lib/hash.h

   1 /* hash - hashing table processing.
   2    Copyright (C) 1998, 1999, 2001 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
  29 # ifndef PARAMS
  30 #  if PROTOTYPES || __STDC__
  31 #   define PARAMS(Args) Args
  32 #  else
  33 #   define PARAMS(Args) ()
  34 #  endif
  35 # endif
  36
  37 typedef unsigned (*Hash_hasher) PARAMS ((const void *, unsigned));
  38 typedef bool (*Hash_comparator) PARAMS ((const void *, const void *));
  39 typedef void (*Hash_data_freer) PARAMS ((void *));
  40 typedef bool (*Hash_processor) PARAMS ((void *, void *));
  41
  42 struct hash_entry
  43   {
  44     void *data;
  45     struct hash_entry *next;
  46   };
  47
  48 struct hash_tuning
  49   {
  50     /* This structure is mainly used for `hash_initialize', see the block
  51        documentation of `hash_reset_tuning' for more complete comments.  */
  52
  53     float shrink_threshold;     /* ratio of used buckets to trigger a shrink */
  54     float shrink_factor;        /* ratio of new smaller size to original size */
  55     float growth_threshold;     /* ratio of used buckets to trigger a growth */
  56     float growth_factor;        /* ratio of new bigger size to original size */
  57     bool is_n_buckets;          /* if CANDIDATE really means table size */
  58   };
  59
  60 typedef struct hash_tuning Hash_tuning;
  61
  62 struct hash_table;
  63
  64 typedef struct hash_table Hash_table;
  65
  66 /* Information and lookup.  */
  67 unsigned hash_get_n_buckets PARAMS ((const Hash_table *));
  68 unsigned hash_get_n_buckets_used PARAMS ((const Hash_table *));
  69 unsigned hash_get_n_entries PARAMS ((const Hash_table *));
  70 unsigned hash_get_max_bucket_length PARAMS ((const Hash_table *));
  71 bool hash_table_ok PARAMS ((const Hash_table *));
  72 void hash_print_statistics PARAMS ((const Hash_table *, FILE *));
  73 void *hash_lookup PARAMS ((const Hash_table *, const void *));
  74
  75 /* Walking.  */
  76 void *hash_get_first PARAMS ((const Hash_table *));
  77 void *hash_get_next PARAMS ((const Hash_table *, const void *));
  78 unsigned hash_get_entries PARAMS ((const Hash_table *, void **, unsigned));
  79 unsigned hash_do_for_each PARAMS ((const Hash_table *, Hash_processor, void *));
  80
  81 /* Allocation and clean-up.  */
  82 unsigned hash_string PARAMS ((const char *, unsigned));
  83 void hash_reset_tuning PARAMS ((Hash_tuning *));
  84 Hash_table *hash_initialize PARAMS ((unsigned, const Hash_tuning *,
  85                                      Hash_hasher, Hash_comparator,
  86                                      Hash_data_freer));
  87 void hash_clear PARAMS ((Hash_table *));
  88 void hash_free PARAMS ((Hash_table *));
  89
  90 /* Insertion and deletion.  */
  91 bool hash_rehash PARAMS ((Hash_table *, unsigned));
  92 void *hash_insert PARAMS ((Hash_table *, const void *));
  93 void *hash_delete PARAMS ((Hash_table *, const void *));
  94
  95 #endif