glib/gbsearcharray.h

   1 /* GBSearchArray - Binary Searchable Array implementation
   2  * Copyright (C) 2000-2003 Tim Janik
   3  *
   4  * This software is provided "as is"; redistribution and modification
   5  * is permitted, provided that the following disclaimer is retained.
   6  *
   7  * This software is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  10  * In no event shall the authors or contributors be liable for any
  11  * direct, indirect, incidental, special, exemplary, or consequential
  12  * damages (including, but not limited to, procurement of substitute
  13  * goods or services; loss of use, data, or profits; or business
  14  * interruption) however caused and on any theory of liability, whether
  15  * in contract, strict liability, or tort (including negligence or
  16  * otherwise) arising in any way out of the use of this software, even
  17  * if advised of the possibility of such damage.
  18  */
  19 #ifndef __G_BSEARCH_ARRAY_H__
  20 #define __G_BSEARCH_ARRAY_H__
  21
  22 #include <glib.h>
  23 #include <string.h>
  24
  25
  26 G_BEGIN_DECLS   /* c++ guards */
  27
  28 /* this implementation is intended to be usable in third-party code
  29  * simply by pasting the contents of this file. as such, the
  30  * implementation needs to be self-contained within this file.
  31  */
  32
  33 /* convenience macro to avoid signed overflow for value comparisons */
  34 #define G_BSEARCH_ARRAY_CMP(v1,v2) ((v1) > (v2) ? +1 : (v1) == (v2) ? 0 : -1)
  35
  36
  37 /* --- typedefs --- */
  38 typedef gint  (*GBSearchCompareFunc) (gconstpointer bsearch_node1, /* key */
  39                                       gconstpointer bsearch_node2);
  40 typedef enum
  41 {
  42   G_BSEARCH_ARRAY_ALIGN_POWER2  = 1 << 0, /* align memory to power2 sizes */
  43   G_BSEARCH_ARRAY_AUTO_SHRINK  = 1 << 1   /* shrink array upon removal */
  44 } GBSearchArrayFlags;
  45
  46
  47 /* --- structures --- */
  48 typedef struct
  49 {
  50   guint               sizeof_node;
  51   GBSearchCompareFunc cmp_nodes;
  52   guint               flags;
  53 } GBSearchConfig;
  54 typedef union
  55 {
  56   guint    n_nodes;
  57   /*< private >*/
  58   gpointer alignment_dummy1;
  59   glong    alignment_dummy2;
  60   gdouble  alignment_dummy3;
  61 } GBSearchArray;
  62
  63
  64 /* --- public API --- */
  65 static inline GBSearchArray*    g_bsearch_array_create    (const GBSearchConfig *bconfig);
  66 static inline gpointer          g_bsearch_array_get_nth   (GBSearchArray        *barray,
  67                                                            const GBSearchConfig *bconfig,
  68                                                            guint                 nth);
  69 static inline guint             g_bsearch_array_get_index (GBSearchArray        *barray,
  70                                                            const GBSearchConfig *bconfig,
  71                                                            gconstpointer         node_in_array);
  72 static inline GBSearchArray*    g_bsearch_array_remove    (GBSearchArray        *barray,
  73                                                            const GBSearchConfig *bconfig,
  74                                                            guint                 index_);
  75 /* provide uninitialized space at index for node insertion */
  76 static inline GBSearchArray*    g_bsearch_array_grow      (GBSearchArray        *barray,
  77                                                            const GBSearchConfig *bconfig,
  78                                                            guint                 index);
  79 /* insert key_node into array if it does not exist, otherwise do nothing */
  80 static inline GBSearchArray*    g_bsearch_array_insert    (GBSearchArray        *barray,
  81                                                            const GBSearchConfig *bconfig,
  82                                                            gconstpointer         key_node);
  83 /* insert key_node into array if it does not exist,
  84  * otherwise replace the existing node's contents with key_node
  85  */
  86 static inline GBSearchArray*    g_bsearch_array_replace   (GBSearchArray        *barray,
  87                                                            const GBSearchConfig *bconfig,
  88                                                            gconstpointer         key_node);
  89 static inline void              g_bsearch_array_free      (GBSearchArray        *barray,
  90                                                            const GBSearchConfig *bconfig);
  91 #define g_bsearch_array_get_n_nodes(barray)     (((GBSearchArray*) (barray))->n_nodes)
  92
  93 /* g_bsearch_array_lookup():
  94  * return NULL or exact match node
  95  */
  96 #define g_bsearch_array_lookup(barray, bconfig, key_node)       \
  97     g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 0)
  98
  99 /* g_bsearch_array_lookup_sibling():
 100  * return NULL for barray->n_nodes==0, otherwise return the
 101  * exact match node, or, if there's no such node, return the
 102  * node last visited, which is pretty close to an exact match
 103  * (will be one off into either direction).
