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/*
* Copyright (C) 2007, 2008 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE 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 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.
*/
#ifndef SymbolTable_h
#define SymbolTable_h
#include "JSObject.h"
#include "UString.h"
#include <wtf/AlwaysInline.h>
namespace JSC {
static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); }
// The bit twiddling in this class assumes that every register index is a
// reasonably small positive or negative number, and therefore has its high
// four bits all set or all unset.
struct SymbolTableEntry {
SymbolTableEntry()
: m_bits(0)
{
}
SymbolTableEntry(int index)
{
ASSERT(isValidIndex(index));
pack(index, false, false);
}
SymbolTableEntry(int index, unsigned attributes)
{
ASSERT(isValidIndex(index));
pack(index, attributes & ReadOnly, attributes & DontEnum);
}
bool isNull() const
{
return !m_bits;
}
int getIndex() const
{
return m_bits >> FlagBits;
}
unsigned getAttributes() const
{
unsigned attributes = 0;
if (m_bits & ReadOnlyFlag)
attributes |= ReadOnly;
if (m_bits & DontEnumFlag)
attributes |= DontEnum;
return attributes;
}
void setAttributes(unsigned attributes)
{
pack(getIndex(), attributes & ReadOnly, attributes & DontEnum);
}
bool isReadOnly() const
{
return m_bits & ReadOnlyFlag;
}
private:
static const unsigned ReadOnlyFlag = 0x1;
static const unsigned DontEnumFlag = 0x2;
static const unsigned NotNullFlag = 0x4;
static const unsigned FlagBits = 3;
void pack(int index, bool readOnly, bool dontEnum)
{
m_bits = (index << FlagBits) | NotNullFlag;
if (readOnly)
m_bits |= ReadOnlyFlag;
if (dontEnum)
m_bits |= DontEnumFlag;
}
bool isValidIndex(int index)
{
return ((index << FlagBits) >> FlagBits) == index;
}
int m_bits;
};
struct SymbolTableIndexHashTraits {
typedef SymbolTableEntry TraitType;
static SymbolTableEntry emptyValue() { return SymbolTableEntry(); }
static const bool emptyValueIsZero = true;
static const bool needsDestruction = false;
};
typedef HashMap<RefPtr<StringImpl>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<StringImpl> >, SymbolTableIndexHashTraits> SymbolTable;
class SharedSymbolTable : public SymbolTable, public RefCounted<SharedSymbolTable> {
WTF_MAKE_FAST_ALLOCATED;
public:
static PassRefPtr<SharedSymbolTable> create() { return adoptRef(new SharedSymbolTable); }
private:
SharedSymbolTable() { }
};
} // namespace JSC
#endif // SymbolTable_h
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