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| /* |
| * 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 <ian.d.romanick@intel.com> |
| */ |
| |
| #ifndef HASH_TABLE_H |
| #define HASH_TABLE_H |
| |
| #include <string.h> |
| #include <stdbool.h> |
| #include <stdlib.h> |
| #include <stdint.h> |
| #include <limits.h> |
| #include <assert.h> |
| |
| 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 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 |
| } |
| |
| /** |
| * 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); |
| } |
| |
| /** |
| * 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); |
| } |
| |
| struct hash_table *ht; |
| }; |
| |
| #endif /* __cplusplus */ |
| #endif /* HASH_TABLE_H */ |