LibWeb: Introduce Mutation{Record,Observer} and observer microtasks

Userland/Libraries/LibWeb/DOM/MutationObserver.cpp

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Bindings/MainThreadVM.h>
+#include <LibWeb/Bindings/WindowObject.h>
+#include <LibWeb/DOM/MutationObserver.h>
+#include <LibWeb/DOM/Node.h>
+
+namespace Web::DOM {
+
+// https://dom.spec.whatwg.org/#dom-mutationobserver-mutationobserver
+MutationObserver::MutationObserver(Bindings::WindowObject& window_object, Bindings::CallbackType callback)
+    : m_callback(move(callback))
+{
+    // 1. Set this’s callback to callback.
+
+    // 2. Append this to this’s relevant agent’s mutation observers.
+    auto* agent_custom_data = verify_cast<Bindings::WebEngineCustomData>(window_object.vm().custom_data());
+    agent_custom_data->mutation_observers.append(*this);
+}
+
+// https://dom.spec.whatwg.org/#dom-mutationobserver-observe
+ExceptionOr<void> MutationObserver::observe(Node& target, MutationObserverInit options)
+{
+    // 1. If either options["attributeOldValue"] or options["attributeFilter"] exists, and options["attributes"] does not exist, then set options["attributes"] to true.
+    if ((options.attribute_old_value.has_value() || options.attribute_filter.has_value()) && !options.attributes.has_value())
+        options.attributes = true;
+
+    // 2. If options["characterDataOldValue"] exists and options["characterData"] does not exist, then set options["characterData"] to true.
+    if (options.character_data_old_value.has_value() && !options.character_data.has_value())
+        options.character_data = true;
+
+    // 3. If none of options["childList"], options["attributes"], and options["characterData"] is true, then throw a TypeError.
+    if (!options.child_list && (!options.attributes.has_value() || !options.attributes.value()) && (!options.character_data.has_value() || !options.character_data.value()))
+        return SimpleException { SimpleExceptionType::TypeError, "Options must have one of childList, attributes or characterData set to true." };
+
+    // 4. If options["attributeOldValue"] is true and options["attributes"] is false, then throw a TypeError.
+    // NOTE: If attributeOldValue is present, attributes will be present because of step 1.
+    if (options.attribute_old_value.has_value() && options.attribute_old_value.value() && !options.attributes.value())
+        return SimpleException { SimpleExceptionType::TypeError, "attributes must be true if attributeOldValue is true." };
+
+    // 5. If options["attributeFilter"] is present and options["attributes"] is false, then throw a TypeError.
+    // NOTE: If attributeFilter is present, attributes will be present because of step 1.
+    if (options.attribute_filter.has_value() && !options.attributes.value())
+        return SimpleException { SimpleExceptionType::TypeError, "attributes must be true if attributeFilter is present." };
+
+    // 6. If options["characterDataOldValue"] is true and options["characterData"] is false, then throw a TypeError.
+    // NOTE: If characterDataOldValue is present, characterData will be present because of step 2.
+    if (options.character_data_old_value.has_value() && options.character_data_old_value.value() && !options.character_data.value())
+        return SimpleException { SimpleExceptionType::TypeError, "characterData must be true if characterDataOldValue is true." };
+
+    // 7. For each registered of target’s registered observer list, if registered’s observer is this:
+    bool updated_existing_observer = false;
+    for (auto& registered_observer : target.registered_observers_list()) {
+        if (registered_observer.observer.ptr() != this)
+            continue;
+
+        updated_existing_observer = true;
+
+        // 1. For each node of this’s node list, remove all transient registered observers whose source is registered from node’s registered observer list.
+        for (auto& node : m_node_list) {
+            // FIXME: Is this correct?
+            if (node.is_null())
+                continue;
+
+            node->registered_observers_list().remove_all_matching([&registered_observer](RegisteredObserver& observer) {
+                return is<TransientRegisteredObserver>(observer) && verify_cast<TransientRegisteredObserver>(observer).source.ptr() == &registered_observer;
+            });
+        }
+
+        // 2. Set registered’s options to options.
+        registered_observer.options = options;
+        break;
+    }
+
+    // 8. Otherwise:
+    if (!updated_existing_observer) {
+        // 1. Append a new registered observer whose observer is this and options is options to target’s registered observer list.
+        auto new_registered_observer = RegisteredObserver::create(*this, options);
+        target.add_registered_observer(new_registered_observer);
+
+        // 2. Append target to this’s node list.
+        m_node_list.append(target.make_weak_ptr());
+    }
+
+    return {};
+}
+
+// https://dom.spec.whatwg.org/#dom-mutationobserver-disconnect
+void MutationObserver::disconnect()
+{
+    // 1. For each node of this’s node list, remove any registered observer from node’s registered observer list for which this is the observer.
+    for (auto& node : m_node_list) {
+        // FIXME: Is this correct?
+        if (node.is_null())
+            continue;
+
+        node->registered_observers_list().remove_all_matching([this](RegisteredObserver& registered_observer) {
+            return registered_observer.observer.ptr() == this;
+        });
+    }
+
+    // 2. Empty this’s record queue.
+    m_record_queue.clear();
+}
+
+// https://dom.spec.whatwg.org/#dom-mutationobserver-takerecords
+NonnullRefPtrVector<MutationRecord> MutationObserver::take_records()
+{
+    // 1. Let records be a clone of this’s record queue.
+    auto records = m_record_queue;
+
+    // 2. Empty this’s record queue.
+    m_record_queue.clear();
+
+    // 3. Return records.
+    return records;
+}
+
+}