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129 lines
4.2 KiB
Perl
129 lines
4.2 KiB
Perl
# File: EventDispatcher.pm
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#
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# Purpose: Registers event handlers and dispatches events to them.
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#
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# Note: PBot::Core::EventDispatcher has no relation to PBot::Core::EventQueue.
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# SPDX-FileCopyrightText: 2014-2023 Pragmatic Software <pragma78@gmail.com>
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# SPDX-License-Identifier: MIT
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package PBot::Core::EventDispatcher;
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use parent 'PBot::Core::Class';
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use PBot::Imports;
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use PBot::Core::Utils::PriorityQueue;
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sub initialize($self, %conf) {
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# hash table of event handlers
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$self->{handlers} = {};
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}
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# add an event handler
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#
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# priority ranges from 0 to 100. 0 is the highest priority, i.e. an handler with
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# priority 0 will handle events first. 100 is the lowest priority and will handle
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# events last. priority defaults to 50 if omitted.
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#
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# NickList reserves 0 and 100 to ensure its list is populated by JOINs, etc,
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# before any handlers need to consult its list, or depopulated by PARTs, QUITs,
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# KICKs, etc, after any other handlers need to consult its list.
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sub register_handler($self, $name, $subref, $priority = 50) {
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# get the package of the calling subroutine
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my ($package) = caller(0);
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# internal identifier to find calling package's event handler
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my $handler_id = "$package-$name";
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my $entry = {
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priority => $priority,
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id => $handler_id,
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subref => $subref,
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};
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# create new priority-queue for event-name if one doesn't exist
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if (not exists $self->{handlers}->{$name}) {
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$self->{handlers}->{$name} = PBot::Core::Utils::PriorityQueue->new(pbot => $self->{pbot});
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}
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# add the event handler
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$self->{handlers}->{$name}->add($entry);
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# debugging
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if ($self->{pbot}->{registry}->get_value('eventdispatcher', 'debug')) {
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$self->{pbot}->{logger}->log("EventDispatcher: Add handler: $handler_id\n");
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}
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}
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# remove an event handler
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sub remove_handler($self, $name) {
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# get the package of the calling subroutine
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my ($package) = caller(0);
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# internal identifier to find calling package's event handler
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my $handler_id = "$package-$name";
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# remove the event handler
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if (exists $self->{handlers}->{$name}) {
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my $handlers = $self->{handlers}->{$name};
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for (my $i = 0; $i < $handlers->count; $i++) {
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my $handler = $handlers->get($i);
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if ($handler->{id} eq $handler_id) {
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$handlers->remove($i--);
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}
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}
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# remove root event-name key if it has no more handlers
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if (not $self->{handlers}->{$name}->count) {
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delete $self->{handlers}->{$name};
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}
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}
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# debugging
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if ($self->{pbot}->{registry}->get_value('eventdispatcher', 'debug')) {
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$self->{pbot}->{logger}->log("EventDispatcher: Remove handler: $handler_id\n");
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}
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}
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# send an event to its handlers
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sub dispatch_event($self, $name, $data = undef) {
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# debugging flag
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my $debug = $self->{pbot}->{registry}->get_value('eventdispatcher', 'debug') // 0;
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# undef means no handlers have handled this event
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my $dispatch_result = undef;
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# if the event-name has handlers
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if (exists $self->{handlers}->{$name}) {
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# then dispatch the event to each one
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foreach my $handler ($self->{handlers}->{$name}->entries) {
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# debugging
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if ($debug) {
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$self->{pbot}->{logger}->log("Dispatching $name to handler $handler->{id}\n");
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}
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# invoke an event handler. a handler may return undef to indicate
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# that it decided not to handle this event.
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my $handler_result = eval { $handler->{subref}->($name, $data) };
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# check for exception
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if (my $exception = $@) {
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$self->{pbot}->{logger}->log("Exception in event handler: $exception");
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} else {
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# update $dispatch_result only when handler result is a defined
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# value so we remember if any handlers have handled this event.
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$dispatch_result = $handler_result if defined $handler_result;
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}
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}
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}
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# return undef if no handlers have handled this event; otherwise the return
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# value of the last event handler to handle this event.
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return $dispatch_result;
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}
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1;
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