/* Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */ #ifndef __HASHTABLE_CWC22_H__ #define __HASHTABLE_CWC22_H__ struct hashtable; /* Example of use: * * struct hashtable *h; * struct some_key *k; * struct some_value *v; * * static unsigned int hash_from_key_fn( void *k ); * static int keys_equal_fn ( void *key1, void *key2 ); * * h = create_hashtable(16, hash_from_key_fn, keys_equal_fn); * k = (struct some_key *) malloc(sizeof(struct some_key)); * v = (struct some_value *) malloc(sizeof(struct some_value)); * * (initialise k and v to suitable values) * * if (! hashtable_insert(h,k,v) ) * { exit(-1); } * * if (NULL == (found = hashtable_search(h,k) )) * { printf("not found!"); } * * if (NULL == (found = hashtable_remove(h,k) )) * { printf("Not found\n"); } * */ /* Macros may be used to define type-safe(r) hashtable access functions, with * methods specialized to take known key and value types as parameters. * * Example: * * Insert this at the start of your file: * * DEFINE_HASHTABLE_INSERT(insert_some, struct some_key, struct some_value); * DEFINE_HASHTABLE_SEARCH(search_some, struct some_key, struct some_value); * DEFINE_HASHTABLE_REMOVE(remove_some, struct some_key, struct some_value); * * This defines the functions 'insert_some', 'search_some' and 'remove_some'. * These operate just like hashtable_insert etc., with the same parameters, * but their function signatures have 'struct some_key *' rather than * 'void *', and hence can generate compile time errors if your program is * supplying incorrect data as a key (and similarly for value). * * Note that the hash and key equality functions passed to create_hashtable * still take 'void *' parameters instead of 'some key *'. This shouldn't be * a difficult issue as they're only defined and passed once, and the other * functions will ensure that only valid keys are supplied to them. * * The cost for this checking is increased code size and runtime overhead * - if performance is important, it may be worth switching back to the * unsafe methods once your program has been debugged with the safe methods. * This just requires switching to some simple alternative defines - eg: * #define insert_some hashtable_insert * */ /***************************************************************************** * create_hashtable * @name create_hashtable * @param minsize minimum initial size of hashtable * @param hashfunction function for hashing keys * @param key_eq_fn function for determining key equality * @return newly created hashtable or NULL on failure */ struct hashtable * create_hashtable(unsigned int minsize, unsigned int (*hashfunction) (void*), int (*key_eq_fn) (void*,void*)); /***************************************************************************** * hashtable_insert * @name hashtable_insert * @param h the hashtable to insert into * @param k the key - hashtable claims ownership and will free on removal * @param v the value - does not claim ownership * @return non-zero for successful insertion * * This function will cause the table to expand if the insertion would take * the ratio of entries to table size over the maximum load factor. * * This function does not check for repeated insertions with a duplicate key. * The value returned when using a duplicate key is undefined -- when * the hashtable changes size, the order of retrieval of duplicate key * entries is reversed. * If in doubt, remove before insert. */ int hashtable_insert(struct hashtable *h, void *k, void *v); #define DEFINE_HASHTABLE_INSERT(fnname, keytype, valuetype) \ int fnname (struct hashtable *h, keytype *k, valuetype *v) \ { \ return hashtable_insert(h,k,v); \ } /***************************************************************************** * hashtable_search * @name hashtable_search * @param h the hashtable to search * @param k the key to search for - does not claim ownership * @return the value associated with the key, or NULL if none found */ void * hashtable_search(struct hashtable *h, void *k); #define DEFINE_HASHTABLE_SEARCH(fnname, keytype, valuetype) \ valuetype * fnname (struct hashtable *h, keytype *k) \ { \ return (valuetype *) (hashtable_search(h,k)); \ } /***************************************************************************** * hashtable_remove * @name hashtable_remove * @param h the hashtable to remove the item from * @param k the key to search for - does not claim ownership * @return the value associated with the key, or NULL if none found */ void * /* returns value */ hashtable_remove(struct hashtable *h, void *k); #define DEFINE_HASHTABLE_REMOVE(fnname, keytype, valuetype) \ valuetype * fnname (struct hashtable *h, keytype *k) \ { \ return (valuetype *) (hashtable_remove(h,k)); \ } /***************************************************************************** * hashtable_count * @name hashtable_count * @param h the hashtable * @return the number of items stored in the hashtable */ unsigned int hashtable_count(struct hashtable *h); /***************************************************************************** * hashtable_destroy * @name hashtable_destroy * @param h the hashtable * @param free_values whether to call 'free' on the remaining values */ void hashtable_destroy(struct hashtable *h, int free_values); #endif /* __HASHTABLE_CWC22_H__ */ /* * Copyright (c) 2002, Christopher Clark * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * * Neither the name of the original author; nor the names of any contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */