3
0
mirror of https://github.com/pragma-/pbot.git synced 2024-12-24 11:42:35 +01:00
pbot/lib/PBot/EventDispatcher.pm
2021-07-13 19:45:56 -07:00

110 lines
3.3 KiB
Perl

# File: EventDispatcher.pm
#
# Purpose: Registers event handlers and dispatches events to them.
#
# Note: PBot::EventDispatcher has no relation to PBot::EventQueue.
# SPDX-FileCopyrightText: 2021 Pragmatic Software <pragma78@gmail.com>
# SPDX-License-Identifier: MIT
package PBot::EventDispatcher;
use parent 'PBot::Class';
use PBot::Imports;
sub initialize {
my ($self, %conf) = @_;
# hash table of event handlers
$self->{handlers} = {};
}
# add an event handler
sub register_handler {
my ($self, $event_name, $subref) = @_;
# get the package of the calling subroutine
my ($package) = caller(0);
# internal identifier to find calling package's event handler
my $handler_id = "$package-$event_name";
# add the event handler
$self->{handlers}->{$event_name}->{$handler_id} = $subref;
# debugging
if ($self->{pbot}->{registry}->get_value('eventdispatcher', 'debug')) {
$self->{pbot}->{logger}->log("EventDispatcher: Add handler: $handler_id\n");
}
}
# remove an event handler
sub remove_handler {
my ($self, $event_name) = @_;
# get the package of the calling subroutine
my ($package) = caller(0);
# internal identifier to find calling package's event handler
my $handler_id = "$package-$event_name";
# remove the event handler
if (exists $self->{handlers}->{$event_name}) {
delete $self->{handlers}->{$event_name}->{$handler_id};
# remove root event-name key if it has no more handlers
if (not keys %{$self->{handlers}->{$event_name}}) {
delete $self->{handlers}->{$event_name};
}
}
# debugging
if ($self->{pbot}->{registry}->get_value('eventdispatcher', 'debug')) {
$self->{pbot}->{logger}->log("EventDispatcher: Remove handler: $handler_id\n");
}
}
# send an event to its handlers
sub dispatch_event {
my ($self, $event_name, $event_data) = @_;
# debugging flag
my $debug = $self->{pbot}->{registry}->get_value('eventdispatcher', 'debug') // 0;
# undef means no handlers have handled this event
my $dispatch_result= undef;
# if the event-name has handlers
if (exists $self->{handlers}->{$event_name}) {
# then dispatch the event to each one
foreach my $handler_id (keys %{$self->{handlers}->{$event_name}}) {
# get event handler subref
my $subref = $self->{handlers}->{$event_name}->{$handler_id};
# debugging
if ($debug) {
$self->{pbot}->{logger}->log("Dispatching $event_name to handler $handler_id\n");
}
# invoke an event handler. a handler may return undef to indicate
# that it decided not to handle this event.
my $handler_result = eval { $subref->($event_name, $event_data) };
# update $dispatch_result only when handler result is a defined
# value so we remember if any handlers have handled this event.
$dispatch_result = $handler_result if defined $handler_result;
# check for exception
if (my $exception = $@) {
$self->{pbot}->{logger}->log("Exception in event handler: $exception");
}
}
}
# return undef if no handlers have handled this event; otherwise the return
# value of the last event handler to handle this event.
return $dispatch_result;
}
1;