 104  */
 105 #define g_bsearch_array_lookup_sibling(barray, bconfig, key_node)       \
 106     g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 1)
 107
 108 /* g_bsearch_array_lookup_insertion():
 109  * return NULL for barray->n_nodes==0 or exact match, otherwise
 110  * return the node where key_node should be inserted (may be one
 111  * after end, i.e. g_bsearch_array_get_index(result) <= barray->n_nodes).
 112  */
 113 #define g_bsearch_array_lookup_insertion(barray, bconfig, key_node)     \
 114     g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 2)
 115
 116
 117 /* --- implementation --- */
 118 /* helper macro to cut down realloc()s */
 119 #define G_BSEARCH_UPPER_POWER2(n)       ((n) ? 1 << g_bit_storage ((n) - 1) : 0)
 120 #define G_BSEARCH_ARRAY_NODES(barray)    (((guint8*) (barray)) + sizeof (GBSearchArray))
 121 static inline GBSearchArray*
 122 g_bsearch_array_create (const GBSearchConfig *bconfig)
 123 {
 124   GBSearchArray *barray;
 125   guint size;
 126
 127   g_return_val_if_fail (bconfig != NULL, NULL);
 128
 129   size = sizeof (GBSearchArray) + bconfig->sizeof_node;
 130   if (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2)
 131     size = G_BSEARCH_UPPER_POWER2 (size);
 132   barray = (GBSearchArray *) g_malloc (size);
 133   memset (barray, 0, sizeof (GBSearchArray));
 134
 135   return barray;
 136 }
 137 static inline gpointer
 138 g_bsearch_array_lookup_fuzzy (GBSearchArray             *barray,
 139                               const GBSearchConfig      *bconfig,
 140                               gconstpointer              key_node,
 141                               const guint                sibling_or_after);
 142 static inline gpointer
 143 g_bsearch_array_lookup_fuzzy (GBSearchArray        *barray,
 144                               const GBSearchConfig *bconfig,
 145                               gconstpointer         key_node,
 146                               const guint           sibling_or_after)
 147 {
 148   GBSearchCompareFunc cmp_nodes = bconfig->cmp_nodes;
 149   guint8 *check = NULL, *nodes = G_BSEARCH_ARRAY_NODES (barray);
 150   guint n_nodes = barray->n_nodes, offs = 0;
 151   guint sizeof_node = bconfig->sizeof_node;
 152   gint cmp = 0;
 153
 154   while (offs < n_nodes)
 155     {
 156       guint i = (offs + n_nodes) >> 1;
 157
 158       check = nodes + i * sizeof_node;
 159       cmp = cmp_nodes (key_node, check);
 160       if (cmp == 0)
 161         return sibling_or_after > 1 ? NULL : check;
 162       else if (cmp < 0)
 163         n_nodes = i;
 164       else /* (cmp > 0) */
 165         offs = i + 1;
 166     }
 167
 168   /* check is last mismatch, cmp > 0 indicates greater key */
 169   return G_LIKELY (!sibling_or_after) ? NULL : (sibling_or_after > 1 && cmp > 0) ? check + sizeof_node : check;
 170 }
 171 static inline gpointer
 172 g_bsearch_array_get_nth (GBSearchArray        *barray,
 173                          const GBSearchConfig *bconfig,
 174                          guint                 nth)
 175 {
 176   return (G_LIKELY (nth < barray->n_nodes) ?
