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#ifndef GEHASHMAP_H
#define GEHASHMAP_H
#include <stdbool.h>
#include <stdlib.h>
/* GEHASHMAP_INITIAL_SIZE is the initial capacity in items that a newly created
* hashmap can hold. GEHASHMAP_LOAD_FACTOR is the % of the hashmap that can be
* filled before we resize it to hold more items.
*/
#define GEHASHMAP_INITIAL_SIZE 16
#define GEHASHMAP_LOAD_FACTOR 0.75
#define GEHASHMAP_API(k, v, n) \
struct n##_entry { \
k key; \
v val; \
struct n##_entry *next; \
}; \
\
typedef struct { \
size_t size, \
capacity; \
struct n##_entry **entries; \
} n##_t; \
\
void n##_free(n##_t *); \
bool n##_get(n##_t *, k, v *); \
bool n##_has(n##_t *, k); \
int n##_new(n##_t *); \
int n##_set(n##_t *, k, v); \
int n##_remove(n##_t *, k); \
int n##_resize(n##_t *, size_t); \
bool n##_key_iseq(k, k); \
void n##_key_free(k); \
size_t n##_key_hash(k);
#define GEHASHMAP_IMPL(k, v, n) \
/* Function to initialize a new hashmap. Allocation of the hashmap is
* left up to the library user. On error -1 is returned, otherwise 0 is
* returned.
*/ \
int \
n##_new(n##_t *map) \
{ \
*map = (n##_t) { \
.size = 0, \
.capacity = GEHASHMAP_INITIAL_SIZE, \
.entries = calloc(GEHASHMAP_INITIAL_SIZE, \
sizeof(struct n##_entry *)) \
}; \
return map->entries == NULL ? -1 : 0; \
} \
\
/* Function to destroy a hashmap */ \
void \
n##_free(n##_t *map) \
{ \
for (size_t i = 0; i < map->capacity; i++) { \
struct n##_entry *entry = map->entries[i]; \
while (entry != NULL) { \
struct n##_entry *next = entry->next; \
n##_key_free(entry->key); \
free(entry); \
entry = next; \
} \
} \
free(map->entries); \
} \
\
/* Function to resize a hashmap. This function should not really be
* touched by the library user basically ever. On error -1 is returned,
* otherwise 0 is returned.
*/ \
int \
n##_resize(n##_t *map, size_t new_capacity) \
{ \
struct n##_entry **new_entries = \
calloc(new_capacity, sizeof(struct n##_entry *)); \
if (new_entries == NULL) \
return -1; \
\
for (size_t i = 0; i < map->capacity; i++) { \
struct n##_entry *entry = map->entries[i]; \
while (entry != NULL) { \
struct n##_entry *next = entry->next; \
size_t hash = n##_key_hash(entry->key) \
% new_capacity; \
entry->next = new_entries[hash]; \
new_entries[hash] = entry; \
entry = next; \
} \
} \
\
free(map->entries); \
map->entries = new_entries; \
map->capacity = new_capacity; \
\
return 0; \
} \
\
/* Function to put a key/value pair into a hashmap. The key is put into
* the hashmap as is, so the user may need to allocate the key
* themselves if a stack allocated key is not appropriate. On error
* -1 is returned, otherwise 0 is returned.
*/ \
int \
n##_set(n##_t *map, k key, v val) \
{ \
size_t hash; \
struct n##_entry *entry; \
\
if (map->size + 1 > map->capacity * GEHASHMAP_LOAD_FACTOR) { \
if (n##_resize(map, map->capacity * 2) == -1) \
return -1; \
} \
\
hash = n##_key_hash(key) % map->capacity; \
entry = map->entries[hash]; \
while (entry != NULL) { \
if (n##_key_iseq(entry->key, key)) { \
entry->val = val; \
return 0; \
} \
entry = entry->next; \
} \
\
if ((entry = malloc(sizeof(struct n##_entry))) == NULL) \
return -1; \
\
entry->key = key; \
entry->val = val; \
entry->next = map->entries[hash]; \
map->entries[hash] = entry; \
map->size++; \
\
return 0; \
} \
\
/* Function to get an element from the hashmap. If “val” is NULL then
* no value will be retrieved. If an element with the given key is
* found in the hashmap the function returns true, otherwise false is
* returned.
*/ \
bool \
n##_get(n##_t *map, k key, v *val) \
{ \
size_t hash = n##_key_hash(key) % map->capacity; \
struct n##_entry *entry = map->entries[hash]; \
\
while (entry != NULL) { \
if (n##_key_iseq(entry->key, key)) { \
if (val != NULL) \
*val = entry->val; \
return true; \
} \
entry = entry->next; \
} \
\
return false; \
} \
\
/* Function to check if an element with a given key is contained within
* a hashmap. This is just a more readable wrapper around the n##_get()
* function that passes NULL as the last argument.
*/ \
bool \
n##_has(n##_t *map, k key) \
{ \
return n##_get(map, key, NULL); \
} \
\
/* Function to remove an element with a given key from a hashmap. If
* the value was dynamically allocated it will not be freed. The key
* will be freed however as per n##_key_free(). On error -1 is
* returned, otherwise 0 is returned.
*/ \
int \
n##_remove(n##_t *map, k key) \
{ \
size_t hash = n##_key_hash(key) % map->capacity; \
struct n##_entry *entry; \
\
if ((entry = map->entries[hash]) == NULL) \
return -1; \
\
if (n##_key_iseq(entry->key, key)) { \
map->entries[hash] = entry->next; \
n##_key_free(entry->key); \
free(entry); \
map->size--; \
return 0; \
} \
\
while (entry->next != NULL) { \
if (n##_key_iseq(entry->next->key, key)) { \
struct n##_entry *next = entry->next; \
entry->next = next->next; \
n##_key_free(next->key); \
free(next); \
map->size--; \
return 0; \
} \
entry = entry->next; \
} \
\
return -1; \
}
#endif /* !GEHASHMAP_H */
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