dict/lookup.c

   1 /* This file is part of the Zebra server.
   2    Copyright (C) 1994-2011 Index Data
   3
   4 Zebra is free software; you can redistribute it and/or modify it under
   5 the terms of the GNU General Public License as published by the Free
   6 Software Foundation; either version 2, or (at your option) any later
   7 version.
   8
   9 Zebra is distributed in the hope that it will be useful, but WITHOUT ANY
  10 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12 for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17
  18 */
  19
  20
  21
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <stdio.h>
  25 #include <assert.h>
  26
  27 #include "dict-p.h"
  28
  29 static char *dict_look(Dict dict, const Dict_char *str, Dict_ptr ptr)
  30 {
  31     int mid, lo, hi;
  32     int cmp;
  33     void *p;
  34     short *indxp;
  35     char *info;
  36
  37     dict_bf_readp(dict->dbf, ptr, &p);
  38     mid = lo = 0;
  39     hi = DICT_nodir(p)-1;
  40     indxp = (short*) ((char*) p+DICT_bsize(p)-sizeof(short));
  41     while (lo <= hi)
  42     {
  43         mid = (lo+hi)/2;
  44         if (indxp[-mid] > 0)
  45         {
  46             /* string (Dict_char *) DICT_EOS terminated */
  47             /* unsigned char        length of information */
  48             /* char *               information */
  49             info = (char*)p + indxp[-mid];
  50             cmp = dict_strcmp((Dict_char*) info, str);
  51             if (!cmp)
  52                 return info+(dict_strlen ((Dict_char*) info)+1)
  53                     *sizeof(Dict_char);
  54         }
  55         else
  56         {
  57             Dict_char dc;
  58             Dict_ptr subptr;
  59
  60             /* Dict_ptr             subptr */
  61             /* Dict_char            sub char */
  62             /* unsigned char        length of information */
  63             /* char *               information */
  64             info = (char*)p - indxp[-mid];
  65             memcpy(&dc, info+sizeof(Dict_ptr), sizeof(Dict_char));
  66             cmp = dc- *str;
  67             if (!cmp)
  68             {
  69                 memcpy(&subptr, info, sizeof(Dict_ptr));
  70                 if (*++str == DICT_EOS)
  71                 {
  72                     if (info[sizeof(Dict_ptr)+sizeof(Dict_char)])
  73                         return info+sizeof(Dict_ptr)+sizeof(Dict_char);
  74                     return NULL;
  75                 }
  76                 else
  77                 {
  78                     if (subptr == 0)
  79                         return NULL;
  80                     ptr = subptr;
  81                     dict_bf_readp(dict->dbf, ptr, &p);
  82                     mid = lo = 0;
  83                     hi = DICT_nodir(p)-1;
  84                     indxp = (short*) ((char*) p+DICT_bsize(p)-sizeof(short));
  85                     continue;
  86                 }
  87             }
  88         }
  89         if (cmp < 0)
  90             lo = mid+1;
  91         else
  92             hi = mid-1;
  93     }
  94     return NULL;
  95 }
  96
  97 char *dict_lookup(Dict dict, const char *p)
  98 {
  99     dict->no_lookup++;
 100     if (!dict->head.root)
 101         return NULL;
 102     return dict_look(dict, (const Dict_char *) p, dict->head.root);
 103 }
 104 /*
 105  * Local variables:
 106  * c-basic-offset: 4
 107  * c-file-style: "Stroustrup"
 108  * indent-tabs-mode: nil
 109  * End:
 110  * vim: shiftwidth=4 tabstop=8 expandtab
 111  */
 112