EventEmitter in C modeled after nodejs event emitter.
/* example.c */
#include <stdio.h>
#include <assert.h>
#include "ee.h"
void on_added_new_listener(void* arg) {
ee_new_listener_t *listener;
listener = (ee_new_listener_t*) arg;
printf("New listener added for event '%s'.\n", listener->name);
}
void on_hello(void* arg) {
char *s = (char*)arg;
printf("Invoked `on_hello` with '%s'\n", s);
}
void on_hi(void* arg) {
char *s = (char*)arg;
printf("Invoked `on_hi` with '%s'\n", s);
}
int main(void) {
const char *event_hello = "hello";
const char *event_hi = "hi";
ee_t *ee = ee_new();
ee_on(ee, EE_NEW_LISTENER, on_added_new_listener);
assert(0 == ee_listener_count(ee, event_hello));
/* subscribe "hello" indefinitely, "hi" only once */
ee_on(ee, event_hello, on_hello);
ee_once(ee, event_hi, on_hi);
assert(1 == ee_listener_count(ee, event_hello));
assert(1 == ee_listener_count(ee, event_hi));
ee_emit(ee, event_hello, "world");
ee_emit(ee, event_hi, "world");
assert(1 == ee_listener_count(ee, event_hello));
assert(0 == ee_listener_count(ee, event_hi));
ee_emit(ee, event_hello, "world");
ee_emit(ee, event_hi, "world"); /* => nothing happens */
ee_remove_listener(ee, event_hello, on_hello);
assert(0 == ee_listener_count(ee, event_hello));
ee_emit(ee, event_hello, "world"); /* => nothing happens */
return 0;
}$ make example
New listener added for event 'hello'.
New listener added for event 'hi'.
Invoked `on_hello` with 'world'
Invoked `on_hi` with 'world'
Invoked `on_hello` with 'world'
clib install thlorenz/ee.c
Matches API of nodejs event emitter so that a large part of its documentation applies here.
/*
* Callbacks
*/
/*
* Callback to register when adding an event listener for all events except EE_NEW_LISTENER.
*/
typedef void (*ee_cb)(void*);
/*
* Callback to register when adding an event listener for EE_NEW_LISTENER.
*/
typedef void (*ee_new_listener_cb)(ee_new_listener_t* listener);
/*
* structs
*/
/*
* new listener struct used as an argument for EE_NEW_LISTENER event
*
* @name: name of event for which a listener was added
* @cb: the callback that was registered for that event
*/
struct ee_new_listener_s {
const char *name;
ee_cb cb;
};
/*
* ee struct which stores all information about the event emitter
*
* @events: a list of all registered events with this emitter
*/
typedef struct {
/* private */
list_t /*<ee__event_t>*/ *events;
} ee_t;
/*
* methods
*/
/*
* create/destroy
*/
/*
* Initializes new event emitter and returns the result
*/
ee_t* ee_new ( );
/*
* Frees the event emitter
*/
void ee_destroy ( ee_t* self);
/*
* adding listeners
*/
/*
* Registers the given callback for the event of the given name.
* Now whenever an event is with that name is emitted, the callback is invoked.
*
* @self: the event emitter
* @name: the name of the event we are registering
* @cb: the callback to invoke when the event is triggered
*/
void ee_on ( ee_t* self, const char* name, const ee_cb cb);
/*
* Synonym for `on`
*/
void ee_add_listener ( ee_t* self, const char* name, const ee_cb cb);
/*
* Same as `on`, except that the even listener will be automatically removed after the event was emitted once.
*/
void ee_once ( ee_t* self, const char* name, const ee_cb cb);
/*
* removing listeners
*/
/*
* Removes the given listener for the event with the given name.
* If the listener was registered more than once, only the first is removed.
* If the listener was not registered, nothing is done.
*
* @self: the event emitter
* @name: the name of the event we are removing the listener for
* @cb: the callback to remove
*/
void ee_remove_listener ( ee_t* self, const char* name, const ee_cb cb);
/*
* Removes all listeners for the event with the given name.
* If no listeners for this event were registered, nothing is done.
*
* @self: the event emitter
* @name: the name of the event we are removing the listeners for
*/
void ee_remove_all_listeners ( ee_t* self, const char* name);
/*
* emitting events
*/
/*
* Emit an event with the given name and argument
*
* @self: the event emitter
* @name: the name of the event we are emitting
* @arg: event arg
*/
void ee_emit ( ee_t* self, const char* name, void* arg);
/*
* inspecting listeners
*/
/*
* Get all listeners for a given event.
*
* @self: the event emitter
* @name: the name of the event we are getting listeners of
* @return a list_t<ee_handler_t> of listeners
*/
list_t* /*<ee_handler_t>*/ ee_listeners ( ee_t* self, const char* name);
/*
* Get how many listeners are subscribe for a given event
*
* @self: the event emitter
* @name: the name of the event we are getting listeners count for
* @return number of listeners
*/
int ee_listener_count ( ee_t* self, const char* name);MIT