| 1 | /* An expandable hash tables datatype. |
| 2 | Copyright (C) 1999, 2000 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 | /* The type for a hash code. */ |
| 42 | typedef unsigned int hashval_t; |
| 43 | |
| 44 | /* Callback function pointer types. */ |
| 45 | |
| 46 | /* Calculate hash of a table entry. */ |
| 47 | typedef hashval_t (*htab_hash) PARAMS ((const void *)); |
| 48 | |
| 49 | /* Compare a table entry with a possible entry. The entry already in |
| 50 | the table always comes first, so the second element can be of a |
| 51 | different type (but in this case htab_find and htab_find_slot |
| 52 | cannot be used; instead the variants that accept a hash value |
| 53 | must be used). */ |
| 54 | typedef int (*htab_eq) PARAMS ((const void *, const void *)); |
| 55 | |
| 56 | /* Cleanup function called whenever a live element is removed from |
| 57 | the hash table. */ |
| 58 | typedef void (*htab_del) PARAMS ((void *)); |
| 59 | |
| 60 | /* Function called by htab_traverse for each live element. The first |
| 61 | arg is the slot of the element (which can be passed to htab_clear_slot |
| 62 | if desired), the second arg is the auxiliary pointer handed to |
| 63 | htab_traverse. Return 1 to continue scan, 0 to stop. */ |
| 64 | typedef int (*htab_trav) PARAMS ((void **, void *)); |
| 65 | |
| 66 | /* Hash tables are of the following type. The structure |
| 67 | (implementation) of this type is not needed for using the hash |
| 68 | tables. All work with hash table should be executed only through |
| 69 | functions mentioned below. */ |
| 70 | |
| 71 | struct htab |
| 72 | { |
| 73 | /* Pointer to hash function. */ |
| 74 | htab_hash hash_f; |
| 75 | |
| 76 | /* Pointer to comparison function. */ |
| 77 | htab_eq eq_f; |
| 78 | |
| 79 | /* Pointer to cleanup function. */ |
| 80 | htab_del del_f; |
| 81 | |
| 82 | /* Table itself. */ |
| 83 | PTR *entries; |
| 84 | |
| 85 | /* Current size (in entries) of the hash table */ |
| 86 | size_t size; |
| 87 | |
| 88 | /* Current number of elements including also deleted elements */ |
| 89 | size_t n_elements; |
| 90 | |
| 91 | /* Current number of deleted elements in the table */ |
| 92 | size_t n_deleted; |
| 93 | |
| 94 | /* The following member is used for debugging. Its value is number |
| 95 | of all calls of `htab_find_slot' for the hash table. */ |
| 96 | unsigned int searches; |
| 97 | |
| 98 | /* The following member is used for debugging. Its value is number |
| 99 | of collisions fixed for time of work with the hash table. */ |
| 100 | unsigned int collisions; |
| 101 | |
| 102 | /* This is non-zero if we are allowed to return NULL for function calls |
| 103 | that allocate memory. */ |
| 104 | int return_allocation_failure; |
| 105 | }; |
| 106 | |
| 107 | typedef struct htab *htab_t; |
| 108 | |
| 109 | /* An enum saying whether we insert into the hash table or not. */ |
| 110 | enum insert_option {NO_INSERT, INSERT}; |
| 111 | |
| 112 | /* The prototypes of the package functions. */ |
| 113 | |
| 114 | extern htab_t htab_create PARAMS ((size_t, htab_hash, |
| 115 | htab_eq, htab_del)); |
| 116 | |
| 117 | /* This function is like htab_create, but may return NULL if memory |
| 118 | allocation fails, and also signals that htab_find_slot_with_hash and |
| 119 | htab_find_slot are allowed to return NULL when inserting. */ |
| 120 | extern htab_t htab_try_create PARAMS ((size_t, htab_hash, |
| 121 | htab_eq, htab_del)); |
| 122 | extern void htab_delete PARAMS ((htab_t)); |
| 123 | extern void htab_empty PARAMS ((htab_t)); |
| 124 | |
| 125 | extern PTR htab_find PARAMS ((htab_t, const void *)); |
| 126 | extern PTR *htab_find_slot PARAMS ((htab_t, const void *, |
| 127 | enum insert_option)); |
| 128 | extern PTR htab_find_with_hash PARAMS ((htab_t, const void *, |
| 129 | hashval_t)); |
| 130 | extern PTR *htab_find_slot_with_hash PARAMS ((htab_t, const void *, |
| 131 | hashval_t, |
| 132 | enum insert_option)); |
| 133 | extern void htab_clear_slot PARAMS ((htab_t, void **)); |
| 134 | extern void htab_remove_elt PARAMS ((htab_t, void *)); |
| 135 | |
| 136 | extern void htab_traverse PARAMS ((htab_t, htab_trav, void *)); |
| 137 | |
| 138 | extern size_t htab_size PARAMS ((htab_t)); |
| 139 | extern size_t htab_elements PARAMS ((htab_t)); |
| 140 | extern double htab_collisions PARAMS ((htab_t)); |
| 141 | |
| 142 | /* A hash function for pointers. */ |
| 143 | extern htab_hash htab_hash_pointer; |
| 144 | |
| 145 | /* An equality function for pointers. */ |
| 146 | extern htab_eq htab_eq_pointer; |
| 147 | |
| 148 | /* A hash function for null-terminated strings. */ |
| 149 | extern hashval_t htab_hash_string PARAMS ((const PTR)); |
| 150 | |
| 151 | #ifdef __cplusplus |
| 152 | } |
| 153 | #endif /* __cplusplus */ |
| 154 | |
| 155 | #endif /* __HASHTAB_H */ |