/* * Copyright © 2008 Intel Corporation * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. */ /** * \file hash_table.h * \brief Implementation of a generic, opaque hash table data type. * * \author Ian Romanick */ #ifndef HASH_TABLE_H #define HASH_TABLE_H #include #include #include #include #include #include struct string_to_uint_map; #ifdef __cplusplus extern "C" { #endif struct hash_table; typedef unsigned (*hash_func_t)(const void *key); typedef int (*hash_compare_func_t)(const void *key1, const void *key2); /** * Hash table constructor * * Creates a hash table with the specified number of buckets. The supplied * \c hash and \c compare routines are used when adding elements to the table * and when searching for elements in the table. * * \param num_buckets Number of buckets (bins) in the hash table. * \param hash Function used to compute hash value of input keys. * \param compare Function used to compare keys. */ extern struct hash_table *hash_table_ctor(unsigned num_buckets, hash_func_t hash, hash_compare_func_t compare); /** * Release all memory associated with a hash table * * \warning * This function cannot release memory occupied either by keys or data. */ extern void hash_table_dtor(struct hash_table *ht); /** * Flush all entries from a hash table * * \param ht Table to be cleared of its entries. */ extern void hash_table_clear(struct hash_table *ht); /** * Search a hash table for a specific element * * \param ht Table to be searched * \param key Key of the desired element * * \return * The \c data value supplied to \c hash_table_insert when the element with * the matching key was added. If no matching key exists in the table, * \c NULL is returned. */ extern void *hash_table_find(struct hash_table *ht, const void *key); /** * Add an element to a hash table * * \warning * If \c key is already in the hash table, it will be added again. Future * calls to \c hash_table_find and \c hash_table_remove will return or remove, * repsectively, the most recently added instance of \c key. * * \warning * The value passed by \c key is kept in the hash table and is used by later * calls to \c hash_table_find. * * \sa hash_table_replace */ extern void hash_table_insert(struct hash_table *ht, void *data, const void *key); /** * Add an element to a hash table with replacement * * \return * 1 if it did replace the value (in which case the old key is kept), 0 if it * did not replace the value (in which case the new key is kept). * * \warning * If \c key is already in the hash table, \c data will \b replace the most * recently inserted \c data (see the warning in \c hash_table_insert) for * that key. * * \sa hash_table_insert */ extern bool hash_table_replace(struct hash_table *ht, void *data, const void *key); /** * Remove a specific element from a hash table. */ extern void hash_table_remove(struct hash_table *ht, const void *key); /** * Compute hash value of a string * * Computes the hash value of a string using the DJB2 algorithm developed by * Professor Daniel J. Bernstein. It was published on comp.lang.c once upon * a time. I was unable to find the original posting in the archives. * * \param key Pointer to a NUL terminated string to be hashed. * * \sa hash_table_string_compare */ extern unsigned hash_table_string_hash(const void *key); /** * Compare two strings used as keys * * This is just a macro wrapper around \c strcmp. * * \sa hash_table_string_hash */ #define hash_table_string_compare ((hash_compare_func_t) strcmp) /** * Compute hash value of a pointer * * \param key Pointer to be used as a hash key * * \note * The memory pointed to by \c key is \b never accessed. The value of \c key * itself is used as the hash key * * \sa hash_table_pointer_compare */ unsigned hash_table_pointer_hash(const void *key); /** * Compare two pointers used as keys * * \sa hash_table_pointer_hash */ int hash_table_pointer_compare(const void *key1, const void *key2); void hash_table_call_foreach(struct hash_table *ht, void (*callback)(const void *key, void *data, void *closure), void *closure); struct string_to_uint_map * string_to_uint_map_ctor(); void string_to_uint_map_dtor(struct string_to_uint_map *); #ifdef __cplusplus } struct string_map_iterate_wrapper_closure { void (*callback)(const char *key, unsigned value, void *closure); void *closure; }; /** * Map from a string (name) to an unsigned integer value * * \note * Because of the way this class interacts with the \c hash_table * implementation, values of \c UINT_MAX cannot be stored in the map. */ struct string_to_uint_map { public: string_to_uint_map() { this->ht = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare); } ~string_to_uint_map() { hash_table_call_foreach(this->ht, delete_key, NULL); hash_table_dtor(this->ht); } /** * Remove all mappings from this map. */ void clear() { hash_table_call_foreach(this->ht, delete_key, NULL); hash_table_clear(this->ht); } /** * Runs a passed callback for the hash */ void iterate(void (*func)(const char *, unsigned, void *), void *closure) { struct string_map_iterate_wrapper_closure *wrapper; wrapper = (struct string_map_iterate_wrapper_closure *) malloc(sizeof(struct string_map_iterate_wrapper_closure)); if (wrapper == NULL) return; wrapper->callback = func; wrapper->closure = closure; hash_table_call_foreach(this->ht, subtract_one_wrapper, wrapper); free(wrapper); } /** * Get the value associated with a particular key * * \return * If \c key is found in the map, \c true is returned. Otherwise \c false * is returned. * * \note * If \c key is not found in the table, \c value is not modified. */ bool get(unsigned &value, const char *key) { const intptr_t v = (intptr_t) hash_table_find(this->ht, (const void *) key); if (v == 0) return false; value = (unsigned)(v - 1); return true; } void put(unsigned value, const char *key) { /* The low-level hash table structure returns NULL if key is not in the * hash table. However, users of this map might want to store zero as a * valid value in the table. Bias the value by +1 so that a * user-specified zero is stored as 1. This enables ::get to tell the * difference between a user-specified zero (returned as 1 by * hash_table_find) and the key not in the table (returned as 0 by * hash_table_find). * * The net effect is that we can't store UINT_MAX in the table. This is * because UINT_MAX+1 = 0. */ assert(value != UINT_MAX); char *dup_key = strdup(key); bool result = hash_table_replace(this->ht, (void *) (intptr_t) (value + 1), dup_key); if (result) free(dup_key); } private: static void delete_key(const void *key, void *data, void *closure) { (void) data; (void) closure; free((char *)key); } static void subtract_one_wrapper(const void *key, void *data, void *closure) { struct string_map_iterate_wrapper_closure *wrapper = (struct string_map_iterate_wrapper_closure *) closure; unsigned value = (intptr_t) data; value -= 1; wrapper->callback((const char *) key, value, wrapper->closure); } struct hash_table *ht; }; #endif /* __cplusplus */ #endif /* HASH_TABLE_H */