ucx/ucx/map.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2017 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 map.h
 * 
 * Hash map implementation.
 * 
 * This implementation uses murmur hash 2 and separate chaining with linked
 * lists.
 * 
 * @author Mike Becker
 * @author Olaf Wintermann
 */

#ifndef UCX_MAP_H
#define	UCX_MAP_H

#include "ucx.h"
#include "string.h"
#include "allocator.h"
#include <stdio.h>

#ifdef	__cplusplus
extern "C" {
#endif

/**
 * Loop statement for UCX maps.
 * 
 * The <code>key</code> variable is implicitly defined, but the
 * <code>value</code> variable must be already declared as type information
 * cannot be inferred.
 * 
 * @param key the variable name for the key
 * @param value the variable name for the value
 * @param iter a UcxMapIterator
 * @see ucx_map_iterator()
 */
#define UCX_MAP_FOREACH(key,value,iter) \
        for(UcxKey key;ucx_map_iter_next(&iter,&key, (void**)&value);)

/** Type for the UCX map. @see UcxMap */
typedef struct UcxMap          UcxMap;

/** Type for a key of a UcxMap. @see UcxKey */
typedef struct UcxKey          UcxKey;

/** Type for an element of a UcxMap. @see UcxMapElement */
typedef struct UcxMapElement   UcxMapElement;

/** Type for an iterator over a UcxMap. @see UcxMapIterator */
typedef struct UcxMapIterator  UcxMapIterator;

/** Structure for the UCX map. */
struct UcxMap {
    /** An allocator that is used for the map elements. */
    UcxAllocator  *allocator;
    /** The array of map element lists. */
    UcxMapElement **map;
    /** The size of the map is the length of the element list array. */
    size_t        size;
    /** The count of elements currently stored in this map. */
    size_t        count;
};

/** Structure to publicly denote a key of a UcxMap. */
struct UcxKey {
    /** The key data. */
    const void *data;
    /** The length of the key data. */
    size_t     len;
    /** A cache for the hash value of the key data. */
    int        hash;
};

/** Internal structure for a key of a UcxMap. */
struct UcxMapKey {
    /** The key data. */
    void    *data;
    /** The length of the key data. */
    size_t  len;
    /** The hash value of the key data. */
    int     hash;
};

/** Structure for an element of a UcxMap. */
struct UcxMapElement {
    /** The value data. */
    void              *data;
    
    /** A pointer to the next element in the current list. */
    UcxMapElement     *next;
    
    /** The corresponding key. */
    struct UcxMapKey  key;
};

/** Structure for an iterator over a UcxMap. */
struct UcxMapIterator {
    /** The map to iterate over. */
    UcxMap        *map;
    
    /** The current map element. */
    UcxMapElement *cur;
    
    /**
     * The current index of the element list array.
     * <b>Attention: </b> this is <b>NOT</b> the element index! Do <b>NOT</b>
     * manually iterate over the map by increasing this index. Use
     * ucx_map_iter_next().
     * @see UcxMap.map*/
    size_t        index;
};

/**
 * Creates a new hash map with the specified size.
 * @param size the size of the hash map
 * @return a pointer to the new hash map
 */
UcxMap *ucx_map_new(size_t size);

/**
 * Creates a new hash map with the specified size using a UcxAllocator.
 * @param allocator the allocator to use
 * @param size the size of the hash map
 * @return a pointer to the new hash map
 */
UcxMap *ucx_map_new_a(UcxAllocator *allocator, size_t size);

/**
 * Frees a hash map.
 * 
 * <b>Note:</b> the contents are <b>not</b> freed, use ucx_map_free_content()
 * before calling this function to achieve that.
 * 
 * @param map the map to be freed
 * @see ucx_map_free_content()
 */
void ucx_map_free(UcxMap *map);

