LibJS: Add PrivateEnvironment

Userland/Libraries/LibJS/Runtime/PrivateEnvironment.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2021, David Tuin <davidot@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+#include <LibJS/Heap/Cell.h>
+
+namespace JS {
+
+struct PrivateName {
+    PrivateName(u64 unique_id, FlyString description)
+        : unique_id(unique_id)
+        , description(move(description))
+    {
+    }
+
+    u64 unique_id { 0 };
+    FlyString description;
+
+    bool operator==(PrivateName const& rhs) const;
+};
+
+class PrivateEnvironment : public Cell {
+public:
+    explicit PrivateEnvironment(PrivateEnvironment* parent);
+
+    PrivateName resolve_private_identifier(FlyString const& identifier) const;
+
+    void add_private_name(Badge<ClassExpression>, FlyString description);
+
+private:
+    virtual char const* class_name() const override { return "PrivateEnvironment"; }
+
+    auto find_private_name(FlyString const& description) const
+    {
+        return m_private_names.find_if([&](PrivateName const& private_name) {
+            return private_name.description == description;
+        });
+    }
+
+    static u64 s_next_id;
+
+    PrivateEnvironment* m_outer_environment { nullptr }; // [[OuterEnv]]
+    Vector<PrivateName> m_private_names;                 // [[Names]]
+    u64 m_unique_id;
+};
+
+}