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;
+}
+
+}

Userland/Libraries/LibWeb/DOM/MutationObserver.h

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/RefCounted.h>
+#include <LibJS/Heap/Handle.h>
+#include <LibWeb/Bindings/CallbackType.h>
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/DOM/ExceptionOr.h>
+#include <LibWeb/DOM/MutationRecord.h>
+
+namespace Web::DOM {
+
+// https://dom.spec.whatwg.org/#dictdef-mutationobserverinit
+struct MutationObserverInit {
+    bool child_list { false };
+    Optional<bool> attributes;
+    Optional<bool> character_data;
+    bool subtree { false };
+    Optional<bool> attribute_old_value;
+    Optional<bool> character_data_old_value;
+    Optional<Vector<String>> attribute_filter;
+};
+
+// https://dom.spec.whatwg.org/#mutationobserver
+class MutationObserver final
+    : public RefCounted<MutationObserver>
+    , public Bindings::Wrappable {
+public:
+    using WrapperType = Bindings::MutationObserverWrapper;
+
+    static NonnullRefPtr<MutationObserver> create_with_global_object(Bindings::WindowObject& window_object, Bindings::CallbackType callback)
+    {
+        return adopt_ref(*new MutationObserver(window_object, move(callback)));
+    }
+
+    virtual ~MutationObserver() override = default;
+
+    ExceptionOr<void> observe(Node& target, MutationObserverInit options = {});
+    void disconnect();
+    NonnullRefPtrVector<MutationRecord> take_records();
+
+    Vector<WeakPtr<Node>>& node_list() { return m_node_list; }
+    Vector<WeakPtr<Node>> const& node_list() const { return m_node_list; }
+
+    Bindings::CallbackType& callback() { return m_callback; }
+
+    void enqueue_record(Badge<Node>, NonnullRefPtr<MutationRecord> mutation_record)
+    {
+        m_record_queue.append(move(mutation_record));
+    }
+
+private:
+    MutationObserver(Bindings::WindowObject& window_object, Bindings::CallbackType callback);
+
+    // https://dom.spec.whatwg.org/#concept-mo-callback
+    Bindings::CallbackType m_callback;
+
+    // https://dom.spec.whatwg.org/#mutationobserver-node-list
+    Vector<WeakPtr<Node>> m_node_list;
+
+    // https://dom.spec.whatwg.org/#concept-mo-queue
+    NonnullRefPtrVector<MutationRecord> m_record_queue;
+};
+
+// https://dom.spec.whatwg.org/#registered-observer
+struct RegisteredObserver : public RefCounted<RegisteredObserver> {
+    static NonnullRefPtr<RegisteredObserver> create(MutationObserver& observer, MutationObserverInit& options)
+    {
+        return adopt_ref(*new RegisteredObserver(observer, options));
+    }
+
+    RegisteredObserver(MutationObserver& observer, MutationObserverInit& options)
+        : observer(observer)
+        , options(options)
+    {
+    }
+
+    virtual ~RegisteredObserver() = default;
+
+    NonnullRefPtr<MutationObserver> observer;
+    MutationObserverInit options;
+};
+
+// https://dom.spec.whatwg.org/#transient-registered-observer
+struct TransientRegisteredObserver final : public RegisteredObserver {
+    static NonnullRefPtr<TransientRegisteredObserver> create(MutationObserver& observer, MutationObserverInit& options, RegisteredObserver& source)
+    {
+        return adopt_ref(*new TransientRegisteredObserver(observer, options, source));
+    }
+
+    TransientRegisteredObserver(MutationObserver& observer, MutationObserverInit& options, RegisteredObserver& source)
+        : RegisteredObserver(observer, options)
+        , source(source)
+    {
+    }
+
+    virtual ~TransientRegisteredObserver() override = default;
+
+    NonnullRefPtr<RegisteredObserver> source;
+};
+
+}