/**
 * Frees the contents of a hash map.
 * 
 * This is a convenience function that iterates over the map and passes all
 * values to the specified destructor function.
 * 
 * If no destructor is specified (<code>NULL</code>), the free() function of
 * the map's own allocator is used.
 * 
 * You must ensure, that it is valid to pass each value in the map to the same
 * destructor function.
 * 
 * You should free or clear the map afterwards, as the contents will be invalid.
 * 
 * @param map for which the contents shall be freed
 * @param destr optional pointer to a destructor function
 * @see ucx_map_free()
 * @see ucx_map_clear()
 */
void ucx_map_free_content(UcxMap *map, ucx_destructor destr);

/**
 * Clears a hash map.
 * 
 * <b>Note:</b> the contents are <b>not</b> freed, use ucx_map_free_content()
 * before calling this function to achieve that.
 * 
 * @param map the map to be cleared
 * @see ucx_map_free_content()
 */
void ucx_map_clear(UcxMap *map);


/**
 * Copies contents from a map to another map using a copy function.
 * 
 * <b>Note:</b> The destination map does not need to be empty. However, if it
 * contains data with keys that are also present in the source map, the contents
 * are overwritten.
 * 
 * @param from the source map
 * @param to the destination map
 * @param fnc the copy function or <code>NULL</code> if the pointer address
 * shall be copied
 * @param data additional data for the copy function
 * @return 0 on success or a non-zero value on memory allocation errors
 */
int ucx_map_copy(UcxMap *from, UcxMap *to, copy_func fnc, void *data);

/**
 * Clones the map and rehashes if necessary.
 * 
 * <b>Note:</b> In contrast to ucx_map_rehash() the load factor is irrelevant.
 * This function <i>always</i> ensures a new UcxMap.size of at least
 * 2.5*UcxMap.count.
 * 
 * @param map the map to clone
 * @param fnc the copy function to use or <code>NULL</code> if the new and
 * the old map shall share the data pointers
 * @param data additional data for the copy function
 * @return the cloned map
 * @see ucx_map_copy()
 */
UcxMap *ucx_map_clone(UcxMap *map, copy_func fnc, void *data);

/**
 * Increases size of the hash map, if necessary.
 * 
 * The load value is 0.75*UcxMap.size. If the element count exceeds the load
 * value, the map needs to be rehashed. Otherwise no action is performed and
 * this function simply returns 0.
 * 
 * The rehashing process ensures, that the UcxMap.size is at least
 * 2.5*UcxMap.count. So there is enough room for additional elements without
 * the need of another soon rehashing.
 * 
 * You can use this function to dramatically increase access performance.
 * 
 * @param map the map to rehash
 * @return 1, if a memory allocation error occurred, 0 otherwise
 */
int ucx_map_rehash(UcxMap *map);

/**
 * Puts a key/value-pair into the map.
 * 
 * @param map the map
 * @param key the key
 * @param value the value
 * @return 0 on success, non-zero value on failure
 */
int ucx_map_put(UcxMap *map, UcxKey key, void *value);

/**
 * Retrieves a value by using a key.
 * 
 * @param map the map
 * @param key the key
 * @return the value
 */
void* ucx_map_get(UcxMap *map, UcxKey key);

/**
 * Removes a key/value-pair from the map by using the key.
 * 
 * @param map the map
 * @param key the key
 * @return the removed value
 */
void* ucx_map_remove(UcxMap *map, UcxKey key);

/**
 * Shorthand for putting data with a sstr_t key into the map.
 * @param map the map
 * @param key the key
 * @param value the value
 * @return 0 on success, non-zero value on failure
 * @see ucx_map_put()
 */
#define ucx_map_sstr_put(map, key, value) \
    ucx_map_put(map, ucx_key(key.ptr, key.length), (void*)value)

/**
 * Shorthand for putting data with a C string key into the map.
 * @param map the map
 * @param key the key
 * @param value the value
 * @return 0 on success, non-zero value on failure
 * @see ucx_map_put()
 */
#define ucx_map_cstr_put(map, key, value) \
    ucx_map_put(map, ucx_key(key, strlen(key)), (void*)value)

