include/hashtab.h

   1 /* An expandable hash tables datatype.
   2    Copyright (C) 1999, 2000, 2002, 2003, 2004 Free Software Foundation, Inc.
   3    Contributed by Vladimir Makarov (vmakarov@cygnus.com).
   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 of the License, or
   8 (at your option) 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
  17 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /* This package implements basic hash table functionality.  It is possible
  20    to search for an entry, create an entry and destroy an entry.
  21
  22    Elements in the table are generic pointers.
  23
  24    The size of the table is not fixed; if the occupancy of the table
  25    grows too high the hash table will be expanded.
  26
  27    The abstract data implementation is based on generalized Algorithm D
  28    from Knuth's book "The art of computer programming".  Hash table is
  29    expanded by creation of new hash table and transferring elements from
  30    the old table to the new table.  */
  31
  32 #ifndef __HASHTAB_H__
  33 #define __HASHTAB_H__
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif /* __cplusplus */
  38
  39 #include "ansidecl.h"
  40
  41 #ifndef GTY
  42 #define GTY(X)
  43 #endif
  44
  45 /* The type for a hash code.  */
  46 typedef unsigned int hashval_t;
  47
  48 /* Callback function pointer types.  */
  49
  50 /* Calculate hash of a table entry.  */
  51 typedef hashval_t (*htab_hash) (const void *);
  52
  53 /* Compare a table entry with a possible entry.  The entry already in
  54    the table always comes first, so the second element can be of a
  55    different type (but in this case htab_find and htab_find_slot
  56    cannot be used; instead the variants that accept a hash value
  57    must be used).  */
  58 typedef int (*htab_eq) (const void *, const void *);
  59
  60 /* Cleanup function called whenever a live element is removed from
  61    the hash table.  */
  62 typedef void (*htab_del) (void *);
  63
  64 /* Function called by htab_traverse for each live element.  The first
  65    arg is the slot of the element (which can be passed to htab_clear_slot
  66    if desired), the second arg is the auxiliary pointer handed to
  67    htab_traverse.  Return 1 to continue scan, 0 to stop.  */
  68 typedef int (*htab_trav) (void **, void *);
  69
  70 /* Memory-allocation function, with the same functionality as calloc().
  71    Iff it returns NULL, the hash table implementation will pass an error
  72    code back to the user, so if your code doesn't handle errors,
  73    best if you use xcalloc instead.  */
  74 typedef void *(*htab_alloc) (size_t, size_t);
  75
  76 /* We also need a free() routine.  */
  77 typedef void (*htab_free) (void *);
  78
  79 /* Memory allocation and deallocation; variants which take an extra
  80    argument.  */
  81 typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t);
  82 typedef void (*htab_free_with_arg) (void *, void *);
  83
  84 /* Hash tables are of the following type.  The structure
  85    (implementation) of this type is not needed for using the hash
  86    tables.  All work with hash table should be executed only through
  87    functions mentioned below.  The size of this structure is subject to
  88    change.  */
  89
  90 struct htab GTY(())
  91 {
  92   /* Pointer to hash function.  */
  93   htab_hash hash_f;
  94
  95   /* Pointer to comparison function.  */
  96   htab_eq eq_f;
  97
  98   /* Pointer to cleanup function.  */
  99   htab_del del_f;
 100
 101   /* Table itself.  */
 102   void ** GTY ((use_param, length ("%h.size"))) entries;
 103
 104   /* Current size (in entries) of the hash table.  */
 105   size_t size;
 106
 107   /* Current number of elements including also deleted elements.  */
 108   size_t n_elements;
 109
 110   /* Current number of deleted elements in the table.  */
 111   size_t n_deleted;
 112
 113   /* The following member is used for debugging. Its value is number
 114      of all calls of `htab_find_slot' for the hash table. */
 115   unsigned int searches;
 116
 117   /* The following member is used for debugging.  Its value is number
 118      of collisions fixed for time of work with the hash table. */
 119   unsigned int collisions;
 120
 121   /* Pointers to allocate/free functions.  */
 122   htab_alloc alloc_f;
 123   htab_free free_f;
 124
 125   /* Alternate allocate/free functions, which take an extra argument.  */
 126   void * GTY((skip)) alloc_arg;
 127   htab_alloc_with_arg alloc_with_arg_f;
 128   htab_free_with_arg free_with_arg_f;
 129
 130   /* Current size (in entries) of the hash table, as an index into the
 131      table of primes.  */
 132   unsigned int size_prime_index;
 133 };
 134
 135 typedef struct htab *htab_t;
 136
 137 /* An enum saying whether we insert into the hash table or not.  */
 138 enum insert_option {NO_INSERT, INSERT};
 139
 140 /* The prototypes of the package functions. */
 141
 142 extern htab_t   htab_create_alloc  (size_t, htab_hash,
 143                                     htab_eq, htab_del,
 144                                     htab_alloc, htab_free);
 145
 146 extern htab_t   htab_create_alloc_ex (size_t, htab_hash,
 147                                       htab_eq, htab_del,
 148                                       void *, htab_alloc_with_arg,
 149                                       htab_free_with_arg);
 150
 151 /* Backward-compatibility functions.  */
 152 extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del);
 153 extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
 154
 155 extern void     htab_set_functions_ex (htab_t, htab_hash,
 156                                        htab_eq, htab_del,
 157                                        void *, htab_alloc_with_arg,
 158                                        htab_free_with_arg);
 159
 160 extern void     htab_delete (htab_t);
 161 extern void     htab_empty (htab_t);
 162
 163 extern void *   htab_find (htab_t, const void *);
 164 extern void **  htab_find_slot (htab_t, const void *, enum insert_option);
 165 extern void *   htab_find_with_hash (htab_t, const void *, hashval_t);
 166 extern void **  htab_find_slot_with_hash (htab_t, const void *,
 167                                           hashval_t, enum insert_option);
 168 extern void     htab_clear_slot (htab_t, void **);
 169 extern void     htab_remove_elt (htab_t, void *);
 170 extern void     htab_remove_elt_with_hash (htab_t, void *, hashval_t);
 171
 172 extern void     htab_traverse (htab_t, htab_trav, void *);
 173 extern void     htab_traverse_noresize (htab_t, htab_trav, void *);
 174
 175 extern size_t   htab_size (htab_t);
 176 extern size_t   htab_elements (htab_t);
 177 extern double   htab_collisions (htab_t);
 178
 179 /* A hash function for pointers.  */
 180 extern htab_hash htab_hash_pointer;
 181
 182 /* An equality function for pointers.  */
 183 extern htab_eq htab_eq_pointer;
 184
 185 /* A hash function for null-terminated strings.  */
 186 extern hashval_t htab_hash_string (const void *);
 187
 188 /* An iterative hash function for arbitrary data.  */
 189 extern hashval_t iterative_hash (const void *, size_t, hashval_t);
 190 /* Shorthand for hashing something with an intrinsic size.  */
 191 #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
 192
 193 #ifdef __cplusplus
 194 }
 195 #endif /* __cplusplus */
 196
 197 #endif /* __HASHTAB_H */