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+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QHASHFIELD_P_H
+#define QHASHFIELD_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+// QHashField can be used for doing coarse grained set testing, in
+// cases where you do not expect the set to contain the item.  For
+// example where you would write:
+//     QSet<QString> strings;
+//     for (int ii = 0; ii < mystrings.count(); ++ii) {
+//         if (strings.contains(mystrings.at(ii))) 
+//             qFatal("Duplication!");
+//         strings.insert(mystrings);
+//     }
+// You may write:
+//     QHashField strings;
+//     for (int ii = 0; ii < mystrings.count(); ++ii) {
+//         if (strings.testAndSet(qHash(mystrings.at(ii)))) {
+//             // The string *might* be duplicated
+//             for (int jj = 0; jj < ii; ++jj) {
+//                 if (mystrings.at(ii) == mystrings.at(jj)) 
+//                     qFatal("Duplication!");
+//             }
+//          }
+//     }
+// For small lists of things, where the hash is cheap to calculate
+// and you don't expect duplication this will be much faster.
+class QHashField {
+public:
+    inline QHashField();
+
+    inline void clear();
+
+    inline bool test(quint32 hash);
+    inline bool testAndSet(quint32 hash);
+private:
+    quint32 m_field;
+};
+
+QHashField::QHashField()
+: m_field(0)
+{
+}
+
+void QHashField::clear()
+{
+    m_field = 0;
+}
+
+bool QHashField::test(quint32 hash)
+{
+    return m_field & (1 << (hash % 31));
+}
+
+bool QHashField::testAndSet(quint32 hash)
+{
+    quint32 mask = 1 << (hash % 31);
+    bool rv = m_field & mask;
+    m_field |= mask;
+    return rv;
+}
+
+QT_END_NAMESPACE
+
+#endif // QHASHFIELD_P_H