 177           G_BSEARCH_ARRAY_NODES (barray) + nth * bconfig->sizeof_node :
 178           NULL);
 179 }
 180 static inline guint
 181 g_bsearch_array_get_index (GBSearchArray        *barray,
 182                            const GBSearchConfig *bconfig,
 183                            gconstpointer         node_in_array)
 184 {
 185   guint distance = ((guint8*) node_in_array) - G_BSEARCH_ARRAY_NODES (barray);
 186
 187   g_return_val_if_fail (node_in_array != NULL, barray->n_nodes);
 188
 189   distance /= bconfig->sizeof_node;
 190
 191   return MIN (distance, barray->n_nodes + 1); /* may return one after end */
 192 }
 193 static inline GBSearchArray*
 194 g_bsearch_array_grow (GBSearchArray        *barray,
 195                       const GBSearchConfig *bconfig,
 196                       guint                 index_)
 197 {
 198   guint old_size = barray->n_nodes * bconfig->sizeof_node;
 199   guint new_size = old_size + bconfig->sizeof_node;
 200   guint8 *node;
 201
 202   g_return_val_if_fail (index_ <= barray->n_nodes, NULL);
 203
 204   if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2))
 205     {
 206       new_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + new_size);
 207       old_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + old_size);
 208       if (old_size != new_size)
 209         barray = (GBSearchArray *) g_realloc (barray, new_size);
 210     }
 211   else
 212     barray = (GBSearchArray *) g_realloc (barray, sizeof (GBSearchArray) + new_size);
 213   node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;
 214   memmove (node + bconfig->sizeof_node, node, (barray->n_nodes - index_) * bconfig->sizeof_node);
 215   barray->n_nodes += 1;
 216   return barray;
 217 }
 218 static inline GBSearchArray*
 219 g_bsearch_array_insert (GBSearchArray        *barray,
 220                         const GBSearchConfig *bconfig,
 221                         gconstpointer         key_node)
 222 {
 223   guint8 *node;
 224
 225   if (G_UNLIKELY (!barray->n_nodes))
 226     {
 227       barray = g_bsearch_array_grow (barray, bconfig, 0);
 228       node = G_BSEARCH_ARRAY_NODES (barray);
 229     }
 230   else
 231     {
 232       node = (guint8 *) g_bsearch_array_lookup_insertion (barray, bconfig, key_node);
 233       if (G_LIKELY (node))
 234         {
 235           guint index_ = g_bsearch_array_get_index (barray, bconfig, node);
 236
 237           /* grow and insert */
 238           barray = g_bsearch_array_grow (barray, bconfig, index_);
 239           node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;
 240         }
 241       else /* no insertion needed, node already there */
 242         return barray;
 243     }
 244   memcpy (node, key_node, bconfig->sizeof_node);
 245   return barray;
 246 }
 247 static inline GBSearchArray*
 248 g_bsearch_array_replace (GBSearchArray        *barray,
 249                          const GBSearchConfig *bconfig,
 250                          gconstpointer         key_node)
 251 {
 252   guint8 *node = (guint8 *) g_bsearch_array_lookup (barray, bconfig, key_node);
 253   if (G_LIKELY (node))  /* expected path */
 254     memcpy (node, key_node, bconfig->sizeof_node);
 255   else                  /* revert to insertion */
 256     barray = g_bsearch_array_insert (barray, bconfig, key_node);
 257   return barray;
 258 }
 259 static inline GBSearchArray*
 260 g_bsearch_array_remove (GBSearchArray        *barray,
 261                         const GBSearchConfig *bconfig,
 262                         guint                 index_)
 263 {
 264   guint8 *node;
 265
 266   g_return_val_if_fail (index_ < barray->n_nodes, NULL);
 267
 268   barray->n_nodes -= 1;
 269   node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;
 270   memmove (node, node + bconfig->sizeof_node, (barray->n_nodes - index_) * bconfig->sizeof_node);
 271   if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_AUTO_SHRINK))
 272     {
 273       guint new_size = barray->n_nodes * bconfig->sizeof_node;
 274       guint old_size = new_size + bconfig->sizeof_node;
 275
 276       if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2))
 277         {
 278           new_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + new_size);
 279           old_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + old_size);
 280           if (old_size != new_size)
 281             barray = (GBSearchArray *) g_realloc (barray, new_size);
 282         }
 283       else
 284         barray = (GBSearchArray *) g_realloc (barray, sizeof (GBSearchArray) + new_size);
 285     }
 286   return barray;
 287 }
 288 static inline void
 289 g_bsearch_array_free (GBSearchArray        *barray,
 290                       const GBSearchConfig *bconfig)
 291 {
 292   g_return_if_fail (barray != NULL);
 293
 294   g_free (barray);
 295 }
 296
 297 G_END_DECLS     /* c++ guards */
 298
 299 #endif  /* !__G_BSEARCH_ARRAY_H__ */