Userland/Libraries/LibWeb/DOM/MutationObserver.idl

@@ -0,0 +1,27 @@
+#import <DOM/MutationRecord.idl>
+#import <DOM/Node.idl>
+
+[Exposed=Window]
+interface MutationObserver {
+
+    constructor(MutationCallback callback);
+
+    undefined observe(Node target, optional MutationObserverInit options = {});
+    undefined disconnect();
+    sequence<MutationRecord> takeRecords();
+
+};
+
+callback MutationCallback = undefined (sequence<MutationRecord> mutations, MutationObserver observer);
+
+dictionary MutationObserverInit {
+
+    boolean childList = false;
+    boolean attributes;
+    boolean characterData;
+    boolean subtree = false;
+    boolean attributeOldValue;
+    boolean characterDataOldValue;
+    sequence<DOMString> attributeFilter;
+
+};

Userland/Libraries/LibWeb/DOM/MutationRecord.cpp

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/DOM/MutationRecord.h>
+#include <LibWeb/DOM/Node.h>
+#include <LibWeb/DOM/NodeList.h>
+
+namespace Web::DOM {
+
+class MutationRecordImpl final : public MutationRecord {
+public:
+    MutationRecordImpl(FlyString const& type, Node& target, NodeList& added_nodes, NodeList& removed_nodes, Node* previous_sibling, Node* next_sibling, String const& attribute_name, String const& attribute_namespace, String const& old_value)
+        : m_type(type)
+        , m_target(target)
+        , m_added_nodes(added_nodes)
+        , m_removed_nodes(removed_nodes)
+        , m_previous_sibling(previous_sibling)
+        , m_next_sibling(next_sibling)
+        , m_attribute_name(attribute_name)
+        , m_attribute_namespace(attribute_namespace)
+        , m_old_value(old_value)
+    {
+    }
+
+    virtual ~MutationRecordImpl() override = default;
+
+    virtual FlyString const& type() const override { return m_type; }
+    virtual Node const* target() const override { return m_target; }
+    virtual NodeList const* added_nodes() const override { return m_added_nodes; }
+    virtual NodeList const* removed_nodes() const override { return m_removed_nodes; }
+    virtual Node const* previous_sibling() const override { return m_previous_sibling; }
+    virtual Node const* next_sibling() const override { return m_next_sibling; }
+    virtual String const& attribute_name() const override { return m_attribute_name; }
+    virtual String const& attribute_namespace() const override { return m_attribute_namespace; }
+    virtual String const& old_value() const override { return m_old_value; }
+
+private:
+    FlyString m_type;
+    NonnullRefPtr<Node> m_target;
+    NonnullRefPtr<NodeList> m_added_nodes;
+    NonnullRefPtr<NodeList> m_removed_nodes;
+    RefPtr<Node> m_previous_sibling;
+    RefPtr<Node> m_next_sibling;
+    String m_attribute_name;
+    String m_attribute_namespace;
+    String m_old_value;
+};
+
+NonnullRefPtr<MutationRecord> MutationRecord::create(FlyString const& type, Node& target, NodeList& added_nodes, NodeList& removed_nodes, Node* previous_sibling, Node* next_sibling, String const& attribute_name, String const& attribute_namespace, String const& old_value)
+{
+    return adopt_ref(*new MutationRecordImpl(type, target, added_nodes, removed_nodes, previous_sibling, next_sibling, attribute_name, attribute_namespace, old_value));
+}
+
+}

Userland/Libraries/LibWeb/DOM/MutationRecord.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/RefCounted.h>
+#include <LibWeb/Bindings/Wrappable.h>
+
+namespace Web::DOM {
+
+// https://dom.spec.whatwg.org/#mutationrecord
+// NOTE: This is implemented as a pure virtual interface with the actual implementation in the CPP file to prevent this circular dependency: Node.h -> MutationRecord.h -> MutationObserver.h -> Node.h
+//       This is also why this uses raw pointers and references, since using (NN)RP requires us to include the templated type, even in a header specifying a function return type.
+class MutationRecord
+    : public RefCounted<MutationRecord>
+    , public Bindings::Wrappable {
+public:
+    using WrapperType = Bindings::MutationRecordWrapper;
+
+    static NonnullRefPtr<MutationRecord> create(FlyString const& type, Node& target, NodeList& added_nodes, NodeList& removed_nodes, Node* previous_sibling, Node* next_sibling, String const& attribute_name, String const& attribute_namespace, String const& old_value);
+
+    virtual ~MutationRecord() override = default;
+
+    virtual FlyString const& type() const = 0;
+    virtual Node const* target() const = 0;
+    virtual NodeList const* added_nodes() const = 0;
+    virtual NodeList const* removed_nodes() const = 0;
+    virtual Node const* previous_sibling() const = 0;
+    virtual Node const* next_sibling() const = 0;
+    virtual String const& attribute_name() const = 0;
+    virtual String const& attribute_namespace() const = 0;
+    virtual String const& old_value() const = 0;
+};
+
+}

