104 lines
3.6 KiB
C
104 lines
3.6 KiB
C
/* An expandable hash tables datatype.
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Copyright (C) 1999 Free Software Foundation, Inc.
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Contributed by Vladimir Makarov (vmakarov@cygnus.com).
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* This package implements basic hash table functionality. It is possible
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to search for an entry, create an entry and destroy an entry.
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Elements in the table are generic pointers.
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The size of the table is not fixed; if the occupancy of the table
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grows too high the hash table will be expanded.
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The abstract data implementation is based on generalized Algorithm D
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from Knuth's book "The art of computer programming". Hash table is
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expanded by creation of new hash table and transferring elements from
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the old table to the new table. */
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#ifndef __HASHTAB_H__
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#define __HASHTAB_H__
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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#include <ansidecl.h>
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/* The hash table element is represented by the following type. */
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typedef const void *hash_table_entry_t;
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/* Hash tables are of the following type. The structure
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(implementation) of this type is not needed for using the hash
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tables. All work with hash table should be executed only through
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functions mentioned below. */
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typedef struct
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{
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/* Current size (in entries) of the hash table */
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size_t size;
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/* Current number of elements including also deleted elements */
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size_t number_of_elements;
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/* Current number of deleted elements in the table */
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size_t number_of_deleted_elements;
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/* The following member is used for debugging. Its value is number
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of all calls of `find_hash_table_entry' for the hash table. */
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int searches;
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/* The following member is used for debugging. Its value is number
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of collisions fixed for time of work with the hash table. */
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int collisions;
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/* Pointer to function for evaluation of hash value (any unsigned value).
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This function has one parameter of type hash_table_entry_t. */
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unsigned (*hash_function) PARAMS ((hash_table_entry_t));
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/* Pointer to function for test on equality of hash table elements (two
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parameter of type hash_table_entry_t. */
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int (*eq_function) PARAMS ((hash_table_entry_t, hash_table_entry_t));
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/* Table itself */
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hash_table_entry_t *entries;
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} *hash_table_t;
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/* The prototypes of the package functions. */
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extern hash_table_t create_hash_table
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PARAMS ((size_t, unsigned (*) (hash_table_entry_t),
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int (*) (hash_table_entry_t, hash_table_entry_t)));
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extern void delete_hash_table PARAMS ((hash_table_t));
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extern void empty_hash_table PARAMS ((hash_table_t));
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extern hash_table_entry_t *find_hash_table_entry
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PARAMS ((hash_table_t, hash_table_entry_t, int));
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extern void remove_element_from_hash_table_entry PARAMS ((hash_table_t,
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hash_table_entry_t));
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extern size_t hash_table_size PARAMS ((hash_table_t));
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extern size_t hash_table_elements_number PARAMS ((hash_table_t));
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extern int hash_table_collisions PARAMS ((hash_table_t));
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extern int all_hash_table_collisions ();
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#ifdef __cplusplus
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}
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#endif /* __cplusplus */
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#endif /* __HASHTAB_H */
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