lib/hash.h

   1 /* hash - hashing table processing.
   2    Copyright (C) 1998-1999, 2001, 2003, 2009-2018 Free Software Foundation,
   3    Inc.
   4    Written by Jim Meyering <meyering@ascend.com>, 1998.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  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 /* The __attribute__ feature is available in gcc versions 2.5 and later.
  31    The warn_unused_result attribute appeared first in gcc-3.4.0.  */
  32 # if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
  33 #  define _GL_ATTRIBUTE_WUR __attribute__ ((__warn_unused_result__))
  34 # else
  35 #  define _GL_ATTRIBUTE_WUR /* empty */
  36 # endif
  37
  38 # ifndef _GL_ATTRIBUTE_DEPRECATED
  39 /* The __attribute__((__deprecated__)) feature
  40    is available in gcc versions 3.1 and newer.  */
  41 #  if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
  42 #   define _GL_ATTRIBUTE_DEPRECATED /* empty */
  43 #  else
  44 #   define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
  45 #  endif
  46 # endif
  47
  48 typedef size_t (*Hash_hasher) (const void *, size_t);
  49 typedef bool (*Hash_comparator) (const void *, const void *);
  50 typedef void (*Hash_data_freer) (void *);
  51 typedef bool (*Hash_processor) (void *, void *);
  52
  53 struct hash_tuning
  54   {
  55     /* This structure is mainly used for 'hash_initialize', see the block
  56        documentation of 'hash_reset_tuning' for more complete comments.  */
  57
  58     float shrink_threshold;     /* ratio of used buckets to trigger a shrink */
  59     float shrink_factor;        /* ratio of new smaller size to original size */
  60     float growth_threshold;     /* ratio of used buckets to trigger a growth */
  61     float growth_factor;        /* ratio of new bigger size to original size */
  62     bool is_n_buckets;          /* if CANDIDATE really means table size */
  63   };
  64
  65 typedef struct hash_tuning Hash_tuning;
  66
  67 struct hash_table;
  68
  69 typedef struct hash_table Hash_table;
  70
  71 /* Information and lookup.  */
  72 size_t hash_get_n_buckets (const Hash_table *) _GL_ATTRIBUTE_PURE;
  73 size_t hash_get_n_buckets_used (const Hash_table *) _GL_ATTRIBUTE_PURE;
  74 size_t hash_get_n_entries (const Hash_table *) _GL_ATTRIBUTE_PURE;
  75 size_t hash_get_max_bucket_length (const Hash_table *) _GL_ATTRIBUTE_PURE;
  76 bool hash_table_ok (const Hash_table *) _GL_ATTRIBUTE_PURE;
  77 void hash_print_statistics (const Hash_table *, FILE *);
  78 void *hash_lookup (const Hash_table *, const void *);
  79
  80 /* Walking.  */
  81 void *hash_get_first (const Hash_table *) _GL_ATTRIBUTE_PURE;
  82 void *hash_get_next (const Hash_table *, const void *);
  83 size_t hash_get_entries (const Hash_table *, void **, size_t);
  84 size_t hash_do_for_each (const Hash_table *, Hash_processor, void *);
  85
  86 /* Allocation and clean-up.  */
  87 size_t hash_string (const char *, size_t) _GL_ATTRIBUTE_PURE;
  88 void hash_reset_tuning (Hash_tuning *);
  89 Hash_table *hash_initialize (size_t, const Hash_tuning *,
  90                              Hash_hasher, Hash_comparator,
  91                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
  92 void hash_clear (Hash_table *);
  93 void hash_free (Hash_table *);
  94
  95 /* Insertion and deletion.  */
  96 bool hash_rehash (Hash_table *, size_t) _GL_ATTRIBUTE_WUR;
  97 void *hash_insert (Hash_table *, const void *) _GL_ATTRIBUTE_WUR;
  98
  99 int hash_insert_if_absent (Hash_table *table, const void *entry,
 100                            const void **matched_ent);
 101 void *hash_delete (Hash_table *, const void *);
 102
 103 #endif