/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef MDS_LIBMDSSERVER_HASH_TABLE_H
#define MDS_LIBMDSSERVER_HASH_TABLE_H
#include <stdlib.h>
/**
* A function that performs a comparison of two objects
*
* @param a The first object
* @param b The second object
* @return Whether the objects are equal
*/
typedef int compare_func(size_t a, size_t b);
/**
* A function that hashes an object or a value
*
* @param value The object or value
* @return The hash of `value`
*/
typedef size_t hash_func(size_t value);
/**
* A function that release an objects resources an frees it
*
* @param obj The object
*/
typedef void free_func(size_t obj);
/**
* Hash table entry
*/
typedef struct hash_entry
{
/**
* A key
*/
size_t key;
/**
* The value associated with the key
*/
size_t value;
/**
* The truncated hash value of the key
*/
size_t hash;
/**
* The next entry in the bucket
*/
struct hash_entry* next;
} hash_entry_t;
/**
* Value lookup table based on hash value, that do not support `0` keys nor `0` values
*/
typedef struct hash_table
{
/**
* The table's capacity, i.e. the number of buckets
*/
size_t capacity;
/**
* Entry buckets
*/
hash_entry_t** buckets;
/**
* When, in the ratio of entries comparied to the capacity, to grow the table
*/
float load_factor;
/**
* When, in the number of entries, to grow the table
*/
size_t threshold;
/**
* The number of entries stored in the table
*/
size_t size;
/**
* Check whether two values are equal
*
* If this function pointer is `NULL`, the identity is used
*
* Be aware, this variable cannot be marshalled
*/
compare_func* value_comparator;
/**
* Check whether two keys are equal
*
* If this function pointer is `NULL`, the identity is used
*
* Be aware, this variable cannot be marshalled
*/
compare_func* key_comparator;
/**
* Calculate the hash of a key
*
* If this function pointer is `NULL`, the identity hash is used
*
* Be aware, this variable cannot be marshalled
*
* @param key The key
* @return The hash of the key
*/
hash_func* hasher;
} hash_table_t;
/**
* Create a hash table
*
* @param this Memory slot in which to store the new hash table
* @param initial_capacity The initial capacity of the table
* @param load_factor The load factor of the table, i.e. when to grow the table
* @return Non-zero on error, `errno` will have been set accordingly
*/
int hash_table_create_fine_tuned(hash_table_t* restrict this, size_t initial_capacity, float load_factor);
/**
* Create a hash table
*
* @param this:hash_table_t* Memory slot in which to store the new hash table
* @param initial_capacity:size_t The initial capacity of the table
* @return :int Non-zero on error, `errno` will have been set accordingly
*/
#define hash_table_create_tuned(this, initial_capacity) \
hash_table_create_fine_tuned(this, initial_capacity, 0.75)
/**
* Create a hash table
*
* @param this:hash_table_t* Memory slot in which to store the new hash table
* @return :int Non-zero on error, `errno` will have been set accordingly
*/
#define hash_table_create(this) \
hash_table_create_tuned(this, 16)
/**
* Release all resources in a hash table, should
* be done even if construction fails
*
* @param this The hash table
* @param keys_freer Function that frees a key, `NULL` if keys should not be freed
* @param values_freer Function that frees a value, `NULL` if value should not be freed
*/
void hash_table_destroy(hash_table_t* restrict this, free_func* key_freer, free_func* value_freer);
/**
* Check whether a value is stored in the table
*
* @param this The hash table
* @param value The value
* @return Whether the value is stored in the table
*/
int hash_table_contains_value(const hash_table_t* restrict this, size_t value) __attribute__((pure));
/**
* Check whether a key is used in the table
*
* @param this The hash table
* @param key The key
* @return Whether the key is used
*/
int hash_table_contains_key(const hash_table_t* restrict this, size_t key) __attribute__((pure));
/**
* Look up a value in the table
*
* @param this The hash table
* @param key The key associated with the value
* @return The value associated with the key, 0 if the key was not used
*/
size_t hash_table_get(const hash_table_t* restrict this, size_t key);
/**
* Add an entry to the table
*
* @param this The hash table
* @param key The key of the entry to add
* @param value The value of the entry to add
* @return The previous value associated with the key, 0 if the key was not used
*/
size_t hash_table_put(hash_table_t* restrict this, size_t key, size_t value);
/**
* Remove an entry in the table
*
* @param this The hash table
* @param key The key of the entry to remove
* @return The previous value associated with the key, 0 if the key was not used
*/
size_t hash_table_remove(hash_table_t* restrict this, size_t key);
/**
* Remove all entries in the table
*
* @param this The hash table
*/
void hash_table_clear(hash_table_t* restrict this);
/**
* Calculate the buffer size need to marshal a hash table
*
* @param this The hash table
* @return The number of bytes to allocate to the output buffer
*/
size_t hash_table_marshal_size(const hash_table_t* restrict this) __attribute__((pure));
/**
* Marshals a hash table
*
* @param this The hash table
* @param data Output buffer for the marshalled data
*/
void hash_table_marshal(const hash_table_t* restrict this, char* restrict data);
/**
* Unmarshals a hash table
*
* @param this Memory slot in which to store the new hash table
* @param data In buffer with the marshalled data
* @return Non-zero one error, errno will be set accordingly.
* Destroy the list on error.
*/
int hash_table_unmarshal(hash_table_t* restrict this, char* restrict data);
#endif