/**
 * Shorthand for putting data with an integer key into the map.
 * @param map the map
 * @param key the key
 * @param value the value
 * @return 0 on success, non-zero value on failure
 * @see ucx_map_put()
 */
#define ucx_map_int_put(map, key, value) \
    ucx_map_put(map, ucx_key(&key, sizeof(key)), (void*)value)

/**
 * Shorthand for getting data from the map with a sstr_t key.
 * @param map the map
 * @param key the key
 * @return the value
 * @see ucx_map_get()
 */
#define ucx_map_sstr_get(map, key) \
    ucx_map_get(map, ucx_key(key.ptr, key.length))

/**
 * Shorthand for getting data from the map with a C string key.
 * @param map the map
 * @param key the key
 * @return the value
 * @see ucx_map_get()
 */
#define ucx_map_cstr_get(map, key) \
    ucx_map_get(map, ucx_key(key, strlen(key)))

/**
 * Shorthand for getting data from the map with an integer key.
 * @param map the map
 * @param key the key
 * @return the value
 * @see ucx_map_get()
 */
#define ucx_map_int_get(map, key) \
    ucx_map_get(map, ucx_key(&key, sizeof(int)))

/**
 * Shorthand for removing data from the map with a sstr_t key.
 * @param map the map
 * @param key the key
 * @return the removed value
 * @see ucx_map_remove()
 */
#define ucx_map_sstr_remove(map, key) \
    ucx_map_remove(map, ucx_key(key.ptr, key.length))

/**
 * Shorthand for removing data from the map with a C string key.
 * @param map the map
 * @param key the key
 * @return the removed value
 * @see ucx_map_remove()
 */
#define ucx_map_cstr_remove(map, key) \
    ucx_map_remove(map, ucx_key(key, strlen(key)))

/**
 * Shorthand for removing data from the map with an integer key.
 * @param map the map
 * @param key the key
 * @return the removed value
 * @see ucx_map_remove()
 */
#define ucx_map_int_remove(map, key) \
    ucx_map_remove(map, ucx_key(&key, sizeof(key)))

/**
 * Creates a UcxKey based on the given data.
 * 
 * This function implicitly computes the hash.
 * 
 * @param data the data for the key
 * @param len the length of the data
 * @return a UcxKey with implicitly computed hash
 * @see ucx_hash()
 */
UcxKey ucx_key(const void *data, size_t len);

/**
 * Computes a murmur hash-2.
 * 
 * @param data the data to hash
 * @param len the length of the data
 * @return the murmur hash-2 of the data
 */
int ucx_hash(const char *data, size_t len);

/**
 * Creates an iterator for a map.
 * 
 * <b>Note:</b> A UcxMapIterator iterates over all elements in all element
 * lists successively. Therefore the order highly depends on the key hashes and
 * may vary under different map sizes. So generally you may <b>NOT</b> rely on
 * the iteration order.
 * 
 * <b>Note:</b> The iterator is <b>NOT</b> initialized. You need to call
 * ucx_map_iter_next() at least once before accessing any information. However,
 * it is not recommended to access the fields of a UcxMapIterator directly.
 * 
 * @param map the map to create the iterator for
 * @return an iterator initialized on the first element of the
 * first element list
 * @see ucx_map_iter_next()
 */
UcxMapIterator ucx_map_iterator(UcxMap *map);

/**
 * Proceeds to the next element of the map (if any).
 * 
 * Subsequent calls on the same iterator proceed to the next element and
 * store the key/value-pair into the memory specified as arguments of this
 * function.
 * 
 * If no further elements are found, this function returns zero and leaves the
 * last found key/value-pair in memory.
 * 
 * @param iterator the iterator to use
 * @param key a pointer to the memory where to store the key
 * @param value a pointer to the memory where to store the value
 * @return 1, if another element was found, 0 if all elements has been processed
 * @see ucx_map_iterator()
 */
int ucx_map_iter_next(UcxMapIterator *iterator, UcxKey *key, void **value);


#ifdef	__cplusplus
}
#endif

#endif	/* UCX_MAP_H */