/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 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 HOLDER 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.
*/
/**
* @file hash_map.h
* @brief Hash map implementation.
* @author Mike Becker
* @author Olaf Wintermann
* @copyright 2-Clause BSD License
*/
#ifndef UCX_HASH_MAP_H
#define UCX_HASH_MAP_H
#include "map.h"
#ifdef __cplusplus
extern "C" {
#endif
/** Internal structure for an element of a hash map. */
struct cx_hash_map_element_s;
/**
* Internal structure for a hash map.
*/
struct cx_hash_map_s {
/**
* Base structure for maps.
*/
struct cx_map_s base;
/**
* The buckets of this map, each containing a linked list of elements.
*/
struct cx_hash_map_element_s **buckets;
/**
* The number of buckets.
*/
size_t bucket_count;
};
/**
* Creates a new hash map with the specified number of buckets.
*
* If @p buckets is zero, an implementation defined default will be used.
*
* If @p elem_size is CX_STORE_POINTERS, the created map will be created as if
* cxMapStorePointers() was called immediately after creation.
*
* @note Iterators provided by this hash map implementation provide the remove operation.
* The index value of an iterator is incremented when the iterator advanced without removal.
* In other words, when the iterator is finished, @c index==size .
*
* @param allocator the allocator to use
* (if @c NULL, a default stdlib allocator will be used)
* @param itemsize the size of one element
* @param buckets the initial number of buckets in this hash map
* @return a pointer to the new hash map
*/
cx_attr_nodiscard
cx_attr_malloc
cx_attr_dealloc(cxMapFree, 1)
CxMap *cxHashMapCreate(
const CxAllocator *allocator,
size_t itemsize,
size_t buckets
);
/**
* Creates a new hash map with a default number of buckets.
*
* If @p elem_size is CX_STORE_POINTERS, the created map will be created as if
* cxMapStorePointers() was called immediately after creation.
*
* @note Iterators provided by this hash map implementation provide the remove operation.
* The index value of an iterator is incremented when the iterator advanced without removal.
* In other words, when the iterator is finished, @c index==size .
*
* @param itemsize (@c size_t) the size of one element
* @return (@c CxMap*) a pointer to the new hash map
*/
#define cxHashMapCreateSimple(itemsize) cxHashMapCreate(NULL, itemsize, 0)
/**
* Increases the number of buckets, if necessary.
*
* The load threshold is @c 0.75*buckets. If the element count exceeds the load
* threshold, the map will be rehashed. Otherwise, no action is performed and
* this function simply returns 0.
*
* The rehashing process ensures, that the number of buckets is at least
* 2.5 times the element count. So there is enough room for additional
* elements without the need of another soon rehashing.
*
* You can use this function after filling a map to increase access performance.
*
* @note If the specified map is not a hash map, the behavior is undefined.
*
* @param map the map to rehash
* @retval zero success
* @retval non-zero if a memory allocation error occurred
*/
cx_attr_nonnull
int cxMapRehash(CxMap *map);
#ifdef __cplusplus
} // extern "C"
#endif
#endif // UCX_HASH_MAP_H