index.c

   1 /* ################################################################### */
   2 /* Copyright 2015, Pierre Gentile (p.gen.progs@gmail.com)              */
   3 /*                                                                     */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public */
   5 /* License, v. 2.0. If a copy of the MPL was not distributed with this */
   6 /* file, You can obtain one at https://mozilla.org/MPL/2.0/.           */
   7 /* ################################################################### */
   8
   9 /* ************************************************************************ */
  10 /* Ternary Search Tree and sorted array creation functions.                 */
  11 /* Inspired by a code described in "Ternary Search Trees" by Jon            */
  12 /* Bentley and Robert Sedgewick in the April, 1998, Dr. Dobb's Journal.     */
  13 /* Links:                                                                   */
  14 /*   https://www.drdobbs.com/database/ternary-search-trees/184410528?pgno=1 */
  15 /*   https://www.cs.princeton.edu/~rs/strings/tstdemo.c.                    */
  16 /* ************************************************************************ */
  17
  18 #include <stdlib.h>
  19 #include <stdint.h>
  20 #include <unistd.h>
  21 #include <wchar.h>
  22 #include <string.h>
  23
  24 #include "xmalloc.h"
  25 #include "list.h"
  26 #include "utils.h"
  27 #include "index.h"
  28
  29 /* List of words matching the current search. */
  30 /* """""""""""""""""""""""""""""""""""""""""" */
  31 ll_t *tst_search_list; /* Must be initialized by ll_new() before use. */
  32
  33 /* ======================================= */
  34 /* Ternary search tree insertion function. */
  35 /* ======================================= */
  36 tst_node_t *
  37 tst_insert(tst_node_t *p, wchar_t *w, void *data)
  38 {
  39   if (p == NULL)
  40   {
  41     p            = (tst_node_t *)xmalloc(sizeof(tst_node_t));
  42     p->splitchar = *w;
  43     p->lokid = p->eqkid = p->hikid = NULL;
  44     p->data                        = NULL;
  45   }
  46
  47   if (*w < p->splitchar)
  48     p->lokid = tst_insert(p->lokid, w, data);
  49   else if (*w == p->splitchar)
  50   {
  51     if (*w == L'\0')
  52     {
  53       p->data  = data;
  54       p->eqkid = NULL;
  55     }
  56     else
  57       p->eqkid = tst_insert(p->eqkid, w + 1, data);
  58   }
  59   else
  60     p->hikid = tst_insert(p->hikid, w, data);
  61
  62   return (p);
  63 }
  64
  65 /* ====================================== */
  66 /* Ternary search tree deletion function. */
  67 /* User data area not cleaned.            */
  68 /* ====================================== */
  69 void
  70 tst_cleanup(tst_node_t *p)
  71 {
  72   if (p != NULL)
  73   {
  74     tst_cleanup(p->lokid);
  75     if (p->splitchar != L'\0')
  76       tst_cleanup(p->eqkid);
  77     tst_cleanup(p->hikid);
  78     free(p);
  79   }
  80 }
  81
  82 /* ========================================================== */
  83 /* Recursive traversal of a ternary tree. A callback function */
  84 /* is also called when a complete string is found.            */
  85 /* Returns 1 if the callback function succeed (returned 1) at */
  86 /* least once.                                                */
  87 /* The first_call argument is for initializing the static     */
  88 /* variable.                                                  */
  89 /* ========================================================== */
  90 int
  91 tst_traverse(tst_node_t *p, int (*callback)(void *), int first_call)
  92 {
  93   static int rc;
  94
  95   if (first_call)
  96     rc = 0;
  97
  98   if (p == NULL)
  99     return 0;
 100   tst_traverse(p->lokid, callback, 0);
 101   if (p->splitchar != L'\0')
 102     tst_traverse(p->eqkid, callback, 0);
 103   else
 104     rc += (*callback)(p->data);
 105   tst_traverse(p->hikid, callback, 0);
 106
 107   return !!rc;
 108 }
 109
 110 /* ======================================================================= */
 111 /* Traverses the word tst looking for a wchar and build a list of pointers */
 112 /* containing all the sub-tst potentially leading to words containing the  */
 113 /* next wchar of the search string.                                        */
 114 /* ======================================================================= */
 115 int
 116 tst_substring_traverse(tst_node_t *p,
 117                        int (*callback)(void *),
 118                        int     first_call,
 119                        wchar_t w)
 120 {
 121   static int rc;
 122
 123   if (first_call)
 124     rc = 0;
 125
 126   if (p == NULL)
 127     return 0;
 128
 129   if (p->splitchar == w)
 130   {
 131     ll_node_t *node;
 132     sub_tst_t *sub_tst_data;
 133
 134     node         = tst_search_list->tail;
 135     sub_tst_data = (sub_tst_t *)(node->data);
 136
 137     if (p->eqkid != NULL)
 138       insert_sorted_ptr(&(sub_tst_data->array),
 139                         &(sub_tst_data->size),
 140                         &(sub_tst_data->count),
