| 1 | /* An expandable hash tables datatype.
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| 2 | Copyright (C) 1999, 2000 Free Software Foundation, Inc.
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| 3 | Contributed by Vladimir Makarov ([email protected]).
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| 4 |
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| 5 | This program is free software; you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation; either version 2 of the License, or
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| 8 | (at your option) any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program; if not, write to the Free Software
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| 17 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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| 18 |
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| 19 | /* This package implements basic hash table functionality. It is possible
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| 20 | to search for an entry, create an entry and destroy an entry.
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| 21 |
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| 22 | Elements in the table are generic pointers.
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| 23 |
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| 24 | The size of the table is not fixed; if the occupancy of the table
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| 25 | grows too high the hash table will be expanded.
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| 26 |
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| 27 | The abstract data implementation is based on generalized Algorithm D
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| 28 | from Knuth's book "The art of computer programming". Hash table is
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| 29 | expanded by creation of new hash table and transferring elements from
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| 30 | the old table to the new table. */
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| 31 |
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| 32 | #ifndef __HASHTAB_H__
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| 33 | #define __HASHTAB_H__
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| 34 |
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| 35 | #ifdef __cplusplus
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| 36 | extern "C" {
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| 37 | #endif /* __cplusplus */
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| 38 |
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| 39 | #include <ansidecl.h>
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| 40 |
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| 41 | /* The type for a hash code. */
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| 42 | typedef unsigned int hashval_t;
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| 43 |
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| 44 | /* Callback function pointer types. */
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| 45 |
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| 46 | /* Calculate hash of a table entry. */
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| 47 | typedef hashval_t (*htab_hash) PARAMS ((const void *));
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| 48 |
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| 49 | /* Compare a table entry with a possible entry. The entry already in
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| 50 | the table always comes first, so the second element can be of a
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| 51 | different type (but in this case htab_find and htab_find_slot
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| 52 | cannot be used; instead the variants that accept a hash value
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| 53 | must be used). */
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| 54 | typedef int (*htab_eq) PARAMS ((const void *, const void *));
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| 55 |
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| 56 | /* Cleanup function called whenever a live element is removed from
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| 57 | the hash table. */
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| 58 | typedef void (*htab_del) PARAMS ((void *));
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| 59 |
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| 60 | /* Function called by htab_traverse for each live element. The first
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| 61 | arg is the slot of the element (which can be passed to htab_clear_slot
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| 62 | if desired), the second arg is the auxiliary pointer handed to
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| 63 | htab_traverse. Return 1 to continue scan, 0 to stop. */
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| 64 | typedef int (*htab_trav) PARAMS ((void **, void *));
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| 65 |
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| 66 | /* Hash tables are of the following type. The structure
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| 67 | (implementation) of this type is not needed for using the hash
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| 68 | tables. All work with hash table should be executed only through
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| 69 | functions mentioned below. */
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| 70 |
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| 71 | struct htab
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| 72 | {
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| 73 | /* Pointer to hash function. */
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| 74 | htab_hash hash_f;
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| 75 |
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| 76 | /* Pointer to comparison function. */
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| 77 | htab_eq eq_f;
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| 78 |
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| 79 | /* Pointer to cleanup function. */
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| 80 | htab_del del_f;
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| 81 |
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| 82 | /* Table itself. */
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