1/* An expandable hash tables datatype.
2   Copyright (C) 1999, 2000, 2002, 2003, 2004, 2005, 2009, 2010
3   Free Software Foundation, Inc.
4   Contributed by Vladimir Makarov (vmakarov@cygnus.com).
5
6This program is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2 of the License, or
9(at your option) any later version.
10
11This program is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with this program; if not, write to the Free Software
18Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
19
20/* This package implements basic hash table functionality.  It is possible
21   to search for an entry, create an entry and destroy an entry.
22
23   Elements in the table are generic pointers.
24
25   The size of the table is not fixed; if the occupancy of the table
26   grows too high the hash table will be expanded.
27
28   The abstract data implementation is based on generalized Algorithm D
29   from Knuth's book "The art of computer programming".  Hash table is
30   expanded by creation of new hash table and transferring elements from
31   the old table to the new table.  */
32
33#ifndef __HASHTAB_H__
34#define __HASHTAB_H__
35
36#ifdef __cplusplus
37extern "C" {
38#endif /* __cplusplus */
39
40#include "ansidecl.h"
41
42/* The type for a hash code.  */
43typedef unsigned int hashval_t;
44
45/* Callback function pointer types.  */
46
47/* Calculate hash of a table entry.  */
48typedef hashval_t (*htab_hash) (const void *);
49
50/* Compare a table entry with a possible entry.  The entry already in
51   the table always comes first, so the second element can be of a
52   different type (but in this case htab_find and htab_find_slot
53   cannot be used; instead the variants that accept a hash value
54   must be used).  */
55typedef int (*htab_eq) (const void *, const void *);
56
57/* Cleanup function called whenever a live element is removed from
58   the hash table.  */
59typedef void (*htab_del) (void *);
60
61/* Function called by htab_traverse for each live element.  The first
62   arg is the slot of the element (which can be passed to htab_clear_slot
63   if desired), the second arg is the auxiliary pointer handed to
64   htab_traverse.  Return 1 to continue scan, 0 to stop.  */
65typedef int (*htab_trav) (void **, void *);
66
67/* Memory-allocation function, with the same functionality as calloc().
68   Iff it returns NULL, the hash table implementation will pass an error
69   code back to the user, so if your code doesn't handle errors,
70   best if you use xcalloc instead.  */
71typedef void *(*htab_alloc) (size_t, size_t);
72
73/* We also need a free() routine.  */
74typedef void (*htab_free) (void *);
75
76/* Memory allocation and deallocation; variants which take an extra
77   argument.  */
78typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t);
79typedef void (*htab_free_with_arg) (void *, void *);
80
81/* This macro defines reserved value for empty table entry.  */
82
83#define HTAB_EMPTY_ENTRY    ((PTR) 0)
84
85/* This macro defines reserved value for table entry which contained
86   a deleted element. */
87
88#define HTAB_DELETED_ENTRY  ((PTR) 1)
89
90/* Hash tables are of the following type.  The structure
91   (implementation) of this type is not needed for using the hash
92   tables.  All work with hash table should be executed only through
93   functions mentioned below.  The size of this structure is subject to
94   change.  */
95
96struct htab {
97  /* Pointer to hash function.  */
98  htab_hash hash_f;
99
100  /* Pointer to comparison function.  */
101  htab_eq eq_f;
102
103  /* Pointer to cleanup function.  */
104  htab_del del_f;
105
106  /* Table itself.  */
107  void **entries;
108
109  /* Current size (in entries) of the hash table.  */
110  size_t size;
111
112  /* Current number of elements including also deleted elements.  */
113  size_t n_elements;
114
115  /* Current number of deleted elements in the table.  */
116  size_t n_deleted;
117
118  /* The following member is used for debugging. Its value is number
119     of all calls of `htab_find_slot' for the hash table. */
120  unsigned int searches;
121
122  /* The following member is used for debugging.  Its value is number
123     of collisions fixed for time of work with the hash table. */
124  unsigned int collisions;
125
126  /* Pointers to allocate/free functions.  */
127  htab_alloc alloc_f;
128  htab_free free_f;
129
130  /* Alternate allocate/free functions, which take an extra argument.  */
131  void *alloc_arg;
132  htab_alloc_with_arg alloc_with_arg_f;
133  htab_free_with_arg free_with_arg_f;
134
135  /* Current size (in entries) of the hash table, as an index into the
136     table of primes.  */
137  unsigned int size_prime_index;
138};
139
140typedef struct htab *htab_t;
141
142/* An enum saying whether we insert into the hash table or not.  */
143enum insert_option {NO_INSERT, INSERT};
144
145/* The prototypes of the package functions. */
146
147extern htab_t	htab_create_alloc  (size_t, htab_hash,
148                                    htab_eq, htab_del,
149                                    htab_alloc, htab_free);
150
151extern htab_t	htab_create_alloc_ex (size_t, htab_hash,
152                                      htab_eq, htab_del,
153                                      void *, htab_alloc_with_arg,
154                                      htab_free_with_arg);
155
156extern htab_t  htab_create_typed_alloc (size_t, htab_hash, htab_eq, htab_del,
157					htab_alloc, htab_alloc, htab_free);
158
159/* Backward-compatibility functions.  */
160extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del);
161extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
162
163extern void	htab_set_functions_ex (htab_t, htab_hash,
164                                       htab_eq, htab_del,
165                                       void *, htab_alloc_with_arg,
166                                       htab_free_with_arg);
167
168extern void	htab_delete (htab_t);
169extern void	htab_empty (htab_t);
170
171extern void *	htab_find (htab_t, const void *);
172extern void **	htab_find_slot (htab_t, const void *, enum insert_option);
173extern void *	htab_find_with_hash (htab_t, const void *, hashval_t);
174extern void **	htab_find_slot_with_hash (htab_t, const void *,
175					  hashval_t, enum insert_option);
176extern void	htab_clear_slot	(htab_t, void **);
177extern void	htab_remove_elt	(htab_t, void *);
178extern void	htab_remove_elt_with_hash (htab_t, void *, hashval_t);
179
180extern void	htab_traverse (htab_t, htab_trav, void *);
181extern void	htab_traverse_noresize (htab_t, htab_trav, void *);
182
183extern size_t	htab_size (htab_t);
184extern size_t	htab_elements (htab_t);
185extern double	htab_collisions	(htab_t);
186
187/* A hash function for pointers.  */
188extern htab_hash htab_hash_pointer;
189
190/* An equality function for pointers.  */
191extern htab_eq htab_eq_pointer;
192
193/* A hash function for null-terminated strings.  */
194extern hashval_t htab_hash_string (const void *);
195
196/* An iterative hash function for arbitrary data.  */
197extern hashval_t iterative_hash (const void *, size_t, hashval_t);
198/* Shorthand for hashing something with an intrinsic size.  */
199#define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
200
201#ifdef __cplusplus
202}
203#endif /* __cplusplus */
204
205#endif /* __HASHTAB_H */
206