events.c

// /std/events.c
// Event emitter inheritible
// 
// Created:     2021/04/09: Gesslar
// Last Change: 2021/04/09: Gesslar
//
// 2021/04/09: Gesslar - Created

private static mapping event_listeners = ([ ]) ;

// Makes sure the event name is a proper string
int validate_event_name( string event_name )
{
    return !nullp( event_name ) && stringp( event_name ) && strlen( event_name ) > 0 ;
}

// Add a new event to the event_listeners mapping
nomask int add_event( string event_name )
{
    if( !validate_event_name( event_name ) ) return 0 ;
    if( !nullp( event_listeners[ event_name ] ) )  return 0 ;

    event_listeners[ event_name ] = ({ }) ;
    return 1 ;
}

// Remove an event from the event_listeners mapping
nomask int remove_event( string event_name )
{
    if( !validate_event_name( event_name ) ) return 0 ;
    if( nullp( event_listeners[ event_name ] ) )  return 0 ;

    map_delete( event_listeners, event_name ) ;
    return 1 ;
}

// Add a new listener to an existing, exposed event
nomask varargs int add_listener( string event_name, object listener )
{
    object *listeners ;

    if( !validate_event_name( event_name ) ) return 0 ;
    if( nullp( event_listeners[ event_name ] ) )  return 0 ;

    if( nullp( listener ) ) listener = previous_object() ;
    else if( !objectp( listener ) ) return 0 ;

    listeners = event_listeners[ event_name ] - ({ 0 }) ;
    if( member_array( listener, listeners ) > -1 ) return 0 ;

    listeners += ({ listener }) ;

    event_listeners[ event_name ] = listeners ;

    return 1 ;
}

// Remove a listener from an existing, exposed event
nomask varargs int remove_listener( string event_name, object listener )
{
    object *listeners ;

    if( !validate_event_name( event_name ) ) return 0 ;
    if( nullp( event_listeners[ event_name ] ) )  return 0 ;

    if( nullp( listener ) ) listener = previous_object() ;
    else if( !objectp( listener ) ) return 0 ;

    listeners = event_listeners[ event_name ] - ({ 0 }) ;
    if( member_array( listener, listeners ) == -1 ) return 0 ;

    listeners -= ({ listener }) ;

    event_listeners[ event_name ] = listeners ;

    return 1 ;
}

// Emit to all listeners the event name
void event_emit( string event_name, mixed *args... )
{
    object *listeners ;

    if( !validate_event_name( event_name ) ) return ;
    if( !pointerp( event_listeners[ event_name ] ) )  return ;
    if( nullp( event_listeners[ event_name ] ) ) return ; 

    listeners = event_listeners[ event_name ] - ({ 0 }) ;
    event_listeners[ event_name ] = listeners ;

    catch ( call_other( listeners, event_name, this_object(), args... ) ) ;
}