 141                         p->eqkid);
 142
 143     rc = 1;
 144   }
 145
 146   tst_substring_traverse(p->lokid, callback, 0, w);
 147   if (p->splitchar != L'\0')
 148     tst_substring_traverse(p->eqkid, callback, 0, w);
 149   else if (callback != NULL)
 150     rc += (*callback)(p->data);
 151   tst_substring_traverse(p->hikid, callback, 0, w);
 152
 153   return !!rc;
 154 }
 155
 156 /* ======================================================================== */
 157 /* Traverses the word tst looking for a wchar and build a list of pointers  */
 158 /* containing all the sub-tst nodes potentially leading to words containing */
 159 /* the next wchar os the search string.                                     */
 160 /* ======================================================================== */
 161 int
 162 tst_fuzzy_traverse(tst_node_t *p,
 163                    int (*callback)(void *),
 164                    int     first_call,
 165                    wchar_t w)
 166 {
 167   static int rc;
 168   wchar_t    w1s[2];
 169   wchar_t    w2s[2];
 170
 171   w1s[1] = w2s[1] = L'\0';
 172
 173   if (first_call)
 174     rc = 0;
 175
 176   if (p == NULL)
 177     return 0;
 178
 179   w1s[0] = p->splitchar;
 180   w2s[0] = w;
 181
 182   if (my_wcscasecmp(w1s, w2s) == 0)
 183   {
 184     ll_node_t *node;
 185     sub_tst_t *sub_tst_data;
 186
 187     node         = tst_search_list->tail;
 188     sub_tst_data = (sub_tst_t *)(node->data);
 189
 190     if (p->eqkid != NULL)
 191       insert_sorted_ptr(&(sub_tst_data->array),
 192                         &(sub_tst_data->size),
 193                         &(sub_tst_data->count),
 194                         p->eqkid);
 195
 196     rc += 1;
 197   }
 198
 199   tst_fuzzy_traverse(p->lokid, callback, 0, w);
 200   if (p->splitchar != L'\0')
 201     tst_fuzzy_traverse(p->eqkid, callback, 0, w);
 202   else if (callback != NULL)
 203     rc += (*callback)(p->data);
 204   tst_fuzzy_traverse(p->hikid, callback, 0, w);
 205
 206   return !!rc;
 207 }
 208
 209 /* ======================================================================= */
 210 /* Searches a complete string in a ternary tree starting from a root node. */
 211 /* ======================================================================= */
 212 void *
 213 tst_search(tst_node_t *root, wchar_t *w)
 214 {
 215   tst_node_t *p;
 216
 217   p = root;
 218
 219   while (p)
 220   {
 221     if (*w < p->splitchar)
 222       p = p->lokid;
 223     else if (*w == p->splitchar)
 224     {
 225       if (*w++ == L'\0')
 226         return p->data;
 227       p = p->eqkid;
 228     }
 229     else
 230       p = p->hikid;
 231   }
 232
 233   return NULL;
 234 }
 235
 236 /* ============================================================== */
 237 /* Searches all strings beginning with the same prefix.           */
 238 /* the callback function will be applied to each of these strings */
 239 /* returns NULL if no string matched the prefix.                  */
 240 /* ============================================================== */
 241 void *
 242 tst_prefix_search(tst_node_t *root, wchar_t *w, int (*callback)(void *))
 243 {
 244   tst_node_t *p   = root;
 245   size_t      len = wcslen(w);
 246   size_t      rc;
 247
 248   while (p)
 249   {
 250     if (*w < p->splitchar)
 251       p = p->lokid;
 252     else if (*w == p->splitchar)
 253     {
 254       len--;
 255       if (*w++ == L'\0')
 256         return p->data;
 257       if (len == 0)
 258       {
 259         rc = tst_traverse(p->eqkid, callback, 1);
 260         return (void *)(long)rc;
 261       }
 262       p = p->eqkid;
 263     }
 264     else
 265       p = p->hikid;
 266   }
 267
 268   return NULL;
 269 }
 270
 271 /* ========================================================= */
 272 /* Insertion of an pointer in a already sorted pointer array */
 273 /* without duplications.                                     */
 274 /* ========================================================= */
 275 void
 276 insert_sorted_ptr(tst_node_t ***array_ptr,
 277                   long         *size,
 278                   long         *nb,
 279                   tst_node_t   *ptr)
 280 {
 281   long pos  = *nb;
 282   long left = 0, right = *nb, middle;
 283
 284   if (*nb > 0)
 285   {
 286     /* Bisection search. */
 287     /* """"""""""""""""" */
 288     while (left < right)
 289     {
 290       middle = (left + right) / 2;
 291       if ((intptr_t)((*array_ptr)[middle]) == (intptr_t)ptr)
 292         return; /* Value already in array. */
 293
 294       if ((intptr_t)ptr < (intptr_t)((*array_ptr)[middle]))
 295         right = middle;
 296       else
 297         left = middle + 1;
 298     }
 299     pos = left;
 300   }
 301
 302   if (*nb == *size)
 303   {
 304     *size += 64;
 305     *array_ptr = xrealloc(*array_ptr, *size * sizeof(long));
 306   }
 307
 308   if (*nb > pos)
 309     memmove((*array_ptr) + pos + 1,
 310             (*array_ptr) + pos,
 311             sizeof(ptr) * (*nb - pos));
 312
 313   (*nb)++;
 314
 315   (*array_ptr)[pos] = ptr;
 316 }