1 /* An expandable hash tables datatype. 2 Copyright (C) 1999, 2000, 2002, 2003, 2004, 2005, 2009, 2010 3 Free Software Foundation, Inc. 4 Contributed by Vladimir Makarov (vmakarov@cygnus.com). 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 2 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, write to the Free Software 18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ 19 20 /* This package implements basic hash table functionality. It is possible 21 to search for an entry, create an entry and destroy an entry. 22 23 Elements in the table are generic pointers. 24 25 The size of the table is not fixed; if the occupancy of the table 26 grows too high the hash table will be expanded. 27 28 The abstract data implementation is based on generalized Algorithm D 29 from Knuth's book "The art of computer programming". Hash table is 30 expanded by creation of new hash table and transferring elements from 31 the old table to the new table. */ 32 33 #ifndef __HASHTAB_H__ 34 #define __HASHTAB_H__ 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif /* __cplusplus */ 39 40 #include "ansidecl.h" 41 42 /* The type for a hash code. */ 43 typedef unsigned int hashval_t; 44 45 /* Callback function pointer types. */ 46 47 /* Calculate hash of a table entry. */ 48 typedef hashval_t (*htab_hash) (const void *); 49 50 /* Compare a table entry with a possible entry. The entry already in 51 the table always comes first, so the second element can be of a 52 different type (but in this case htab_find and htab_find_slot 53 cannot be used; instead the variants that accept a hash value 54 must be used). */ 55 typedef int (*htab_eq) (const void *, const void *); 56 57 /* Cleanup function called whenever a live element is removed from 58 the hash table. */ 59 typedef void (*htab_del) (void *); 60 61 /* Function called by htab_traverse for each live element. The first 62 arg is the slot of the element (which can be passed to htab_clear_slot 63 if desired), the second arg is the auxiliary pointer handed to 64 htab_traverse. Return 1 to continue scan, 0 to stop. */ 65 typedef int (*htab_trav) (void **, void *); 66 67 /* Memory-allocation function, with the same functionality as calloc(). 68 Iff it returns NULL, the hash table implementation will pass an error 69 code back to the user, so if your code doesn't handle errors, 70 best if you use xcalloc instead. */ 71 typedef void *(*htab_alloc) (size_t, size_t); 72 73 /* We also need a free() routine. */ 74 typedef void (*htab_free) (void *); 75 76 /* Memory allocation and deallocation; variants which take an extra 77 argument. */ 78 typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t); 79 typedef void (*htab_free_with_arg) (void *, void *); 80 81 /* This macro defines reserved value for empty table entry. */ 82 83 #define HTAB_EMPTY_ENTRY ((PTR) 0) 84 85 /* This macro defines reserved value for table entry which contained 86 a deleted element. */ 87 88 #define HTAB_DELETED_ENTRY ((PTR) 1) 89 90 /* Hash tables are of the following type. The structure 91 (implementation) of this type is not needed for using the hash 92 tables. All work with hash table should be executed only through 93 functions mentioned below. The size of this structure is subject to 94 change. */ 95 96 struct htab { 97 /* Pointer to hash function. */ 98 htab_hash hash_f; 99 100 /* Pointer to comparison function. */ 101 htab_eq eq_f; 102 103 /* Pointer to cleanup function. */ 104 htab_del del_f; 105 106 /* Table itself. */ 107 void **entries; 108 109 /* Current size (in entries) of the hash table. */ 110 size_t size; 111 112 /* Current number of elements including also deleted elements. */ 113 size_t n_elements; 114 115 /* Current number of deleted elements in the table. */ 116 size_t n_deleted; 117 118 /* The following member is used for debugging. Its value is number 119 of all calls of `htab_find_slot' for the hash table. */ 120 unsigned int searches; 121 122 /* The following member is used for debugging. Its value is number 123 of collisions fixed for time of work with the hash table. */ 124 unsigned int collisions; 125 126 /* Pointers to allocate/free functions. */ 127 htab_alloc alloc_f; 128 htab_free free_f; 129 130 /* Alternate allocate/free functions, which take an extra argument. */ 131 void *alloc_arg; 132 htab_alloc_with_arg alloc_with_arg_f; 133 htab_free_with_arg free_with_arg_f; 134 135 /* Current size (in entries) of the hash table, as an index into the 136 table of primes. */ 137 unsigned int size_prime_index; 138 }; 139 140 typedef struct htab *htab_t; 141 142 /* An enum saying whether we insert into the hash table or not. */ 143 enum insert_option {NO_INSERT, INSERT}; 144 145 /* The prototypes of the package functions. */ 146 147 extern htab_t htab_create_alloc (size_t, htab_hash, 148 htab_eq, htab_del, 149 htab_alloc, htab_free); 150 151 extern htab_t htab_create_alloc_ex (size_t, htab_hash, 152 htab_eq, htab_del, 153 void *, htab_alloc_with_arg, 154 htab_free_with_arg); 155 156 extern htab_t htab_create_typed_alloc (size_t, htab_hash, htab_eq, htab_del, 157 htab_alloc, htab_alloc, htab_free); 158 159 /* Backward-compatibility functions. */ 160 extern htab_t htab_create (size_t, htab_hash, htab_eq, htab_del); 161 extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del); 162 163 extern void htab_set_functions_ex (htab_t, htab_hash, 164 htab_eq, htab_del, 165 void *, htab_alloc_with_arg, 166 htab_free_with_arg); 167 168 extern void htab_delete (htab_t); 169 extern void htab_empty (htab_t); 170 171 extern void * htab_find (htab_t, const void *); 172 extern void ** htab_find_slot (htab_t, const void *, enum insert_option); 173 extern void * htab_find_with_hash (htab_t, const void *, hashval_t); 174 extern void ** htab_find_slot_with_hash (htab_t, const void *, 175 hashval_t, enum insert_option); 176 extern void htab_clear_slot (htab_t, void **); 177 extern void htab_remove_elt (htab_t, void *); 178 extern void htab_remove_elt_with_hash (htab_t, void *, hashval_t); 179 180 extern void htab_traverse (htab_t, htab_trav, void *); 181 extern void htab_traverse_noresize (htab_t, htab_trav, void *); 182 183 extern size_t htab_size (htab_t); 184 extern size_t htab_elements (htab_t); 185 extern double htab_collisions (htab_t); 186 187 /* A hash function for pointers. */ 188 extern htab_hash htab_hash_pointer; 189 190 /* An equality function for pointers. */ 191 extern htab_eq htab_eq_pointer; 192 193 /* A hash function for null-terminated strings. */ 194 extern hashval_t htab_hash_string (const void *); 195 196 /* An iterative hash function for arbitrary data. */ 197 extern hashval_t iterative_hash (const void *, size_t, hashval_t); 198 /* Shorthand for hashing something with an intrinsic size. */ 199 #define iterative_hash_object(OB,INIT) iterative_hash (&OB, sizeof (OB), INIT) 200 201 #ifdef __cplusplus 202 } 203 #endif /* __cplusplus */ 204 205 #endif /* __HASHTAB_H */ 206