dict/delete.c

   1 /*
   2  * Copyright (C) 1994, Index Data I/S
   3  * All rights reserved.
   4  * Sebastian Hammer, Adam Dickmeiss
   5  *
   6  * $Log: delete.c,v $
   7  * Revision 1.1  1995-12-06 14:52:21  adam
   8  * New function: dict_delete.
   9  *
  10  */
  11
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <stdio.h>
  15 #include <assert.h>
  16
  17 #include <dict.h>
  18
  19 static int dict_del (Dict dict, const Dict_char *str)
  20 {
  21     Dict_ptr ptr = 1;
  22     int mid, lo, hi;
  23     int cmp;
  24     void *p;
  25     short *indxp;
  26     char *info;
  27
  28     dict_bf_readp (dict->dbf, ptr, &p);
  29     mid = lo = 0;
  30     hi = DICT_nodir(p)-1;
  31     indxp = (short*) ((char*) p+DICT_pagesize(dict)-sizeof(short));
  32     while (lo <= hi)
  33     {
  34         mid = (lo+hi)/2;
  35         if (indxp[-mid] > 0)
  36         {
  37             /* string (Dict_char *) DICT_EOS terminated */
  38             /* unsigned char        length of information */
  39             /* char *               information */
  40             info = (char*)p + indxp[-mid];
  41             cmp = dict_strcmp((Dict_char*) info, str);
  42             if (!cmp)
  43             {
  44                 while (mid < hi)
  45                 {
  46                     indxp[-mid] = indxp[-mid-1];
  47                     mid++;
  48                 }
  49                 (DICT_nodir(p))--;
  50                 dict_bf_touch (dict->dbf, ptr);
  51                 return 1;
  52             }
  53         }
  54         else
  55         {
  56             Dict_char dc;
  57             Dict_ptr subptr;
  58
  59             /* Dict_ptr             subptr */
  60             /* Dict_char            sub char */
  61             /* unsigned char        length of information */
  62             /* char *               information */
  63             info = (char*)p - indxp[-mid];
  64             memcpy (&dc, info+sizeof(Dict_ptr), sizeof(Dict_char));
  65             cmp = dc- *str;
  66             if (!cmp)
  67             {
  68                 memcpy (&subptr, info, sizeof(Dict_ptr));
  69                 if (*++str == DICT_EOS)
  70                 {
  71                     if (info[sizeof(Dict_ptr)+sizeof(Dict_char)])
  72                     {
  73                         info[sizeof(Dict_ptr)+sizeof(Dict_char)] = 0;
  74                         dict_bf_touch (dict->dbf, ptr);
  75                         return 1;
  76                     }
  77                     return 0;
  78                 }
  79                 else
  80                 {
  81                     if (subptr == 0)
  82                         return 0;
  83                     ptr = subptr;
  84                     dict_bf_readp (dict->dbf, ptr, &p);
  85                     mid = lo = 0;
  86                     hi = DICT_nodir(p)-1;
  87                     indxp = (short*) ((char*) p+DICT_pagesize(dict)
  88                                       -sizeof(short));
  89                     continue;
  90                 }
  91             }
  92         }
  93         if (cmp < 0)
  94             lo = mid+1;
  95         else
  96             hi = mid-1;
  97     }
  98     return 0;
  99 }
 100
 101 int dict_delete (Dict dict, const Dict_char *p)
 102 {
 103     if (dict->head.last == 1)
 104         return 0;
 105     return dict_del (dict, p);
 106 }