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