt)
 234 {
 235   return ((const struct gl_oset_impl_base *) set)->vtable->search (set, elt);
 236 }
 237
 238 GL_OSET_INLINE bool
 239 gl_oset_search_atleast (gl_oset_t set,
 240                         gl_setelement_threshold_fn threshold_fn,
 241                         const void *threshold, const void **eltp)
 242 {
 243   return ((const struct gl_oset_impl_base *) set)->vtable
 244          ->search_atleast (set, threshold_fn, threshold, eltp);
 245 }
 246
 247 GL_OSET_INLINE int
 248 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 249   __attribute__ ((__warn_unused_result__))
 250 #endif
 251 gl_oset_nx_add (gl_oset_t set, const void *elt)
 252 {
 253   return ((const struct gl_oset_impl_base *) set)->vtable->nx_add (set, elt);
 254 }
 255
 256 GL_OSET_INLINE bool
 257 gl_oset_remove (gl_oset_t set, const void *elt)
 258 {
 259   return ((const struct gl_oset_impl_base *) set)->vtable
 260          ->remove_elt (set, elt);
 261 }
 262
 263 GL_OSET_INLINE void
 264 gl_oset_free (gl_oset_t set)
 265 {
 266   ((const struct gl_oset_impl_base *) set)->vtable->oset_free (set);
 267 }
 268
 269 GL_OSET_INLINE gl_oset_iterator_t
 270 gl_oset_iterator (gl_oset_t set)
 271 {
 272   return ((const struct gl_oset_impl_base *) set)->vtable->iterator (set);
 273 }
 274
 275 GL_OSET_INLINE bool
 276 gl_oset_iterator_next (gl_oset_iterator_t *iterator, const void **eltp)
 277 {
 278   return iterator->vtable->iterator_next (iterator, eltp);
 279 }
 280
 281 GL_OSET_INLINE void
 282 gl_oset_iterator_free (gl_oset_iterator_t *iterator)
 283 {
 284   iterator->vtable->iterator_free (iterator);
 285 }
 286
 287 #ifdef __cplusplus
 288 }
 289 #endif
 290
 291 _GL_INLINE_HEADER_END
 292
 293 #endif /* _GL_OSET_H */