/*

 *  Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Library General Public

 *  License as published by the Free Software Foundation; either

 *  version 2 of the License, or (at your option) any later version.

 *

 *  This library is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 *  Library General Public License for more details.

 *

 *  You should have received a copy of the GNU Library General Public License

 *  along with this library; see the file COPYING.LIB.  If not, write to

 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 *  Boston, MA 02110-1301, USA.

 *

 */

#ifndef PropertyMapHashTable_h

#define PropertyMapHashTable_h

#include "UString.h"

#include <wtf/Vector.h>

namespace JSC {

    struct PropertyMapEntry {

        UString::Rep* key;

        unsigned offset;

        unsigned attributes;

        JSCell* specificValue;

        unsigned index;

        PropertyMapEntry(UString::Rep* key, unsigned attributes, JSCell* specificValue)

            : key(key)

            , offset(0)

            , attributes(attributes)

            , specificValue(specificValue)

            , index(0)

        {

        }

        PropertyMapEntry(UString::Rep* key, unsigned offset, unsigned attributes, JSCell* specificValue, unsigned index)

            : key(key)

            , offset(offset)

            , attributes(attributes)

            , specificValue(specificValue)

            , index(index)

        {

        }

    };

    // lastIndexUsed is an ever-increasing index used to identify the order items

    // were inserted into the property map. It's required that getEnumerablePropertyNames

    // return the properties in the order they were added for compatibility with other

    // browsers' JavaScript implementations.

    struct PropertyMapHashTable {

        unsigned sizeMask;

        unsigned size;

        unsigned keyCount;

        unsigned deletedSentinelCount;

        unsigned lastIndexUsed;

        Vector<unsigned>* deletedOffsets;

        unsigned entryIndices[1];

        PropertyMapEntry* entries()

        {

            // The entries vector comes after the indices vector.

            // The 0th item in the entries vector is not really used; it has to

            // have a 0 in its key to allow the hash table lookup to handle deleted

            // sentinels without any special-case code, but the other fields are unused.

            return reinterpret_cast<PropertyMapEntry*>(&entryIndices[size]);

        }

        static size_t allocationSize(unsigned size)

        {

            // We never let a hash table get more than half full,

            // So the number of indices we need is the size of the hash table.

            // But the number of entries is half that (plus one for the deleted sentinel).

            return sizeof(PropertyMapHashTable)

                + (size - 1) * sizeof(unsigned)

                + (1 + size / 2) * sizeof(PropertyMapEntry);

        }

    };

} // namespace JSC

#endif // PropertyMapHashTable_h