1 /* An expandable hash tables datatype. 2 Copyright (C) 1999 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 /* Callback function pointer types. */ 42 43 /* Calculate hash of a table entry. */ 44 typedef unsigned int (*htab_hash) PARAMS ((const void *)); 45 46 /* Compare a table entry with a possible entry. The entry already in 47 the table always comes first, so the second element can be of a 48 different type (but in this case htab_find and htab_find_slot 49 cannot be used; instead the variants that accept a hash value 50 must be used). */ 51 typedef int (*htab_eq) PARAMS ((const void *, const void *)); 52 53 /* Cleanup function called whenever a live element is removed from 54 the hash table. */ 55 typedef void (*htab_del) PARAMS ((void *)); 56 57 /* Function called by htab_traverse for each live element. The first 58 arg is the slot of the element (which can be passed to htab_clear_slot 59 if desired), the second arg is the auxiliary pointer handed to 60 htab_traverse. Return 1 to continue scan, 0 to stop. */ 61 typedef int (*htab_trav) PARAMS ((void **, void *)); 62 63 /* Hash tables are of the following type. The structure 64 (implementation) of this type is not needed for using the hash 65 tables. All work with hash table should be executed only through 66 functions mentioned below. */ 67 68 struct htab 69 { 70 /* Pointer to hash function. */ 71 htab_hash hash_f; 72 73 /* Pointer to comparison function. */ 74 htab_eq eq_f; 75 76 /* Pointer to cleanup function. */ 77 htab_del del_f; 78 79 /* Table itself. */ 80 void **entries; 81 82 /* Current size (in entries) of the hash table */ 83 size_t size; 84 85 /* Current number of elements including also deleted elements */ 86 size_t n_elements; 87 88 /* Current number of deleted elements in the table */ 89 size_t n_deleted; 90 91 /* The following member is used for debugging. Its value is number 92 of all calls of `htab_find_slot' for the hash table. */ 93 unsigned int searches; 94 95 /* The following member is used for debugging. Its value is number 96 of collisions fixed for time of work with the hash table. */ 97 unsigned int collisions; 98 }; 99 100 typedef struct htab *htab_t; 101 102 /* The prototypes of the package functions. */ 103 104 extern htab_t htab_create PARAMS ((size_t, htab_hash, 105 htab_eq, htab_del)); 106 extern void htab_delete PARAMS ((htab_t)); 107 extern void htab_empty PARAMS ((htab_t)); 108 109 extern void *htab_find PARAMS ((htab_t, const void *)); 110 extern void **htab_find_slot PARAMS ((htab_t, const void *, int)); 111 extern void *htab_find_with_hash PARAMS ((htab_t, const void *, 112 unsigned int)); 113 extern void **htab_find_slot_with_hash PARAMS ((htab_t, const void *, 114 unsigned int, int)); 115 extern void htab_clear_slot PARAMS ((htab_t, void **)); 116 extern void htab_remove_elt PARAMS ((htab_t, void *)); 117 118 extern void htab_traverse PARAMS ((htab_t, htab_trav, void *)); 119 120 extern size_t htab_size PARAMS ((htab_t)); 121 extern size_t htab_elements PARAMS ((htab_t)); 122 extern double htab_collisions PARAMS ((htab_t)); 123 124 #ifdef __cplusplus 125 } 126 #endif /* __cplusplus */ 127 128 #endif /* __HASHTAB_H */ 129