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/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Badge.h>
#include <AK/Format.h>
#include <AK/Forward.h>
#include <AK/Noncopyable.h>
#include <AK/StringView.h>
#include <LibJS/Forward.h>
#include <LibJS/Heap/GCPtr.h>
#include <LibJS/Runtime/Completion.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
#define JS_CELL(class_, base_class) \
public: \
using Base = base_class; \
virtual StringView class_name() const override \
{ \
return #class_##sv; \
} \
friend class JS::Heap;
class Cell {
AK_MAKE_NONCOPYABLE(Cell);
AK_MAKE_NONMOVABLE(Cell);
public:
virtual ThrowCompletionOr<void> initialize(Realm&) { return {}; }
virtual ~Cell() = default;
bool is_marked() const { return m_mark; }
void set_marked(bool b) { m_mark = b; }
enum class State {
Live,
Dead,
};
State state() const { return m_state; }
void set_state(State state) { m_state = state; }
virtual StringView class_name() const = 0;
class Visitor {
public:
void visit(Cell* cell)
{
if (cell)
visit_impl(*cell);
}
void visit(Cell& cell)
{
visit_impl(cell);
}
template<typename T>
void visit(GCPtr<T> cell)
{
if (cell)
visit_impl(const_cast<RemoveConst<T>&>(*cell.ptr()));
}
template<typename T>
void visit(NonnullGCPtr<T> cell)
{
visit_impl(const_cast<RemoveConst<T>&>(*cell.ptr()));
}
void visit(Value value)
{
if (value.is_cell())
visit_impl(value.as_cell());
}
// Allow explicitly ignoring a GC-allocated member in a visit_edges implementation instead
// of just not using it.
template<typename T>
void ignore(T const&)
{
}
protected:
virtual void visit_impl(Cell&) = 0;
virtual ~Visitor() = default;
};
virtual bool is_environment() const { return false; }
virtual void visit_edges(Visitor&) { }
// This will be called on unmarked objects by the garbage collector in a separate pass before destruction.
virtual void finalize() { }
// This allows cells to survive GC by choice, even if nothing points to them.
// It's used to implement special rules in the web platform.
// NOTE: Cells must call set_overrides_must_survive_garbage_collection() for this to be honored.
virtual bool must_survive_garbage_collection() const { return false; }
bool overrides_must_survive_garbage_collection(Badge<Heap>) const { return m_overrides_must_survive_garbage_collection; }
Heap& heap() const;
VM& vm() const;
protected:
Cell() = default;
void set_overrides_must_survive_garbage_collection(bool b) { m_overrides_must_survive_garbage_collection = b; }
private:
bool m_mark : 1 { false };
bool m_overrides_must_survive_garbage_collection : 1 { false };
State m_state : 1 { State::Live };
};
}
template<>
struct AK::Formatter<JS::Cell> : AK::Formatter<FormatString> {
ErrorOr<void> format(FormatBuilder& builder, JS::Cell const* cell)
{
if (!cell)
return builder.put_string("Cell{nullptr}"sv);
return Formatter<FormatString>::format(builder, "{}({})"sv, cell->class_name(), cell);
}
};
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