LibJS: Move Cell.{cpp,h} from Runtime/ to Heap/

Userland/Libraries/LibJS/Heap/Cell.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Format.h>
+#include <AK/Forward.h>
+#include <AK/Noncopyable.h>
+#include <AK/String.h>
+#include <AK/TypeCasts.h>
+#include <LibJS/Forward.h>
+
+namespace JS {
+
+class Cell {
+    AK_MAKE_NONCOPYABLE(Cell);
+    AK_MAKE_NONMOVABLE(Cell);
+
+public:
+    virtual void initialize(GlobalObject&) { }
+    virtual ~Cell() { }
+
+    bool is_marked() const { return m_mark; }
+    void set_marked(bool b) { m_mark = b; }
+
+    bool is_live() const { return m_live; }
+    void set_live(bool b) { m_live = b; }
+
+    virtual const char* class_name() const = 0;
+
+    class Visitor {
+    public:
+        void visit(Cell*);
+        void visit(Value);
+
+    protected:
+        virtual void visit_impl(Cell*) = 0;
+        virtual ~Visitor() = default;
+    };
+
+    virtual void visit_edges(Visitor&) { }
+
+    Heap& heap() const;
+    VM& vm() const;
+
+protected:
+    Cell() { }
+
+private:
+    bool m_mark { false };
+    bool m_live { true };
+};
+
+}
+
+template<>
+struct AK::Formatter<JS::Cell> : AK::Formatter<FormatString> {
+    void format(FormatBuilder& builder, const JS::Cell* cell)
+    {
+        if (!cell)
+            Formatter<FormatString>::format(builder, "Cell{nullptr}");
+        else
+            Formatter<FormatString>::format(builder, "{}({})", cell->class_name(), cell);
+    }
+};