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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> |
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struct string_to_uint_map; |
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#ifdef __cplusplus |
extern "C" { |
#endif |
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struct hash_table; |
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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); |
|
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/** |
* 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); |
|
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/** |
* 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); |
|
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/** |
* 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); |
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/** |
* 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) |
|
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/** |
* 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); |
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void |
hash_table_call_foreach(struct hash_table *ht, |
void (*callback)(const void *key, |
void *data, |
void *closure), |
void *closure); |
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struct string_to_uint_map * |
string_to_uint_map_ctor(); |
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void |
string_to_uint_map_dtor(struct string_to_uint_map *); |
|
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#ifdef __cplusplus |
} |
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/** |
* 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; |
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value = (unsigned)(v - 1); |
return true; |
} |
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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); |
} |
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private: |
static void delete_key(const void *key, void *data, void *closure) |
{ |
(void) data; |
(void) closure; |
|
free((char *)key); |
} |
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struct hash_table *ht; |
}; |
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#endif /* __cplusplus */ |
#endif /* HASH_TABLE_H */ |