1/* An expandable hash tables datatype.
2   Copyright (C) 1999, 2000, 2002, 2003, 2004 Free Software Foundation, Inc.
3   Contributed by Vladimir Makarov (vmakarov@cygnus.com).
4
5This program is free software; you can redistribute it and/or modify
6it under the terms of the GNU General Public License as published by
7the Free Software Foundation; either version 2 of the License, or
8(at your option) any later version.
9
10This program is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13GNU General Public License for more details.
14
15You should have received a copy of the GNU General Public License
16along with this program; if not, write to the Free Software
17Foundation, 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
36extern "C" {
37#endif /* __cplusplus */
38
39#include "ansidecl.h"
40
41#ifndef GTY
42#define GTY(X)
43#endif
44
45/* The type for a hash code.  */
46typedef unsigned int hashval_t;
47
48/* Callback function pointer types.  */
49
50/* Calculate hash of a table entry.  */
51typedef hashval_t (*htab_hash) (const void *);
52
53/* Compare a table entry with a possible entry.  The entry already in
54   the table always comes first, so the second element can be of a
55   different type (but in this case htab_find and htab_find_slot
56   cannot be used; instead the variants that accept a hash value
57   must be used).  */
58typedef int (*htab_eq) (const void *, const void *);
59
60/* Cleanup function called whenever a live element is removed from
61   the hash table.  */
62typedef void (*htab_del) (void *);
63
64/* Function called by htab_traverse for each live element.  The first
65   arg is the slot of the element (which can be passed to htab_clear_slot
66   if desired), the second arg is the auxiliary pointer handed to
67   htab_traverse.  Return 1 to continue scan, 0 to stop.  */
68typedef int (*htab_trav) (void **, void *);
69
70/* Memory-allocation function, with the same functionality as calloc().
71   Iff it returns NULL, the hash table implementation will pass an error
72   code back to the user, so if your code doesn't handle errors,
73   best if you use xcalloc instead.  */
74typedef void *(*htab_alloc) (size_t, size_t);
75
76/* We also need a free() routine.  */
77typedef void (*htab_free) (void *);
78
79/* Memory allocation and deallocation; variants which take an extra
80   argument.  */
81typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t);
82typedef void (*htab_free_with_arg) (void *, void *);
83
84/* This macro defines reserved value for empty table entry.  */
85
86#define HTAB_EMPTY_ENTRY    ((PTR) 0)
87
88/* This macro defines reserved value for table entry which contained
89   a deleted element. */
90
91#define HTAB_DELETED_ENTRY  ((PTR) 1)
92
93/* Hash tables are of the following type.  The structure
94   (implementation) of this type is not needed for using the hash
95   tables.  All work with hash table should be executed only through
96   functions mentioned below.  The size of this structure is subject to
97   change.  */
98
99struct htab GTY(())
100{
101  /* Pointer to hash function.  */
102  htab_hash hash_f;
103
104  /* Pointer to comparison function.  */
105  htab_eq eq_f;
106
107  /* Pointer to cleanup function.  */
108  htab_del del_f;
109
110  /* Table itself.  */
111  void ** GTY ((use_param, length ("%h.size"))) entries;
112
113  /* Current size (in entries) of the hash table.  */
114  size_t size;
115
116  /* Current number of elements including also deleted elements.  */
117  size_t n_elements;
118
119  /* Current number of deleted elements in the table.  */
120  size_t n_deleted;
121
122  /* The following member is used for debugging. Its value is number
123     of all calls of `htab_find_slot' for the hash table. */
124  unsigned int searches;
125
126  /* The following member is used for debugging.  Its value is number
127     of collisions fixed for time of work with the hash table. */
128  unsigned int collisions;
129
130  /* Pointers to allocate/free functions.  */
131  htab_alloc alloc_f;
132  htab_free free_f;
133
134  /* Alternate allocate/free functions, which take an extra argument.  */
135  void * GTY((skip)) alloc_arg;
136  htab_alloc_with_arg alloc_with_arg_f;
137  htab_free_with_arg free_with_arg_f;
138
139  /* Current size (in entries) of the hash table, as an index into the
140     table of primes.  */
141  unsigned int size_prime_index;
142};
143
144typedef struct htab *htab_t;
145
146/* An enum saying whether we insert into the hash table or not.  */
147enum insert_option {NO_INSERT, INSERT};
148
149/* The prototypes of the package functions. */
150
151extern htab_t	htab_create_alloc  (size_t, htab_hash,
152                                    htab_eq, htab_del,
153                                    htab_alloc, htab_free);
154
155extern htab_t	htab_create_alloc_ex (size_t, htab_hash,
156                                      htab_eq, htab_del,
157                                      void *, htab_alloc_with_arg,
158                                      htab_free_with_arg);
159
160/* Backward-compatibility functions.  */
161extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del);
162extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
163
164extern void	htab_set_functions_ex (htab_t, htab_hash,
165                                       htab_eq, htab_del,
166                                       void *, htab_alloc_with_arg,
167                                       htab_free_with_arg);
168
169extern void	htab_delete (htab_t);
170extern void	htab_empty (htab_t);
171
172extern void *	htab_find (htab_t, const void *);
173extern void **	htab_find_slot (htab_t, const void *, enum insert_option);
174extern void *	htab_find_with_hash (htab_t, const void *, hashval_t);
175extern void **	htab_find_slot_with_hash (htab_t, const void *,
176					  hashval_t, enum insert_option);
177extern void	htab_clear_slot	(htab_t, void **);
178extern void	htab_remove_elt	(htab_t, void *);
179extern void	htab_remove_elt_with_hash (htab_t, void *, hashval_t);
180
181extern void	htab_traverse (htab_t, htab_trav, void *);
182extern void	htab_traverse_noresize (htab_t, htab_trav, void *);
183
184extern size_t	htab_size (htab_t);
185extern size_t	htab_elements (htab_t);
186extern double	htab_collisions	(htab_t);
187
188/* A hash function for pointers.  */
189extern htab_hash htab_hash_pointer;
190
191/* An equality function for pointers.  */
192extern htab_eq htab_eq_pointer;
193
194/* A hash function for null-terminated strings.  */
195extern hashval_t htab_hash_string (const void *);
196
197/* An iterative hash function for arbitrary data.  */
198extern hashval_t iterative_hash (const void *, size_t, hashval_t);
199/* Shorthand for hashing something with an intrinsic size.  */
200#define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
201
202#ifdef __cplusplus
203}
204#endif /* __cplusplus */
205
206#endif /* __HASHTAB_H */
207