121 lines
4.6 KiB
C
121 lines
4.6 KiB
C
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/* hash - hashing table processing.
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Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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Written by Jim Meyering <meyering@ascend.com>, 1998.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* A generic hash table package. */
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/* Make sure USE_OBSTACK is defined to 1 if you want the allocator to use
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obstacks instead of malloc, and recompile `hash.c' with same setting. */
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#ifndef PARAMS
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# if PROTOTYPES || __STDC__
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# define PARAMS(Args) Args
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# else
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# define PARAMS(Args) ()
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# endif
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#endif
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typedef unsigned (*Hash_hasher) PARAMS ((const void *, unsigned));
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typedef bool (*Hash_comparator) PARAMS ((const void *, const void *));
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typedef void (*Hash_data_freer) PARAMS ((void *));
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typedef bool (*Hash_processor) PARAMS ((void *, void *));
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struct hash_entry
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{
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void *data;
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struct hash_entry *next;
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};
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struct hash_tuning
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{
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/* This structure is mainly used for `hash_initialize', see the block
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documentation of `hash_reset_tuning' for more complete comments. */
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float shrink_threshold; /* ratio of used buckets to trigger a shrink */
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float shrink_factor; /* ratio of new smaller size to original size */
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float growth_threshold; /* ratio of used buckets to trigger a growth */
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float growth_factor; /* ratio of new bigger size to original size */
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bool is_n_buckets; /* if CANDIDATE really means table size */
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};
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typedef struct hash_tuning Hash_tuning;
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struct hash_table
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{
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/* The array of buckets starts at BUCKET and extends to BUCKET_LIMIT-1,
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for a possibility of N_BUCKETS. Among those, N_BUCKETS_USED buckets
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are not empty, there are N_ENTRIES active entries in the table. */
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struct hash_entry *bucket;
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struct hash_entry *bucket_limit;
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unsigned n_buckets;
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unsigned n_buckets_used;
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unsigned n_entries;
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/* Tuning arguments, kept in a physicaly separate structure. */
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const Hash_tuning *tuning;
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/* Three functions are given to `hash_initialize', see the documentation
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block for this function. In a word, HASHER randomizes a user entry
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into a number up from 0 up to some maximum minus 1; COMPARATOR returns
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true if two user entries compare equally; and DATA_FREER is the cleanup
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function for a user entry. */
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Hash_hasher hasher;
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Hash_comparator comparator;
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Hash_data_freer data_freer;
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/* A linked list of freed struct hash_entry structs. */
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struct hash_entry *free_entry_list;
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#if USE_OBSTACK
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/* Whenever obstacks are used, it is possible to allocate all overflowed
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entries into a single stack, so they all can be freed in a single
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operation. It is not clear if the speedup is worth the trouble. */
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struct obstack entry_stack;
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#endif
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};
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typedef struct hash_table Hash_table;
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/* Information and lookup. */
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unsigned hash_get_n_buckets PARAMS ((const Hash_table *));
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unsigned hash_get_n_buckets_used PARAMS ((const Hash_table *));
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unsigned hash_get_n_entries PARAMS ((const Hash_table *));
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unsigned hash_get_max_bucket_length PARAMS ((const Hash_table *));
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bool hash_table_ok PARAMS ((const Hash_table *));
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void hash_print_statistics PARAMS ((const Hash_table *, FILE *));
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void *hash_lookup PARAMS ((const Hash_table *, const void *));
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/* Walking. */
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void *hash_get_first PARAMS ((const Hash_table *));
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void *hash_get_next PARAMS ((const Hash_table *, const void *));
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unsigned hash_get_entries PARAMS ((const Hash_table *, void **, unsigned));
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unsigned hash_do_for_each PARAMS ((const Hash_table *, Hash_processor, void *));
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/* Allocation and clean-up. */
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unsigned hash_string PARAMS ((const char *, unsigned));
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void hash_reset_tuning PARAMS ((Hash_tuning *));
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Hash_table *hash_initialize PARAMS ((unsigned, const Hash_tuning *,
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Hash_hasher, Hash_comparator,
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Hash_data_freer));
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void hash_clear PARAMS ((Hash_table *));
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void hash_free PARAMS ((Hash_table *));
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/* Insertion and deletion. */
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bool hash_rehash PARAMS ((Hash_table *, unsigned));
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void *hash_insert PARAMS ((Hash_table *, const void *));
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void *hash_delete PARAMS ((Hash_table *, const void *));
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