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qbmap.h(3) libqb qbmap.h(3)

NAME

qbmap.h - This provides a map interface to a Patricia trie, hashtable or skiplist.

SYNOPSIS

#include <stdint.h>
#include <unistd.h>

Macros


#define QB_MAP_NOTIFY_DELETED 1
#define QB_MAP_NOTIFY_REPLACED 2
#define QB_MAP_NOTIFY_INSERTED 4
#define QB_MAP_NOTIFY_RECURSIVE 8
#define QB_MAP_NOTIFY_FREE 16

Typedefs


typedef struct qb_map qb_map_t
This is an opaque data type representing an instance of a map. typedef struct qb_map_iter qb_map_iter_t
This is an opaque data type representing an iterator instance. typedef void(* qb_map_notify_fn) (uint32_t event, char *key, void *old_value, void *value, void *user_data)
typedef int32_t(* qb_map_transverse_fn) (const char *key, void *value, void *user_data)

Functions


qb_map_t * qb_hashtable_create (size_t max_size)
Create an unsorted map based on a hashtable. qb_map_t * qb_skiplist_create (void)
Create a sorted map using a skiplist. qb_map_t * qb_trie_create (void)
Create a sorted map using a Patricia trie or 'Radix tree'. void qb_trie_dump (qb_map_t *m)
print out the nodes in the trie int32_t qb_map_notify_add (qb_map_t *m, const char *key, qb_map_notify_fn fn, int32_t events, void *user_data)
Add a notifier to the map. int32_t qb_map_notify_del (qb_map_t *m, const char *key, qb_map_notify_fn fn, int32_t events)
Delete a notifier from the map. int32_t qb_map_notify_del_2 (qb_map_t *m, const char *key, qb_map_notify_fn fn, int32_t events, void *user_data)
Delete a notifier from the map (including the userdata). void qb_map_put (qb_map_t *map, const char *key, const void *value)
Inserts a new key and value into a qb_map_t. void * qb_map_get (qb_map_t *map, const char *key)
Gets the value corresponding to the given key. int32_t qb_map_rm (qb_map_t *map, const char *key)
Removes a key/value pair from a map. size_t qb_map_count_get (qb_map_t *map)
Get the number of items in the map. void qb_map_foreach (qb_map_t *map, qb_map_transverse_fn func, void *user_data)
Calls the given function for each of the key/value pairs in the map. qb_map_iter_t * qb_map_iter_create (qb_map_t *map)
Create an iterator. qb_map_iter_t * qb_map_pref_iter_create (qb_map_t *map, const char *prefix)
Create a prefix iterator. const char * qb_map_iter_next (qb_map_iter_t *i, void **value)
Get the next item. void qb_map_iter_free (qb_map_iter_t *i)
free the iterator void qb_map_destroy (qb_map_t *map)
Destroy the map, removes all the items from the map.

Detailed Description

This provides a map interface to a Patricia trie, hashtable or skiplist.

Ordering

The hashtable is NOT ordered, but ptrie and skiplist are.

Iterating

Below is a simple example of how to iterate over a map. 

const char *p;
void *data;
qb_map_iter_t *it = qb_map_iter_create(m);
for (p = qb_map_iter_next(it, &data); p; p = qb_map_iter_next(it, &data)) {


    printf("%s > %s0, p, (char*) data);
}
qb_map_iter_free(it);

Deletion of items within the iterator is supported. But note do not free the item memory in the iterator. If you need to free the data items then register for a notifier and free the memory there. This is required as the items are reference counted.

qb_map_notify_add(m, NULL, my_map_free_handler,


             QB_MAP_NOTIFY_FREE, NULL);

Notifications

These allow you to get callbacks when values are inserted/removed or replaced.

Note:

hashtable only supports deletion and replacement notificatins. There is also a special global callback for freeing deleted and replaced values (QB_MAP_NOTIFY_FREE).

