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1 | /* An expandable hash tables datatype. |
2 | Copyright (C) 1999 Free Software Foundation, Inc. | |
3 | Contributed by Vladimir Makarov (vmakarov@cygnus.com). | |
4 | ||
5 | This program is free software; you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
7 | the Free Software Foundation; either version 2 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
16 | along with this program; if not, write to the Free Software | |
17 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
18 | ||
19 | /* This package implements basic hash table functionality. It is possible | |
20 | to search for an entry, create an entry and destroy an entry. | |
21 | ||
22 | Elements in the table are generic pointers. | |
23 | ||
24 | The size of the table is not fixed; if the occupancy of the table | |
25 | grows too high the hash table will be expanded. | |
26 | ||
27 | The abstract data implementation is based on generalized Algorithm D | |
28 | from Knuth's book "The art of computer programming". Hash table is | |
29 | expanded by creation of new hash table and transferring elements from | |
30 | the old table to the new table. */ | |
31 | ||
32 | #ifndef __HASHTAB_H__ | |
33 | #define __HASHTAB_H__ | |
34 | ||
35 | #ifdef __cplusplus | |
36 | extern "C" { | |
37 | #endif /* __cplusplus */ | |
38 | ||
39 | #include <ansidecl.h> | |
40 | ||
5194cf08 | 41 | /* Callback function pointer types. */ |
a6ee63bb | 42 | |
5194cf08 ZW |
43 | /* Calculate hash of a table entry. */ |
44 | typedef unsigned int (*htab_hash) PARAMS ((const void *)); | |
45 | ||
46 | /* Compare a table entry with a possible entry. The entry already in | |
47 | the table always comes first. */ | |
48 | typedef int (*htab_eq) PARAMS ((const void *, const void *)); | |
49 | ||
50 | /* Function called by htab_traverse for each live element. The first | |
51 | arg is the element, the second arg is the auxiliary pointer handed | |
52 | to htab_traverse. Return 1 to continue scan, 0 to stop. */ | |
53 | typedef int (*htab_trav) PARAMS ((void *, void *)); | |
a6ee63bb VM |
54 | |
55 | /* Hash tables are of the following type. The structure | |
56 | (implementation) of this type is not needed for using the hash | |
57 | tables. All work with hash table should be executed only through | |
58 | functions mentioned below. */ | |
59 | ||
5194cf08 | 60 | struct htab |
a6ee63bb | 61 | { |
5194cf08 ZW |
62 | /* Pointer to hash function. */ |
63 | htab_hash hash_f; | |
64 | ||
65 | /* Pointer to comparison function. */ | |
66 | htab_eq eq_f; | |
67 | ||
68 | /* Table itself */ | |
69 | void **entries; | |
70 | ||
a6ee63bb VM |
71 | /* Current size (in entries) of the hash table */ |
72 | size_t size; | |
5194cf08 | 73 | |
a6ee63bb | 74 | /* Current number of elements including also deleted elements */ |
5194cf08 ZW |
75 | size_t n_elements; |
76 | ||
a6ee63bb | 77 | /* Current number of deleted elements in the table */ |
5194cf08 ZW |
78 | size_t n_deleted; |
79 | ||
a6ee63bb | 80 | /* The following member is used for debugging. Its value is number |
5194cf08 ZW |
81 | of all calls of `htab_find_slot' for the hash table. */ |
82 | unsigned int searches; | |
83 | ||
a6ee63bb VM |
84 | /* The following member is used for debugging. Its value is number |
85 | of collisions fixed for time of work with the hash table. */ | |
5194cf08 ZW |
86 | unsigned int collisions; |
87 | }; | |
a6ee63bb | 88 | |
5194cf08 | 89 | typedef struct htab *htab_t; |
a6ee63bb VM |
90 | |
91 | /* The prototypes of the package functions. */ | |
92 | ||
5194cf08 ZW |
93 | extern htab_t htab_create PARAMS ((size_t, htab_hash, htab_eq)); |
94 | extern void htab_delete PARAMS ((htab_t)); | |
95 | extern void htab_empty PARAMS ((htab_t)); | |
a6ee63bb | 96 | |
5194cf08 ZW |
97 | extern void *htab_find PARAMS ((htab_t, const void *)); |
98 | extern void **htab_find_slot PARAMS ((htab_t, const void *, int)); | |
99 | extern void htab_clear_slot PARAMS ((htab_t, void **)); | |
100 | extern void htab_remove_elt PARAMS ((htab_t, void *)); | |
a6ee63bb | 101 | |
5194cf08 | 102 | extern void htab_traverse PARAMS ((htab_t, htab_trav, void *)); |
a6ee63bb | 103 | |
5194cf08 ZW |
104 | extern size_t htab_size PARAMS ((htab_t)); |
105 | extern size_t htab_elements PARAMS ((htab_t)); | |
106 | extern double htab_collisions PARAMS ((htab_t)); | |
a6ee63bb VM |
107 | |
108 | #ifdef __cplusplus | |
109 | } | |
110 | #endif /* __cplusplus */ | |
111 | ||
112 | #endif /* __HASHTAB_H */ |