/* * Copyright (C) 2016 Apple Inc. 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 APPLE INC. AND ITS 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 APPLE INC. OR ITS 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 namespace JSC { class JSCell; class VM; // An Auxiliary barrier is a barrier that does not try to reason about the value being stored into // it, other than interpreting a falsy value as not needing a barrier. It's OK to use this for either // JSCells or any other kind of data, so long as it responds to operator!(). template<typename T> class AuxiliaryBarrier { public: typedef T Type; AuxiliaryBarrier(): m_value() { } template<typename U> AuxiliaryBarrier(VM&, JSCell*, U&&); void clear() { m_value = T(); } template<typename U> void set(VM&, JSCell*, U&&); const T& get() const { return m_value; } T* slot() { return &m_value; } explicit operator bool() const { return !!m_value; } template<typename U> void setWithoutBarrier(U&& value) { m_value = std::forward<U>(value); } T operator->() const { return get(); } private: T m_value; }; } // namespace JSC