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 /* This macro defines reserved value for empty table entry.  */
  85
  86 #define HTAB_EMPTY_ENTRY    ((PTR) 0)
  87
  88 /* This macro defines reserved value for table entry which contained
  89    a deleted element. */
  90
  91 #define HTAB_DELETED_ENTRY  ((PTR) 1)
  92
  93 /* Hash tables are of the following type.  The structure
  94    (implementation) of this type is not needed for using the hash
  95    tables.  All work with hash table should be executed only through
  96    functions mentioned below.  The size of this structure is subject to
  97    change.  */
  98
  99 struct htab GTY(())
 100 {
 101   /* Pointer to hash function.  */
 102   htab_hash hash_f;
 103
 104   /* Pointer to comparison function.  */
 105   htab_eq eq_f;
 106
 107   /* Pointer to cleanup function.  */
 108   htab_del del_f;
 109
 110   /* Table itself.  */
 111   void ** GTY ((use_param, length ("%h.size"))) entries;
 112
 113   /* Current size (in entries) of the hash table.  */
 114   size_t size;
 115
 116   /* Current number of elements including also deleted elements.  */
 117   size_t n_elements;
 118
 119   /* Current number of deleted elements in the table.  */
 120   size_t n_deleted;
 121
 122   /* The following member is used for debugging. Its value is number
 123      of all calls of `htab_find_slot' for the hash table. */
 124   unsigned int searches;
 125
 126   /* The following member is used for debugging.  Its value is number
 127      of collisions fixed for time of work with the hash table. */
 128   unsigned int collisions;
 129
 130   /* Pointers to allocate/free functions.  */
 131   htab_alloc alloc_f;
 132   htab_free free_f;
 133
 134   /* Alternate allocate/free functions, which take an extra argument.  */
 135   void * GTY((skip)) alloc_arg;
 136   htab_alloc_with_arg alloc_with_arg_f;
 137   htab_free_with_arg free_with_arg_f;
 138
 139   /* Current size (in entries) of the hash table, as an index into the
 140      table of primes.  */
 141   unsigned int size_prime_index;
 142 };
 143
 144 typedef struct htab *htab_t;
 145
 146 /* An enum saying whether we insert into the hash table or not.  */
 147 enum insert_option {NO_INSERT, INSERT};
 148
 149 /* The prototypes of the package functions. */
 150
 151 extern htab_t   htab_create_alloc  (size_t, htab_hash,
 152                                     htab_eq, htab_del,
 153                                     htab_alloc, htab_free);
 154
 155 extern htab_t   htab_create_alloc_ex (size_t, htab_hash,
 156                                       htab_eq, htab_del,
 157                                       void *, htab_alloc_with_arg,
 158                                       htab_free_with_arg);
 159
 160 /* Backward-compatibility functions.  */
 161 extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del);
 162 extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
 163
 164 extern void     htab_set_functions_ex (htab_t, htab_hash,
 165                                        htab_eq, htab_del,
 166                                        void *, htab_alloc_with_arg,
 167                                        htab_free_with_arg);
 168
 169 extern void     htab_delete (htab_t);
 170 extern void     htab_empty (htab_t);
 171
 172 extern void *   htab_find (htab_t, const void *);
 173 extern void **  htab_find_slot (htab_t, const void *, enum insert_option);
 174 extern void *   htab_find_with_hash (htab_t, const void *, hashval_t);
 175 extern void **  htab_find_slot_with_hash (htab_t, const void *,
 176                                           hashval_t, enum insert_option);
 177 extern void     htab_clear_slot (htab_t, void **);
 178 extern void     htab_remove_elt (htab_t, void *);
 179 extern void     htab_remove_elt_with_hash (htab_t, void *, hashval_t);
 180
 181 extern void     htab_traverse (htab_t, htab_trav, void *);
 182 extern void     htab_traverse_noresize (htab_t, htab_trav, void *);
 183
 184 extern size_t   htab_size (htab_t);
 185 extern size_t   htab_elements (htab_t);
 186 extern double   htab_collisions (htab_t);
 187
 188 /* A hash function for pointers.  */
 189 extern htab_hash htab_hash_pointer;
 190
 191 /* An equality function for pointers.  */
 192 extern htab_eq htab_eq_pointer;
 193
 194 /* A hash function for null-terminated strings.  */
 195 extern hashval_t htab_hash_string (const void *);
 196
 197 /* An iterative hash function for arbitrary data.  */
 198 extern hashval_t iterative_hash (const void *, size_t, hashval_t);
 199 /* Shorthand for hashing something with an intrinsic size.  */
 200 #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT)
 201
 202 #ifdef __cplusplus
 203 }
 204 #endif /* __cplusplus */
 205
 206 #endif /* __HASHTAB_H */