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1 | /* An expandable hash tables datatype. | |
2 | Copyright (C) 1999-2023 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 | ||
41 | /* The type for a hash code. */ | |
42 | typedef unsigned int hashval_t; | |
43 | ||
44 | /* Callback function pointer types. */ | |
45 | ||
46 | /* Calculate hash of a table entry. */ | |
47 | typedef hashval_t (*htab_hash) (const void *); | |
48 | ||
49 | /* Compare a table entry with a possible entry. The entry already in | |
50 | the table always comes first, so the second element can be of a | |
51 | different type (but in this case htab_find and htab_find_slot | |
52 | cannot be used; instead the variants that accept a hash value | |
53 | must be used). */ | |
54 | typedef int (*htab_eq) (const void *, const void *); | |
55 | ||
56 | /* Cleanup function called whenever a live element is removed from | |
57 | the hash table. */ | |
58 | typedef void (*htab_del) (void *); | |
59 | ||
60 | /* Function called by htab_traverse for each live element. The first | |
61 | arg is the slot of the element (which can be passed to htab_clear_slot | |
62 | if desired), the second arg is the auxiliary pointer handed to | |
63 | htab_traverse. Return 1 to continue scan, 0 to stop. */ | |
64 | typedef int (*htab_trav) (void **, void *); | |
65 | ||
66 | /* Memory-allocation function, with the same functionality as calloc(). | |
67 | Iff it returns NULL, the hash table implementation will pass an error | |
68 | code back to the user, so if your code doesn't handle errors, | |
69 | best if you use xcalloc instead. */ | |
70 | typedef void *(*htab_alloc) (size_t, size_t); | |
71 | ||
72 | /* We also need a free() routine. */ | |
73 | typedef void (*htab_free) (void *); | |
74 | ||
75 | /* Memory allocation and deallocation; variants which take an extra | |
76 | argument. */ | |
77 | typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t); | |
78 | typedef void (*htab_free_with_arg) (void *, void *); | |
79 | ||
80 | /* This macro defines reserved value for empty table entry. */ | |
81 | ||
82 | #define HTAB_EMPTY_ENTRY ((void *) 0) | |
83 | ||
84 | /* This macro defines reserved value for table entry which contained | |
85 | a deleted element. */ | |
86 | ||
87 | #define HTAB_DELETED_ENTRY ((void *) 1) | |
88 | ||
89 | /* Hash tables are of the following type. The structure | |
90 | (implementation) of this type is not needed for using the hash | |
91 | tables. All work with hash table should be executed only through | |
92 | functions mentioned below. The size of this structure is subject to | |
93 | change. */ | |
94 | ||
95 | struct htab { | |
96 | /* Pointer to hash function. */ | |
97 | htab_hash hash_f; | |
98 | ||
99 | /* Pointer to comparison function. */ | |
100 | htab_eq eq_f; | |
101 | ||
102 | /* Pointer to cleanup function. */ | |
103 | htab_del del_f; | |
104 | ||
105 | /* Table itself. */ | |
106 | void **entries; | |
107 | ||
108 | /* Current size (in entries) of the hash table. */ | |
109 | size_t size; | |
110 | ||
111 | /* Current number of elements including also deleted elements. */ | |
112 | size_t n_elements; | |
113 | ||
114 | /* Current number of deleted elements in the table. */ | |
115 | size_t n_deleted; | |
116 | ||
117 | /* The following member is used for debugging. Its value is number | |
118 | of all calls of `htab_find_slot' for the hash table. */ | |
119 | unsigned int searches; | |
120 | ||
121 | /* The following member is used for debugging. Its value is number | |
122 | of collisions fixed for time of work with the hash table. */ | |
123 | unsigned int collisions; | |
124 | ||
125 | /* Pointers to allocate/free functions. */ | |
126 | htab_alloc alloc_f; | |
127 | htab_free free_f; | |
128 | ||
129 | /* Alternate allocate/free functions, which take an extra argument. */ | |
130 | void *alloc_arg; | |
131 | htab_alloc_with_arg alloc_with_arg_f; | |
132 | htab_free_with_arg free_with_arg_f; | |
133 | ||
134 | /* Current size (in entries) of the hash table, as an index into the | |
135 | table of primes. */ | |
136 | unsigned int size_prime_index; | |
137 | }; | |
138 | ||
139 | typedef struct htab *htab_t; | |
140 | ||
141 | /* An enum saying whether we insert into the hash table or not. */ | |
142 | enum insert_option {NO_INSERT, INSERT}; | |
143 | ||
144 | /* The prototypes of the package functions. */ | |
145 | ||
146 | extern htab_t htab_create_alloc (size_t, htab_hash, | |
147 | htab_eq, htab_del, | |
148 | htab_alloc, htab_free); | |
149 | ||
150 | extern htab_t htab_create_alloc_ex (size_t, htab_hash, | |
151 | htab_eq, htab_del, | |
152 | void *, htab_alloc_with_arg, | |
153 | htab_free_with_arg); | |
154 | ||
155 | extern htab_t htab_create_typed_alloc (size_t, htab_hash, htab_eq, htab_del, | |
156 | htab_alloc, htab_alloc, htab_free); | |
157 | ||
158 | /* Backward-compatibility functions. */ | |
159 | extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del); | |
160 | extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del); | |
161 | ||
162 | extern void htab_set_functions_ex (htab_t, htab_hash, | |
163 | htab_eq, htab_del, | |
164 | void *, htab_alloc_with_arg, | |
165 | htab_free_with_arg); | |
166 | ||
167 | extern void htab_delete (htab_t); | |
168 | extern void htab_empty (htab_t); | |
169 | ||
170 | extern void * htab_find (htab_t, const void *); | |
171 | extern void ** htab_find_slot (htab_t, const void *, enum insert_option); | |
172 | extern void * htab_find_with_hash (htab_t, const void *, hashval_t); | |
173 | extern void ** htab_find_slot_with_hash (htab_t, const void *, | |
174 | hashval_t, enum insert_option); | |
175 | extern void htab_clear_slot (htab_t, void **); | |
176 | extern void htab_remove_elt (htab_t, const void *); | |
177 | extern void htab_remove_elt_with_hash (htab_t, const void *, hashval_t); | |
178 | ||
179 | extern void htab_traverse (htab_t, htab_trav, void *); | |
180 | extern void htab_traverse_noresize (htab_t, htab_trav, void *); | |
181 | ||
182 | extern size_t htab_size (htab_t); | |
183 | extern size_t htab_elements (htab_t); | |
184 | extern double htab_collisions (htab_t); | |
185 | ||
186 | /* A hash function for pointers. */ | |
187 | extern htab_hash htab_hash_pointer; | |
188 | ||
189 | /* An equality function for pointers. */ | |
190 | extern htab_eq htab_eq_pointer; | |
191 | ||
192 | /* A hash function for null-terminated strings. */ | |
193 | extern hashval_t htab_hash_string (const void *); | |
194 | ||
195 | /* An equality function for null-terminated strings. */ | |
196 | extern int htab_eq_string (const void *, const void *); | |
197 | ||
198 | /* An iterative hash function for arbitrary data. */ | |
199 | extern hashval_t iterative_hash (const void *, size_t, hashval_t); | |
200 | /* Shorthand for hashing something with an intrinsic size. */ | |
201 | #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT) | |
202 | ||
203 | #ifdef __cplusplus | |
204 | } | |
205 | #endif /* __cplusplus */ | |
206 | ||
207 | #endif /* __HASHTAB_H */ |