See also:

qb_map_notify_add() qb_map_notify_del_2()

Prefix matching

The ptrie supports prefixes in the iterator:

it = qb_map_pref_iter_create(m, "aa");
while ((p = qb_map_iter_next(it, &data)) != NULL) {


    printf("%s > %s0, p, (char*)data);
}
qb_map_iter_free(it);

The ptrie also supports prefixes in notifications: (remember to pass QB_MAP_NOTIFY_RECURSIVE into the notify_add.

qb_map_notify_add(m, "root", my_map_notification,


            (QB_MAP_NOTIFY_INSERTED|


             QB_MAP_NOTIFY_DELETED|


             QB_MAP_NOTIFY_REPLACED|


             QB_MAP_NOTIFY_RECURSIVE),


            NULL);

Macro Definition Documentation

#define QB_MAP_NOTIFY_DELETED 1

#define QB_MAP_NOTIFY_FREE 16

#define QB_MAP_NOTIFY_INSERTED 4

#define QB_MAP_NOTIFY_RECURSIVE 8

#define QB_MAP_NOTIFY_REPLACED 2

Typedef Documentation

typedef struct qb_map_iter qb_map_iter_t

This is an opaque data type representing an iterator instance.

typedef void(* qb_map_notify_fn) (uint32_t event, char *key, void *old_value, void *value, void *user_data)

typedef struct qb_map qb_map_t

This is an opaque data type representing an instance of a map.

typedef int32_t(* qb_map_transverse_fn) (const char *key, void *value, void *user_data)

Function Documentation

qb_map_t* qb_hashtable_create (size_t max_size)

Create an unsorted map based on a hashtable.

Parameters:

max_size maximum size of the hashtable

Returns:

the map instance

size_t qb_map_count_get (qb_map_t * map)

Get the number of items in the map.

void qb_map_destroy (qb_map_t * map)

Destroy the map, removes all the items from the map.

void qb_map_foreach (qb_map_t * map, qb_map_transverse_fn func, void * user_data)

Calls the given function for each of the key/value pairs in the map. The function is passed the key and value of each pair, and the given data parameter. The map is traversed in sorted order.

void* qb_map_get (qb_map_t * map, const char * key)

Gets the value corresponding to the given key.

Return values:

NULL (if the key does not exist)
a pointer to the value

qb_map_iter_t* qb_map_iter_create (qb_map_t * map)

Create an iterator.

void qb_map_iter_free (qb_map_iter_t * i)

free the iterator

Parameters:

i the iterator

const char* qb_map_iter_next (qb_map_iter_t * i, void ** value)

Get the next item.

Parameters:

i the iterator
value (out) the next item's value

Return values:

the next key
NULL - the end of the iteration

int32_t qb_map_notify_add (qb_map_t * m, const char * key, qb_map_notify_fn fn, int32_t events, void * user_data)

Add a notifier to the map.

Parameters:

m the map instance
key the key (or prefix) to attach the notification to.
fn the callback
events the type of events to register for.
user_data a pointer to be passed into the callback

Note:

QB_MAP_NOTIFY_INSERTED is only valid on tries.

you can use key prefixes with trie maps.

Return values:

0 success
-errno failure

int32_t qb_map_notify_del (qb_map_t * m, const char * key, qb_map_notify_fn fn, int32_t events)

Delete a notifier from the map.

Note:

the key,fn and events must match those you added.

Parameters:

m the map instance
key the key (or prefix) to attach the notification to.
fn the callback
events the type of events to register for.

Return values:

0 success
-errno failure

int32_t qb_map_notify_del_2 (qb_map_t * m, const char * key, qb_map_notify_fn fn, int32_t events, void * user_data)

Delete a notifier from the map (including the userdata).

Note:

the key, fn, events and userdata must match those you added.

Parameters:

m the map instance
key the key (or prefix) to attach the notification to.
fn the callback
events the type of events to register for.
user_data a pointer to be passed into the callback

Return values:

0 success
-errno failure

qb_map_iter_t* qb_map_pref_iter_create (qb_map_t * map, const char * prefix)

Create a prefix iterator. This will iterate over all items with the given prefix.

Note:

this is only supported by the trie.

void qb_map_put (qb_map_t * map, const char * key, const void * value)

Inserts a new key and value into a qb_map_t. If the key already exists in the qb_map_t, it gets replaced by the new key.

int32_t qb_map_rm (qb_map_t * map, const char * key)

Removes a key/value pair from a map.

qb_map_t* qb_skiplist_create (void)

Create a sorted map using a skiplist.

Returns:

the map instance

qb_map_t* qb_trie_create (void)

Create a sorted map using a Patricia trie or 'Radix tree'.

void qb_trie_dump (qb_map_t * m)

print out the nodes in the trie (for debug purposes)

Author

Generated automatically by Doxygen for libqb from the source code.

Fri Jan 13 2023 Version 1.0.3