LibWeb: Add NavigationDestination, used for NavigateEvents

This class will be used in the algorithms for the navigate event firing
algorithms to populate the destination field of the NavigateEvent.

Userland/Libraries/LibWeb/HTML/NavigationDestination.cpp

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2023, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Heap/Heap.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/NavigationDestinationPrototype.h>
+#include <LibWeb/HTML/NavigationDestination.h>
+#include <LibWeb/HTML/NavigationHistoryEntry.h>
+
+namespace Web::HTML {
+
+JS::NonnullGCPtr<NavigationDestination> NavigationDestination::create(JS::Realm& realm)
+{
+    return realm.heap().allocate<NavigationDestination>(realm, realm);
+}
+
+NavigationDestination::NavigationDestination(JS::Realm& realm)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+NavigationDestination::~NavigationDestination() = default;
+
+void NavigationDestination::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+    set_prototype(&Bindings::ensure_web_prototype<Bindings::NavigationDestinationPrototype>(realm, "NavigationDestination"));
+}
+
+void NavigationDestination::visit_edges(JS::Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_entry);
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-url
+WebIDL::ExceptionOr<String> NavigationDestination::url() const
+{
+    // The url getter steps are to return this's URL, serialized.
+    return TRY_OR_THROW_OOM(vm(), String::from_deprecated_string(m_url.serialize()));
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-key
+String NavigationDestination::key() const
+{
+    // The key getter steps are:
+
+    // 1. If this's entry is null, then return the empty string.
+    // 2. Return this's entry's key.
+    return (m_entry == nullptr) ? String {} : m_entry->key();
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-id
+String NavigationDestination::id() const
+{
+    // The id getter steps are:
+
+    // 1. If this's entry is null, then return the empty string.
+    // 2. Return this's entry's ID.
+    return (m_entry == nullptr) ? String {} : m_entry->id();
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-index
+i64 NavigationDestination::index() const
+{
+    // The index getter steps are:
+
+    // 1. If this's entry is null, then return -1.
+    // 2. Return this's entry's index.
+    return (m_entry == nullptr) ? -1 : m_entry->index();
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-samedocument
+bool NavigationDestination::same_document() const
+{
+    // The sameDocument getter steps are to return this's is same document.
+    return m_is_same_document;
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-getstate
+WebIDL::ExceptionOr<JS::Value> NavigationDestination::get_state()
+{
+    // The getState() method steps are to return StructuredDeserialize(this's state).
+    return structured_deserialize(vm(), m_state, realm(), {});
+}
+
+}