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[binutils.git] / include / hashtab.h
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1 /* An expandable hash tables datatype.
2 Copyright (C) 1999, 2000 Free Software Foundation, Inc.
3 Contributed by Vladimir Makarov (vmakarov@cygnus.com).
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.
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.
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. */
19 /* This package implements basic hash table functionality. It is possible
20 to search for an entry, create an entry and destroy an entry.
22 Elements in the table are generic pointers.
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.
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. */
32 #ifndef __HASHTAB_H__
33 #define __HASHTAB_H__
35 #ifdef __cplusplus
36 extern "C" {
37 #endif /* __cplusplus */
39 #include <ansidecl.h>
41 /* The type for a hash code. */
42 typedef unsigned int hashval_t;
44 /* Callback function pointer types. */
46 /* Calculate hash of a table entry. */
47 typedef hashval_t (*htab_hash) PARAMS ((const void *));
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) PARAMS ((const void *, const void *));
56 /* Cleanup function called whenever a live element is removed from
57 the hash table. */
58 typedef void (*htab_del) PARAMS ((void *));
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) PARAMS ((void **, void *));
66 /* Hash tables are of the following type. The structure
67 (implementation) of this type is not needed for using the hash
68 tables. All work with hash table should be executed only through
69 functions mentioned below. */
71 struct htab
73 /* Pointer to hash function. */
74 htab_hash hash_f;
76 /* Pointer to comparison function. */
77 htab_eq eq_f;
79 /* Pointer to cleanup function. */
80 htab_del del_f;
82 /* Table itself. */
83 PTR *entries;
85 /* Current size (in entries) of the hash table */
86 size_t size;
88 /* Current number of elements including also deleted elements */
89 size_t n_elements;
91 /* Current number of deleted elements in the table */
92 size_t n_deleted;
94 /* The following member is used for debugging. Its value is number
95 of all calls of `htab_find_slot' for the hash table. */
96 unsigned int searches;
98 /* The following member is used for debugging. Its value is number
99 of collisions fixed for time of work with the hash table. */
100 unsigned int collisions;
102 /* This is non-zero if we are allowed to return NULL for function calls
103 that allocate memory. */
104 int return_allocation_failure;
107 typedef struct htab *htab_t;
109 /* An enum saying whether we insert into the hash table or not. */
110 enum insert_option {NO_INSERT, INSERT};
112 /* The prototypes of the package functions. */
114 extern htab_t htab_create PARAMS ((size_t, htab_hash,
115 htab_eq, htab_del));
117 /* This function is like htab_create, but may return NULL if memory
118 allocation fails, and also signals that htab_find_slot_with_hash and
119 htab_find_slot are allowed to return NULL when inserting. */
120 extern htab_t htab_try_create PARAMS ((size_t, htab_hash,
121 htab_eq, htab_del));
122 extern void htab_delete PARAMS ((htab_t));
123 extern void htab_empty PARAMS ((htab_t));
125 extern PTR htab_find PARAMS ((htab_t, const void *));
126 extern PTR *htab_find_slot PARAMS ((htab_t, const void *,
127 enum insert_option));
128 extern PTR htab_find_with_hash PARAMS ((htab_t, const void *,
129 hashval_t));
130 extern PTR *htab_find_slot_with_hash PARAMS ((htab_t, const void *,
131 hashval_t,
132 enum insert_option));
133 extern void htab_clear_slot PARAMS ((htab_t, void **));
134 extern void htab_remove_elt PARAMS ((htab_t, void *));
136 extern void htab_traverse PARAMS ((htab_t, htab_trav, void *));
138 extern size_t htab_size PARAMS ((htab_t));
139 extern size_t htab_elements PARAMS ((htab_t));
140 extern double htab_collisions PARAMS ((htab_t));
142 /* A hash function for pointers. */
143 extern htab_hash htab_hash_pointer;
145 /* An equality function for pointers. */
146 extern htab_eq htab_eq_pointer;
148 /* A hash function for null-terminated strings. */
149 extern hashval_t htab_hash_string PARAMS ((const PTR));
151 #ifdef __cplusplus
153 #endif /* __cplusplus */
155 #endif /* __HASHTAB_H */