1 /* hash - hashing table processing.
2 Copyright (C) 1998, 1999, 2001 Free Software Foundation, Inc.
3 Written by Jim Meyering <meyering@ascend.com>, 1998.
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, or (at your option)
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 Foundation,
17 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
19 /* A generic hash table package. */
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. */
28 # if PROTOTYPES || __STDC__
29 # define PARAMS(Args) Args
31 # define PARAMS(Args) ()
35 typedef unsigned (*Hash_hasher) PARAMS ((const void *, unsigned));
36 typedef bool (*Hash_comparator) PARAMS ((const void *, const void *));
37 typedef void (*Hash_data_freer) PARAMS ((void *));
38 typedef bool (*Hash_processor) PARAMS ((void *, void *));
43 struct hash_entry *next;
48 /* This structure is mainly used for `hash_initialize', see the block
49 documentation of `hash_reset_tuning' for more complete comments. */
51 float shrink_threshold; /* ratio of used buckets to trigger a shrink */
52 float shrink_factor; /* ratio of new smaller size to original size */
53 float growth_threshold; /* ratio of used buckets to trigger a growth */
54 float growth_factor; /* ratio of new bigger size to original size */
55 bool is_n_buckets; /* if CANDIDATE really means table size */
58 typedef struct hash_tuning Hash_tuning;
62 /* The array of buckets starts at BUCKET and extends to BUCKET_LIMIT-1,
63 for a possibility of N_BUCKETS. Among those, N_BUCKETS_USED buckets
64 are not empty, there are N_ENTRIES active entries in the table. */
65 struct hash_entry *bucket;
66 struct hash_entry *bucket_limit;
68 unsigned n_buckets_used;
71 /* Tuning arguments, kept in a physicaly separate structure. */
72 const Hash_tuning *tuning;
74 /* Three functions are given to `hash_initialize', see the documentation
75 block for this function. In a word, HASHER randomizes a user entry
76 into a number up from 0 up to some maximum minus 1; COMPARATOR returns
77 true if two user entries compare equally; and DATA_FREER is the cleanup
78 function for a user entry. */
80 Hash_comparator comparator;
81 Hash_data_freer data_freer;
83 /* A linked list of freed struct hash_entry structs. */
84 struct hash_entry *free_entry_list;
87 /* Whenever obstacks are used, it is possible to allocate all overflowed
88 entries into a single stack, so they all can be freed in a single
89 operation. It is not clear if the speedup is worth the trouble. */
90 struct obstack entry_stack;
94 typedef struct hash_table Hash_table;
96 /* Information and lookup. */
97 unsigned hash_get_n_buckets PARAMS ((const Hash_table *));
98 unsigned hash_get_n_buckets_used PARAMS ((const Hash_table *));
99 unsigned hash_get_n_entries PARAMS ((const Hash_table *));
100 unsigned hash_get_max_bucket_length PARAMS ((const Hash_table *));
101 bool hash_table_ok PARAMS ((const Hash_table *));
102 void hash_print_statistics PARAMS ((const Hash_table *, FILE *));
103 void *hash_lookup PARAMS ((const Hash_table *, const void *));
106 void *hash_get_first PARAMS ((const Hash_table *));
107 void *hash_get_next PARAMS ((const Hash_table *, const void *));
108 unsigned hash_get_entries PARAMS ((const Hash_table *, void **, unsigned));
109 unsigned hash_do_for_each PARAMS ((const Hash_table *, Hash_processor, void *));
111 /* Allocation and clean-up. */
112 unsigned hash_string PARAMS ((const char *, unsigned));
113 void hash_reset_tuning PARAMS ((Hash_tuning *));
114 Hash_table *hash_initialize PARAMS ((unsigned, const Hash_tuning *,
115 Hash_hasher, Hash_comparator,
117 void hash_clear PARAMS ((Hash_table *));
118 void hash_free PARAMS ((Hash_table *));
120 /* Insertion and deletion. */
121 bool hash_rehash PARAMS ((Hash_table *, unsigned));
122 void *hash_insert PARAMS ((Hash_table *, const void *));
123 void *hash_delete PARAMS ((Hash_table *, const void *));