include/hashtab.h

   1 /* An expandable hash tables datatype.
   2    Copyright (C) 1999, 2000, 2002 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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) PARAMS ((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) PARAMS ((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) PARAMS ((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) PARAMS ((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 PTR (*htab_alloc) PARAMS ((size_t, size_t));
  75
  76 /* We also need a free() routine.  */
  77 typedef void (*htab_free) PARAMS ((PTR));
  78
  79 /* Hash tables are of the following type.  The structure
  80    (implementation) of this type is not needed for using the hash
  81    tables.  All work with hash table should be executed only through
  82    functions mentioned below. */
  83
  84 struct htab GTY(())
  85 {
  86   /* Pointer to hash function.  */
  87   htab_hash hash_f;
  88
  89   /* Pointer to comparison function.  */
  90   htab_eq eq_f;
  91
  92   /* Pointer to cleanup function.  */
  93   htab_del del_f;
  94
  95   /* Table itself.  */
  96   PTR * GTY ((use_param (""), length ("%h.size"))) entries;
  97
  98   /* Current size (in entries) of the hash table */
  99   size_t size;
 100
 101   /* Current number of elements including also deleted elements */
 102   size_t n_elements;
 103
 104   /* Current number of deleted elements in the table */
 105   size_t n_deleted;
 106
 107   /* The following member is used for debugging. Its value is number
 108      of all calls of `htab_find_slot' for the hash table. */
 109   unsigned int searches;
 110
 111   /* The following member is used for debugging.  Its value is number
 112      of collisions fixed for time of work with the hash table. */
 113   unsigned int collisions;
 114
 115   /* Pointers to allocate/free functions.  */
 116   htab_alloc alloc_f;
 117   htab_free free_f;
 118 };
 119
 120 typedef struct htab *htab_t;
 121
 122 /* An enum saying whether we insert into the hash table or not.  */
 123 enum insert_option {NO_INSERT, INSERT};
 124
 125 /* The prototypes of the package functions. */
 126
 127 extern htab_t   htab_create_alloc       PARAMS ((size_t, htab_hash,
 128                                                  htab_eq, htab_del,
 129                                                  htab_alloc, htab_free));
 130
 131 /* Backward-compatibility functions.  */
 132 extern htab_t htab_create PARAMS ((size_t, htab_hash, htab_eq, htab_del));
 133 extern htab_t htab_try_create PARAMS ((size_t, htab_hash, htab_eq, htab_del));
 134
 135 extern void     htab_delete     PARAMS ((htab_t));
 136 extern void     htab_empty      PARAMS ((htab_t));
 137
 138 extern PTR      htab_find       PARAMS ((htab_t, const void *));
 139 extern PTR     *htab_find_slot  PARAMS ((htab_t, const void *,
 140                                          enum insert_option));
 141 extern PTR      htab_find_with_hash       PARAMS ((htab_t, const void *,
 142                                                    hashval_t));
 143 extern PTR     *htab_find_slot_with_hash  PARAMS ((htab_t, const void *,
 144                                                    hashval_t,
 145                                                    enum insert_option));
 146 extern void     htab_clear_slot PARAMS ((htab_t, void **));
 147 extern void     htab_remove_elt PARAMS ((htab_t, void *));
 148
 149 extern void     htab_traverse   PARAMS ((htab_t, htab_trav, void *));
 150
 151 extern size_t   htab_size       PARAMS ((htab_t));
 152 extern size_t   htab_elements   PARAMS ((htab_t));
 153 extern double   htab_collisions PARAMS ((htab_t));
 154
 155 /* A hash function for pointers.  */
 156 extern htab_hash htab_hash_pointer;
 157
 158 /* An equality function for pointers.  */
 159 extern htab_eq htab_eq_pointer;
 160
 161 /* A hash function for null-terminated strings.  */
 162 extern hashval_t htab_hash_string PARAMS ((const PTR));
 163
 164 #ifdef __cplusplus
 165 }
 166 #endif /* __cplusplus */
 167
 168 #endif /* __HASHTAB_H */