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/*
* 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
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