lib/hash.h

   1 /* hash - hashing table processing.
   2    Copyright (C) 1998, 1999, 2001, 2003 Free Software Foundation, Inc.
   3    Written by Jim Meyering <meyering@ascend.com>, 1998.
   4
   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)
   8    any later version.
   9
  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.
  14
  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.  */
  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 typedef size_t (*Hash_hasher) (const void *, size_t);
  31 typedef bool (*Hash_comparator) (const void *, const void *);
  32 typedef void (*Hash_data_freer) (void *);
  33 typedef bool (*Hash_processor) (void *, void *);
  34
  35 struct hash_entry
  36   {
  37     void *data;
  38     struct hash_entry *next;
  39   };
  40
  41 struct hash_tuning
  42   {
  43     /* This structure is mainly used for `hash_initialize', see the block
  44        documentation of `hash_reset_tuning' for more complete comments.  */
  45
  46     float shrink_threshold;     /* ratio of used buckets to trigger a shrink */
  47     float shrink_factor;        /* ratio of new smaller size to original size */
  48     float growth_threshold;     /* ratio of used buckets to trigger a growth */
  49     float growth_factor;        /* ratio of new bigger size to original size */
  50     bool is_n_buckets;          /* if CANDIDATE really means table size */
  51   };
  52
  53 typedef struct hash_tuning Hash_tuning;
  54
  55 struct hash_table;
  56
  57 typedef struct hash_table Hash_table;
  58
  59 /* Information and lookup.  */
  60 size_t hash_get_n_buckets (const Hash_table *);
  61 size_t hash_get_n_buckets_used (const Hash_table *);
  62 size_t hash_get_n_entries (const Hash_table *);
  63 size_t hash_get_max_bucket_length (const Hash_table *);
  64 bool hash_table_ok (const Hash_table *);
  65 void hash_print_statistics (const Hash_table *, FILE *);
  66 void *hash_lookup (const Hash_table *, const void *);
  67
  68 /* Walking.  */
  69 void *hash_get_first (const Hash_table *);
  70 void *hash_get_next (const Hash_table *, const void *);
  71 size_t hash_get_entries (const Hash_table *, void **, size_t);
  72 size_t hash_do_for_each (const Hash_table *, Hash_processor, void *);
  73
  74 /* Allocation and clean-up.  */
  75 size_t hash_string (const char *, size_t);
  76 void hash_reset_tuning (Hash_tuning *);
  77 Hash_table *hash_initialize (size_t, const Hash_tuning *,
  78                              Hash_hasher, Hash_comparator,
  79                              Hash_data_freer);
  80 void hash_clear (Hash_table *);
  81 void hash_free (Hash_table *);
  82
  83 /* Insertion and deletion.  */
  84 bool hash_rehash (Hash_table *, size_t);
  85 void *hash_insert (Hash_table *, const void *);
  86 void *hash_delete (Hash_table *, const void *);
  87
  88 #endif