lib/gl_array_oset.c

   1 /* Ordered set data type implemented by an array.
   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 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "gl_array_oset.h"
  22
  23 #include <stdlib.h>
  24
  25 /* Checked size_t computations.  */
  26 #include "xsize.h"
  27
  28 /* -------------------------- gl_oset_t Data Type -------------------------- */
  29
  30 /* Concrete gl_oset_impl type, valid for this file only.  */
  31 struct gl_oset_impl
  32 {
  33   struct gl_oset_impl_base base;
  34   /* An array of ALLOCATED elements, of which the first COUNT are used.
  35      0 <= COUNT <= ALLOCATED.  */
  36   const void **elements;
  37   size_t count;
  38   size_t allocated;
  39 };
  40
  41 static gl_oset_t
  42 gl_array_nx_create_empty (gl_oset_implementation_t implementation,
  43                           gl_setelement_compar_fn compar_fn,
  44                           gl_setelement_dispose_fn dispose_fn)
  45 {
  46   struct gl_oset_impl *set =
  47     (struct gl_oset_impl *) malloc (sizeof (struct gl_oset_impl));
  48
  49   if (set == NULL)
  50     return NULL;
  51
  52   set->base.vtable = implementation;
  53   set->base.compar_fn = compar_fn;
  54   set->base.dispose_fn = dispose_fn;
  55   set->elements = NULL;
  56   set->count = 0;
  57   set->allocated = 0;
  58
  59   return set;
  60 }
  61
  62 static size_t
  63 gl_array_size (gl_oset_t set)
  64 {
  65   return set->count;
  66 }
  67
  68 static size_t
  69 gl_array_indexof (gl_oset_t set, const void *elt)
  70 {
  71   size_t count = set->count;
  72
  73   if (count > 0)
  74     {
  75       gl_setelement_compar_fn compar = set->base.compar_fn;
  76       size_t low = 0;
  77       size_t high = count;
  78
  79       /* At each loop iteration, low < high; for indices < low the values
  80          are smaller than ELT; for indices >= high the values are greater
  81          than ELT.  So, if the element occurs in the list, it is at
  82          low <= position < high.  */
  83       do
  84         {
  85           size_t mid = low + (high - low) / 2; /* low <= mid < high */
  86           int cmp = (compar != NULL
  87                      ? compar (set->elements[mid], elt)
  88                      : (set->elements[mid] > elt ? 1 :
  89                         set->elements[mid] < elt ? -1 : 0));
  90
  91           if (cmp < 0)
  92             low = mid + 1;
  93           else if (cmp > 0)
  94             high = mid;
  95           else /* cmp == 0 */
  96             /* We have an element equal to ELT at index MID.  */
  97             return mid;
  98         }
  99       while (low < high);
 100     }
 101   return (size_t)(-1);
 102 }
 103
 104 static bool
 105 gl_array_search (gl_oset_t set, const void *elt)
 106 {
 107   return gl_array_indexof (set, elt) != (size_t)(-1);
 108 }
 109
 110 static bool
 111 gl_array_search_atleast (gl_oset_t set,
 112                          gl_setelement_threshold_fn threshold_fn,
 113                          const void *threshold,
 114                          const void **eltp)
 115 {
 116   size_t count = set->count;
 117
 118   if (count > 0)
 119     {
 120       size_t low = 0;
 121       size_t high = count;
 122
 123       /* At each loop iteration, low < high; for indices < low the values are
 124          smaller than THRESHOLD; for indices >= high the values are nonexistent.
 125          So, if an element >= THRESHOLD occurs in the list, it is at
 126          low <= position < high.  */
 127       do
 128         {
 129           size_t mid = low + (high - low) / 2; /* low <= mid < high */
 130
 131           if (! threshold_fn (set->elements[mid], threshold))
 132             low = mid + 1;
 133           else
 134             {
 135               /* We have an element >= THRESHOLD at index MID.  But we need the
 136                  minimal such index.  */
 137               high = mid;
 138               /* At each loop iteration, low <= high and
 139                    compar (list->elements[high], value) >= 0,
 140                  and we know that the first occurrence of the element is at
 141                  low <= position <= high.  */
 142               while (low < high)
 143                 {
 144                   size_t mid2 = low + (high - low) / 2; /* low <= mid2 < high */
 145
 146                   if (! threshold_fn (set->elements[mid2], threshold))
 147                     low = mid2 + 1;
 148                   else
 149                     high = mid2;
 150                 }
 151               *eltp = set->elements[low];
 152               return true;
 153             }
 154         }
 155       while (low < high);
 156     }
 157   return false;
 158 }
 159
 160 /* Ensure that set->allocated > set->count.
 161    Return 0 upon success, -1 upon out-of-memory.  */
 162 static int
 163 grow (gl_oset_t set)
 164 {
 165   size_t new_allocated;
 166   size_t memory_size;
 167   const void **memory;
 168
 169   new_allocated = xtimes (set->allocated, 2);
 170   new_allocated = xsum (new_allocated, 1);
 171   memory_size = xtimes (new_allocated, sizeof (const void *));
 172   if (size_overflow_p (memory_size))
 173     /* Overflow, would lead to out of memory.  */
 174     return -1;
 175   memory = (const void **) realloc (set->elements, memory_size);
 176   if (memory == NULL)
 177     /* Out of memory.  */
 178     return -1;
 179   set->elements = memory;
 180   set->allocated = new_allocated;
 181   return 0;
 182 }
 183
 184 /* Add the given element ELT at the given position,
 185    0 <= position <= gl_oset_size (set).
