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., 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
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) PARAMS ((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) PARAMS ((const void *, const void *));
59
60/* Cleanup function called whenever a live element is removed from
61   the hash table.  */
62typedef void (*htab_del) PARAMS ((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) PARAMS ((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 PTR (*htab_alloc) PARAMS ((size_t, size_t));
75
76/* We also need a free() routine.  */
77typedef void (*htab_free) PARAMS ((PTR));
78
79/* Memory allocation and deallocation; variants which take an extra
80   argument.  */
81typedef PTR (*htab_alloc_with_arg) PARAMS ((void *, size_t, size_t));
82typedef void (*htab_free_with_arg) PARAMS ((void *, void *));
83
84/* Hash tables are of the following type.  The structure
85   (implementation) of this type is not needed for using the hash
86   tables.  All work with hash table should be executed only through
87   functions mentioned below.  The size of this structure is subject to
88   change.  */
89
90struct htab GTY(())
91{
92  /* Pointer to hash function.  */
93  htab_hash hash_f;
94
95  /* Pointer to comparison function.  */
96  htab_eq eq_f;
97
98  /* Pointer to cleanup function.  */
99  htab_del del_f;
100
101  /* Table itself.  */
102  PTR * GTY ((use_param, length ("%h.size"))) entries;
103
104  /* Current size (in entries) of the hash table.  */
105  size_t size;
106
107  /* Current number of elements including also deleted elements.  */
108  size_t n_elements;
109
110  /* Current number of deleted elements in the table.  */
111  size_t n_deleted;
112
113  /* The following member is used for debugging. Its value is number
114     of all calls of `htab_find_slot' for the hash table. */
115  unsigned int searches;
116
117  /* The following member is used for debugging.  Its value is number
118     of collisions fixed for time of work with the hash table. */
119  unsigned int collisions;
120
121  /* Pointers to allocate/free functions.  */
122  htab_alloc alloc_f;
123  htab_free free_f;
124
125  /* Alternate allocate/free functions, which take an extra argument.  */
126  PTR GTY((skip)) alloc_arg;
127  htab_alloc_with_arg alloc_with_arg_f;
128  htab_free_with_arg free_with_arg_f;
129
130  /* Current size (in entries) of the hash table, as an index into the
131     table of primes.  */
132  unsigned int size_prime_index;
133};
134
135typedef struct htab *htab_t;
136
137/* An enum saying whether we insert into the hash table or not.  */
138enum insert_option {NO_INSERT, INSERT};
139
140/* The prototypes of the package functions. */
141
142extern htab_t	htab_create_alloc	PARAMS ((size_t, htab_hash,
143						 htab_eq, htab_del,
144						 htab_alloc, htab_free));
145
146extern htab_t	htab_create_alloc_ex	PARAMS ((size_t, htab_hash,
147						    htab_eq, htab_del,
148						    PTR, htab_alloc_with_arg,
149						    htab_free_with_arg));
150
151/* Backward-compatibility functions.  */
152extern htab_t htab_create PARAMS ((size_t, htab_hash, htab_eq, htab_del));
153extern htab_t htab_try_create PARAMS ((size_t, htab_hash, htab_eq, htab_del));
154
155extern void	htab_set_functions_ex	PARAMS ((htab_t, htab_hash,
156						 htab_eq, htab_del,
157						 PTR, htab_alloc_with_arg,
158						 htab_free_with_arg));
159
160extern void	htab_delete	PARAMS ((htab_t));
161extern void	htab_empty	PARAMS ((htab_t));
162
163extern PTR	htab_find	PARAMS ((htab_t, const void *));
164extern PTR     *htab_find_slot	PARAMS ((htab_t, const void *,
165					 enum insert_option));
166extern PTR	htab_find_with_hash	  PARAMS ((htab_t, const void *,
167						   hashval_t));
168extern PTR     *htab_find_slot_with_hash  PARAMS ((htab_t, const void *,
169						   hashval_t,
170						   enum insert_option));
171extern void	htab_clear_slot	PARAMS ((htab_t, void **));
172extern void	htab_remove_elt	PARAMS ((htab_t, void *));
173extern void	htab_remove_elt_with_hash PARAMS ((htab_t, void *, hashval_t));
174
175extern void	htab_traverse	PARAMS ((htab_t, htab_trav, void *));
176extern void	htab_traverse_noresize	PARAMS ((htab_t, htab_trav, void *));
177
178extern size_t	htab_size	PARAMS ((htab_t));
179extern size_t	htab_elements	PARAMS ((htab_t));
180extern double	htab_collisions	PARAMS ((htab_t));
181
182/* A hash function for pointers.  */
183extern htab_hash htab_hash_pointer;
184
185/* An equality function for pointers.  */
186extern htab_eq htab_eq_pointer;
187
188/* A hash function for null-terminated strings.  */
189extern hashval_t htab_hash_string PARAMS ((const PTR));
190
191/* An iterative hash function for arbitrary data.  */
192extern hashval_t iterative_hash PARAMS ((const PTR, size_t, hashval_t));
193/* Shorthand for hashing something with an intrinsic size.  */
194#define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
195
196#ifdef __cplusplus
197}
198#endif /* __cplusplus */
199
200#endif /* __HASHTAB_H */
201