Hci Work
[idzebra-moved-to-github.git] / dict / lookup.c
1 /*
2  * Copyright (C) 1994, Index Data I/S 
3  * All rights reserved.
4  * Sebastian Hammer, Adam Dickmeiss
5  *
6  * $Log: lookup.c,v $
7  * Revision 1.7  1996-02-02 13:43:51  adam
8  * The public functions simply use char instead of Dict_char to represent
9  * search strings. Dict_char is used internally only.
10  *
11  * Revision 1.6  1995/12/11  09:04:50  adam
12  * Bug fix: the lookup/scan/lookgrep didn't handle empty dictionary.
13  *
14  * Revision 1.5  1995/09/04  09:09:15  adam
15  * String arg in lookup is const.
16  *
17  * Revision 1.4  1994/10/05  12:16:51  adam
18  * Pagesize is a resource now.
19  *
20  * Revision 1.3  1994/09/26  10:17:25  adam
21  * Minor changes.
22  *
23  * Revision 1.2  1994/09/16  15:39:14  adam
24  * Initial code of lookup - not tested yet.
25  *
26  * Revision 1.1  1994/08/16  16:26:48  adam
27  * Added dict.
28  *
29  */
30
31 #include <stdlib.h>
32 #include <string.h>
33 #include <stdio.h>
34 #include <assert.h>
35
36 #include <dict.h>
37
38 static char *dict_look (Dict dict, const Dict_char *str)
39 {
40     Dict_ptr ptr = 1;
41     int mid, lo, hi;
42     int cmp;
43     void *p;
44     short *indxp;
45     char *info;
46
47     dict_bf_readp (dict->dbf, ptr, &p);
48     mid = lo = 0;
49     hi = DICT_nodir(p)-1;
50     indxp = (short*) ((char*) p+DICT_pagesize(dict)-sizeof(short));    
51     while (lo <= hi)
52     {
53         mid = (lo+hi)/2;
54         if (indxp[-mid] > 0)
55         {
56             /* string (Dict_char *) DICT_EOS terminated */
57             /* unsigned char        length of information */
58             /* char *               information */
59             info = (char*)p + indxp[-mid];
60             cmp = dict_strcmp((Dict_char*) info, str);
61             if (!cmp)
62                 return info+(dict_strlen ((Dict_char*) info)+1)
63                     *sizeof(Dict_char);
64         }
65         else
66         {
67             Dict_char dc;
68             Dict_ptr subptr;
69
70             /* Dict_ptr             subptr */
71             /* Dict_char            sub char */
72             /* unsigned char        length of information */
73             /* char *               information */
74             info = (char*)p - indxp[-mid];
75             memcpy (&dc, info+sizeof(Dict_ptr), sizeof(Dict_char));
76             cmp = dc- *str;
77             if (!cmp)
78             {
79                 memcpy (&subptr, info, sizeof(Dict_ptr));
80                 if (*++str == DICT_EOS)
81                 {
82                     if (info[sizeof(Dict_ptr)+sizeof(Dict_char)])
83                         return info+sizeof(Dict_ptr)+sizeof(Dict_char);
84                     return NULL;
85                 }
86                 else
87                 {
88                     if (subptr == 0)
89                         return NULL;
90                     ptr = subptr;
91                     dict_bf_readp (dict->dbf, ptr, &p);
92                     mid = lo = 0;
93                     hi = DICT_nodir(p)-1;
94                     indxp = (short*) ((char*) p+DICT_pagesize(dict)
95                                       -sizeof(short));
96                     continue;
97                 }
98             }
99         }
100         if (cmp < 0)
101             lo = mid+1;
102         else
103             hi = mid-1;
104     }
105     return NULL;
106 }
107
108 char *dict_lookup (Dict dict, const char *p)
109 {
110     if (dict->head.last <= 1)
111         return NULL;
112     return dict_look (dict, (const Dict_char *) p);
113 }
114
115