Userland/Libraries/LibWeb/DOM/MutationRecord.idl

@@ -0,0 +1,17 @@
+#import <DOM/Node.idl>
+#import <DOM/NodeList.idl>
+
+[Exposed=Window]
+interface MutationRecord {
+
+    readonly attribute DOMString type;
+    [SameObject] readonly attribute Node target;
+    [SameObject] readonly attribute NodeList addedNodes;
+    [SameObject] readonly attribute NodeList removedNodes;
+    readonly attribute Node? previousSibling;
+    readonly attribute Node? nextSibling;
+    readonly attribute DOMString? attributeName;
+    readonly attribute DOMString? attributeNamespace;
+    readonly attribute DOMString? oldValue;
+
+};

Userland/Libraries/LibWeb/DOM/MutationType.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/DOM/MutationType.h>
+
+namespace Web::DOM::MutationType {
+
+#define __ENUMERATE_MUTATION_TYPE(name) FlyString name;
+ENUMERATE_MUTATION_TYPES
+#undef __ENUMERATE_MUTATION_TYPE
+
+[[gnu::constructor]] static void initialize()
+{
+    static bool s_initialized = false;
+    if (s_initialized)
+        return;
+
+#define __ENUMERATE_MUTATION_TYPE(name) name = #name;
+    ENUMERATE_MUTATION_TYPES
+#undef __ENUMERATE_MUTATION_TYPE
+
+    s_initialized = true;
+}
+
+}

Userland/Libraries/LibWeb/DOM/MutationType.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+
+namespace Web::DOM::MutationType {
+
+#define ENUMERATE_MUTATION_TYPES             \
+    __ENUMERATE_MUTATION_TYPE(attributes)    \
+    __ENUMERATE_MUTATION_TYPE(characterData) \
+    __ENUMERATE_MUTATION_TYPE(childList)
+
+#define __ENUMERATE_MUTATION_TYPE(name) extern FlyString name;
+ENUMERATE_MUTATION_TYPES
+#undef __ENUMERATE_MUTATION_TYPE
+
+}

Userland/Libraries/LibWeb/DOM/Node.h

@@ -15,6 +15,7 @@
 #include <LibWeb/Bindings/Wrappable.h>
 #include <LibWeb/DOM/EventTarget.h>
 #include <LibWeb/DOM/ExceptionOr.h>
+#include <LibWeb/DOM/MutationObserver.h>
 #include <LibWeb/TreeNode.h>
 
 namespace Web::DOM {
@@ -223,6 +224,11 @@ public:
 
     size_t length() const;
 
+    NonnullRefPtrVector<RegisteredObserver>& registered_observers_list() { return m_registered_observer_list; }
+    NonnullRefPtrVector<RegisteredObserver> const& registered_observers_list() const { return m_registered_observer_list; }
+
+    void add_registered_observer(RegisteredObserver& registered_observer) { m_registered_observer_list.append(registered_observer); }
+
 protected:
     Node(Document&, NodeType);
 
@@ -233,6 +239,10 @@ protected:
     bool m_child_needs_style_update { false };
 
     i32 m_id;
+
+    // https://dom.spec.whatwg.org/#registered-observer-list
+    // "Nodes have a strong reference to registered observers in their registered observer list." https://dom.spec.whatwg.org/#garbage-collection
+    NonnullRefPtrVector<RegisteredObserver> m_registered_observer_list;
 };
 
 }