 186    Return 1 upon success, -1 upon out-of-memory.  */
 187 static int
 188 gl_array_nx_add_at (gl_oset_t set, size_t position, const void *elt)
 189 {
 190   size_t count = set->count;
 191   const void **elements;
 192   size_t i;
 193
 194   if (count == set->allocated)
 195     if (grow (set) < 0)
 196       return -1;
 197   elements = set->elements;
 198   for (i = count; i > position; i--)
 199     elements[i] = elements[i - 1];
 200   elements[position] = elt;
 201   set->count = count + 1;
 202   return 1;
 203 }
 204
 205 /* Remove the element at the given position,
 206    0 <= position < gl_oset_size (set).  */
 207 static void
 208 gl_array_remove_at (gl_oset_t set, size_t position)
 209 {
 210   size_t count = set->count;
 211   const void **elements;
 212   size_t i;
 213
 214   elements = set->elements;
 215   if (set->base.dispose_fn != NULL)
 216     set->base.dispose_fn (elements[position]);
 217   for (i = position + 1; i < count; i++)
 218     elements[i - 1] = elements[i];
 219   set->count = count - 1;
 220 }
 221
 222 static int
 223 gl_array_nx_add (gl_oset_t set, const void *elt)
 224 {
 225   size_t count = set->count;
 226   size_t low = 0;
 227
 228   if (count > 0)
 229     {
 230       gl_setelement_compar_fn compar = set->base.compar_fn;
 231       size_t high = count;
 232
 233       /* At each loop iteration, low < high; for indices < low the values
 234          are smaller than ELT; for indices >= high the values are greater
 235          than ELT.  So, if the element occurs in the list, it is at
 236          low <= position < high.  */
 237       do
 238         {
 239           size_t mid = low + (high - low) / 2; /* low <= mid < high */
 240           int cmp = (compar != NULL
 241                      ? compar (set->elements[mid], elt)
 242                      : (set->elements[mid] > elt ? 1 :
 243                         set->elements[mid] < elt ? -1 : 0));
 244
 245           if (cmp < 0)
 246             low = mid + 1;
 247           else if (cmp > 0)
 248             high = mid;
 249           else /* cmp == 0 */
 250             return false;
 251         }
 252       while (low < high);
 253     }
 254   return gl_array_nx_add_at (set, low, elt);
 255 }
 256
 257 static bool
 258 gl_array_remove (gl_oset_t set, const void *elt)
 259 {
 260   size_t index = gl_array_indexof (set, elt);
 261   if (index != (size_t)(-1))
 262     {
 263       gl_array_remove_at (set, index);
 264       return true;
 265     }
 266   else
 267     return false;
 268 }
 269
 270 static void
 271 gl_array_free (gl_oset_t set)
 272 {
 273   if (set->elements != NULL)
 274     {
 275       if (set->base.dispose_fn != NULL)
 276         {
 277           size_t count = set->count;
 278
 279           if (count > 0)
 280             {
 281               gl_setelement_dispose_fn dispose = set->base.dispose_fn;
 282               const void **elements = set->elements;
 283
 284               do
 285                 dispose (*elements++);
 286               while (--count > 0);
 287             }
 288         }
 289       free (set->elements);
 290     }
 291   free (set);
 292 }
 293
 294 /* --------------------- gl_oset_iterator_t Data Type --------------------- */
 295
 296 static gl_oset_iterator_t
 297 gl_array_iterator (gl_oset_t set)
 298 {
 299   gl_oset_iterator_t result;
 300
 301   result.vtable = set->base.vtable;
 302   result.set = set;
 303   result.count = set->count;
 304   result.p = set->elements + 0;
 305   result.q = set->elements + set->count;
 306 #if defined GCC_LINT || defined lint
 307   result.i = 0;
 308   result.j = 0;
 309 #endif
 310
 311   return result;
 312 }
 313
 314 static bool
 315 gl_array_iterator_next (gl_oset_iterator_t *iterator, const void **eltp)
 316 {
 317   gl_oset_t set = iterator->set;
 318   if (iterator->count != set->count)
 319     {
 320       if (iterator->count != set->count + 1)
 321         /* Concurrent modifications were done on the set.  */
 322         abort ();
 323       /* The last returned element was removed.  */
 324       iterator->count--;
 325       iterator->p = (const void **) iterator->p - 1;
 326       iterator->q = (const void **) iterator->q - 1;
 327     }
 328   if (iterator->p < iterator->q)
 329     {
 330       const void **p = (const void **) iterator->p;
 331       *eltp = *p;
 332       iterator->p = p + 1;
 333       return true;
 334     }
 335   else
 336     return false;
 337 }
 338
 339 static void
 340 gl_array_iterator_free (gl_oset_iterator_t *iterator)
 341 {
 342 }
 343
 344
 345 const struct gl_oset_implementation gl_array_oset_implementation =
 346   {
 347     gl_array_nx_create_empty,
 348     gl_array_size,
 349     gl_array_search,
 350     gl_array_search_atleast,
 351     gl_array_nx_add,
 352     gl_array_remove,
 353     gl_array_free,
 354     gl_array_iterator,
 355     gl_array_iterator_next,
 356     gl_array_iterator_free
 357   };