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* Copyright (C) 2011 Apple Inc. All rights reserved.
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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#ifndef StringRecursionChecker_h
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#define StringRecursionChecker_h
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#include "Interpreter.h"
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#include <wtf/StackStats.h>
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#include <wtf/WTFThreadData.h>
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class StringRecursionChecker {
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WTF_MAKE_NONCOPYABLE(StringRecursionChecker);
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StringRecursionChecker(ExecState*, JSObject* thisObject);
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~StringRecursionChecker();
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JSValue earlyReturnValue() const; // 0 if everything is OK, value to return for failure cases
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JSValue throwStackOverflowError();
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JSValue emptyString();
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JSValue performCheck();
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JSObject* m_thisObject;
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JSValue m_earlyReturnValue;
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StackStats::CheckPoint stackCheckpoint;
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inline JSValue StringRecursionChecker::performCheck()
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const StackBounds& nativeStack = wtfThreadData().stack();
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if (!nativeStack.isSafeToRecurse())
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return throwStackOverflowError();
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bool alreadyVisited = !m_exec->globalData().stringRecursionCheckVisitedObjects.add(m_thisObject).isNewEntry;
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return emptyString(); // Return empty string to avoid infinite recursion.
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return JSValue(); // Indicate success.
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inline StringRecursionChecker::StringRecursionChecker(ExecState* exec, JSObject* thisObject)
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, m_thisObject(thisObject)
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, m_earlyReturnValue(performCheck())
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inline JSValue StringRecursionChecker::earlyReturnValue() const
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return m_earlyReturnValue;
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inline StringRecursionChecker::~StringRecursionChecker()
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if (m_earlyReturnValue)
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ASSERT(m_exec->globalData().stringRecursionCheckVisitedObjects.contains(m_thisObject));
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m_exec->globalData().stringRecursionCheckVisitedObjects.remove(m_thisObject);