1 /* hash - hashing table processing.
2    Copyright (C) 1998-1999, 2001, 2003, 2009-2012 Free Software Foundation,
3    Inc.
4    Written by Jim Meyering <meyering@ascend.com>, 1998.
5 
6    This program is free software: you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by
8    the Free Software Foundation; either version 3 of the License, or
9    (at your option) any later version.
10 
11    This program is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15 
16    You should have received a copy of the GNU General Public License
17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
18 
19 /* A generic hash table package.  */
20 
21 /* Make sure USE_OBSTACK is defined to 1 if you want the allocator to use
22    obstacks instead of malloc, and recompile 'hash.c' with same setting.  */
23 
24 #ifndef HASH_H_
25 # define HASH_H_
26 
27 # include <stdio.h>
28 # include <stdbool.h>
29 
30 /* The __attribute__ feature is available in gcc versions 2.5 and later.
31    The warn_unused_result attribute appeared first in gcc-3.4.0.  */
32 # if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
33 #  define _GL_ATTRIBUTE_WUR __attribute__ ((__warn_unused_result__))
34 # else
35 #  define _GL_ATTRIBUTE_WUR /* empty */
36 # endif
37 
38 # ifndef _GL_ATTRIBUTE_DEPRECATED
39 /* The __attribute__((__deprecated__)) feature
40    is available in gcc versions 3.1 and newer.  */
41 #  if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
42 #   define _GL_ATTRIBUTE_DEPRECATED /* empty */
43 #  else
44 #   define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
45 #  endif
46 # endif
47 
48 typedef size_t (*Hash_hasher) (const void *, size_t);
49 typedef bool (*Hash_comparator) (const void *, const void *);
50 typedef void (*Hash_data_freer) (void *);
51 typedef bool (*Hash_processor) (void *, void *);
52 
53 struct hash_tuning
54   {
55     /* This structure is mainly used for 'hash_initialize', see the block
56        documentation of 'hash_reset_tuning' for more complete comments.  */
57 
58     float shrink_threshold;     /* ratio of used buckets to trigger a shrink */
59     float shrink_factor;        /* ratio of new smaller size to original size */
60     float growth_threshold;     /* ratio of used buckets to trigger a growth */
61     float growth_factor;        /* ratio of new bigger size to original size */
62     bool is_n_buckets;          /* if CANDIDATE really means table size */
63   };
64 
65 typedef struct hash_tuning Hash_tuning;
66 
67 struct hash_table;
68 
69 typedef struct hash_table Hash_table;
70 
71 /* Information and lookup.  */
72 size_t hash_get_n_buckets (const Hash_table *) _GL_ATTRIBUTE_PURE;
73 size_t hash_get_n_buckets_used (const Hash_table *) _GL_ATTRIBUTE_PURE;
74 size_t hash_get_n_entries (const Hash_table *) _GL_ATTRIBUTE_PURE;
75 size_t hash_get_max_bucket_length (const Hash_table *) _GL_ATTRIBUTE_PURE;
76 bool hash_table_ok (const Hash_table *) _GL_ATTRIBUTE_PURE;
77 void hash_print_statistics (const Hash_table *, FILE *);
78 void *hash_lookup (const Hash_table *, const void *);
79 
80 /* Walking.  */
81 void *hash_get_first (const Hash_table *) _GL_ATTRIBUTE_PURE;
82 void *hash_get_next (const Hash_table *, const void *);
83 size_t hash_get_entries (const Hash_table *, void **, size_t);
84 size_t hash_do_for_each (const Hash_table *, Hash_processor, void *);
85 
86 /* Allocation and clean-up.  */
87 size_t hash_string (const char *, size_t) _GL_ATTRIBUTE_PURE;
88 void hash_reset_tuning (Hash_tuning *);
89 Hash_table *hash_initialize (size_t, const Hash_tuning *,
90                              Hash_hasher, Hash_comparator,
91                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
92 void hash_clear (Hash_table *);
93 void hash_free (Hash_table *);
94 
95 /* Insertion and deletion.  */
96 bool hash_rehash (Hash_table *, size_t) _GL_ATTRIBUTE_WUR;
97 void *hash_insert (Hash_table *, const void *) _GL_ATTRIBUTE_WUR;
98 
99 /* Deprecate this interface.  It has been renamed to hash_insert_if_absent.  */
100 int hash_insert0 (Hash_table *table, /* FIXME: remove in 2013 */
101                   const void *entry,
102                   const void **matched_ent) _GL_ATTRIBUTE_DEPRECATED;
103 int hash_insert_if_absent (Hash_table *table, const void *entry,
104                            const void **matched_ent);
105 void *hash_delete (Hash_table *, const void *);
106 
107 #endif
108