Libraries: Move to Userland/Libraries/

Userland/Libraries/LibJS/Heap/Handle.h

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Badge.h>
+#include <AK/Noncopyable.h>
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+#include <LibJS/Forward.h>
+
+namespace JS {
+
+class HandleImpl : public RefCounted<HandleImpl> {
+    AK_MAKE_NONCOPYABLE(HandleImpl);
+    AK_MAKE_NONMOVABLE(HandleImpl);
+
+public:
+    ~HandleImpl();
+
+    Cell* cell() { return m_cell; }
+    const Cell* cell() const { return m_cell; }
+
+private:
+    template<class T>
+    friend class Handle;
+
+    explicit HandleImpl(Cell*);
+    Cell* m_cell { nullptr };
+};
+
+template<class T>
+class Handle {
+public:
+    Handle() { }
+
+    static Handle create(T* cell)
+    {
+        return Handle(adopt(*new HandleImpl(cell)));
+    }
+
+    T* cell() { return static_cast<T*>(m_impl->cell()); }
+    const T* cell() const { return static_cast<const T*>(m_impl->cell()); }
+
+    bool is_null() const { return m_impl.is_null(); }
+
+private:
+    explicit Handle(NonnullRefPtr<HandleImpl> impl)
+        : m_impl(move(impl))
+    {
+    }
+
+    RefPtr<HandleImpl> m_impl;
+};
+
+template<class T>
+inline Handle<T> make_handle(T* cell)
+{
+    return Handle<T>::create(cell);
+}
+
+}