Userland: Rename Core::Object to Core::EventReceiver

This is a more precise description of what this class actually does.

Userland/Libraries/LibCore/EventReceiver.cpp

@@ -0,0 +1,184 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Assertions.h>
+#include <AK/Badge.h>
+#include <AK/JsonObject.h>
+#include <LibCore/Event.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/EventReceiver.h>
+#include <stdio.h>
+
+namespace Core {
+
+EventReceiver::EventReceiver(EventReceiver* parent)
+    : m_parent(parent)
+{
+    if (m_parent)
+        m_parent->add_child(*this);
+}
+
+EventReceiver::~EventReceiver()
+{
+    // NOTE: We move our children out to a stack vector to prevent other
+    //       code from trying to iterate over them.
+    auto children = move(m_children);
+    // NOTE: We also unparent the children, so that they won't try to unparent
+    //       themselves in their own destructors.
+    for (auto& child : children)
+        child->m_parent = nullptr;
+
+    stop_timer();
+    if (m_parent)
+        m_parent->remove_child(*this);
+}
+
+void EventReceiver::event(Core::Event& event)
+{
+    switch (event.type()) {
+    case Core::Event::Timer:
+        return timer_event(static_cast<TimerEvent&>(event));
+    case Core::Event::ChildAdded:
+    case Core::Event::ChildRemoved:
+        return child_event(static_cast<ChildEvent&>(event));
+    case Core::Event::Invalid:
+        VERIFY_NOT_REACHED();
+        break;
+    case Core::Event::Custom:
+        return custom_event(static_cast<CustomEvent&>(event));
+    default:
+        break;
+    }
+}
+
+ErrorOr<void> EventReceiver::try_add_child(EventReceiver& object)
+{
+    // FIXME: Should we support reparenting objects?
+    VERIFY(!object.parent() || object.parent() == this);
+    TRY(m_children.try_append(object));
+    object.m_parent = this;
+    Core::ChildEvent child_event(Core::Event::ChildAdded, object);
+    event(child_event);
+    return {};
+}
+
+void EventReceiver::add_child(EventReceiver& object)
+{
+    MUST(try_add_child(object));
+}
+
+void EventReceiver::insert_child_before(EventReceiver& new_child, EventReceiver& before_child)
+{
+    // FIXME: Should we support reparenting objects?
+    VERIFY(!new_child.parent() || new_child.parent() == this);
+    new_child.m_parent = this;
+    m_children.insert_before_matching(new_child, [&](auto& existing_child) { return existing_child.ptr() == &before_child; });
+    Core::ChildEvent child_event(Core::Event::ChildAdded, new_child, &before_child);
+    event(child_event);
+}
+
+void EventReceiver::remove_child(EventReceiver& object)
+{
+    for (size_t i = 0; i < m_children.size(); ++i) {
+        if (m_children[i] == &object) {
+            // NOTE: We protect the child so it survives the handling of ChildRemoved.
+            NonnullRefPtr<EventReceiver> protector = object;
+            object.m_parent = nullptr;
+            m_children.remove(i);
+            Core::ChildEvent child_event(Core::Event::ChildRemoved, object);
+            event(child_event);
+            return;
+        }
+    }
+    VERIFY_NOT_REACHED();
+}
+
+void EventReceiver::remove_all_children()
+{
+    while (!m_children.is_empty())
+        m_children.first()->remove_from_parent();
+}
+
+void EventReceiver::timer_event(Core::TimerEvent&)
+{
+}
+
+void EventReceiver::child_event(Core::ChildEvent&)
+{
+}
+
+void EventReceiver::custom_event(CustomEvent&)
+{
+}
+
+void EventReceiver::start_timer(int ms, TimerShouldFireWhenNotVisible fire_when_not_visible)
+{
+    if (m_timer_id) {
+        dbgln("{} {:p} already has a timer!", class_name(), this);
+        VERIFY_NOT_REACHED();
+    }
+
+    m_timer_id = Core::EventLoop::register_timer(*this, ms, true, fire_when_not_visible);
+}
+
+void EventReceiver::stop_timer()
+{
+    if (!m_timer_id)
+        return;
+    bool success = Core::EventLoop::unregister_timer(m_timer_id);
+    if (!success) {
+        dbgln("{} {:p} could not unregister timer {}", class_name(), this, m_timer_id);
+    }
+    m_timer_id = 0;
+}
+
+void EventReceiver::deferred_invoke(Function<void()> invokee)
+{
+    Core::deferred_invoke([invokee = move(invokee), strong_this = NonnullRefPtr(*this)] { invokee(); });
+}
+
+bool EventReceiver::is_ancestor_of(EventReceiver const& other) const
+{
+    if (&other == this)
+        return false;
+    for (auto* ancestor = other.parent(); ancestor; ancestor = ancestor->parent()) {
+        if (ancestor == this)
+            return true;
+    }
+    return false;
+}
+
+void EventReceiver::dispatch_event(Core::Event& e, EventReceiver* stay_within)
+{
+    VERIFY(!stay_within || stay_within == this || stay_within->is_ancestor_of(*this));
+    auto* target = this;
+    do {
+        // If there's an event filter on this target, ask if it wants to swallow this event.
+        if (target->m_event_filter && !target->m_event_filter(e))
+            return;
+        target->event(e);
+        target = target->parent();
+        if (target == stay_within) {
+            // Prevent the event from bubbling any further.
+            return;
+        }
+    } while (target && !e.is_accepted());
+}
+
+bool EventReceiver::is_visible_for_timer_purposes() const
+{
+    if (parent())
+        return parent()->is_visible_for_timer_purposes();
+    return true;
+}
+
+void EventReceiver::set_event_filter(Function<bool(Core::Event&)> filter)
+{
+    m_event_filter = move(filter);
+}
+
+}