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Commit	Line	Data
	1	/*
	2	* Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	*
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
	14	* its contributors may be used to endorse or promote products derived
	15	* from this software without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
	18	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	19	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	20	* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	21	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	22	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	23	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	24	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	27	*/
	28
	29	#ifndef SymbolTable_h
	30	#define SymbolTable_h
	31
	32	#include "JSObject.h"
	33	#include "UString.h"
	34	#include <wtf/AlwaysInline.h>
	35
	36	namespace JSC {
	37
	38	static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); }
	39
	40	// The bit twiddling in this class assumes that every register index is a
	41	// reasonably small positive or negative number, and therefore has its high
	42	// four bits all set or all unset.
	43
	44	struct SymbolTableEntry {
	45	SymbolTableEntry()
	46	: m_bits(0)
	47	{
	48	}
	49
	50	SymbolTableEntry(int index)
	51	{
	52	ASSERT(isValidIndex(index));
	53	pack(index, false, false);
	54	}
	55
	56	SymbolTableEntry(int index, unsigned attributes)
	57	{
	58	ASSERT(isValidIndex(index));
	59	pack(index, attributes & ReadOnly, attributes & DontEnum);
	60	}
	61
	62	bool isNull() const
	63	{
	64	return !m_bits;
	65	}
	66
	67	int getIndex() const
	68	{
	69	return m_bits >> FlagBits;
	70	}
	71
	72	unsigned getAttributes() const
	73	{
	74	unsigned attributes = 0;
	75	if (m_bits & ReadOnlyFlag)
	76	attributes \|= ReadOnly;
	77	if (m_bits & DontEnumFlag)
	78	attributes \|= DontEnum;
	79	return attributes;
	80	}
	81
	82	void setAttributes(unsigned attributes)
	83	{
	84	pack(getIndex(), attributes & ReadOnly, attributes & DontEnum);
	85	}
	86
	87	bool isReadOnly() const
	88	{
	89	return m_bits & ReadOnlyFlag;
	90	}
	91
	92	private:
	93	static const unsigned ReadOnlyFlag = 0x1;
	94	static const unsigned DontEnumFlag = 0x2;
	95	static const unsigned NotNullFlag = 0x4;
	96	static const unsigned FlagBits = 3;
	97
	98	void pack(int index, bool readOnly, bool dontEnum)
	99	{
	100	m_bits = (index << FlagBits) \| NotNullFlag;
	101	if (readOnly)
	102	m_bits \|= ReadOnlyFlag;
	103	if (dontEnum)
	104	m_bits \|= DontEnumFlag;
	105	}
	106
	107	bool isValidIndex(int index)
	108	{
	109	return ((index << FlagBits) >> FlagBits) == index;
	110	}
	111
	112	int m_bits;
	113	};
	114
	115	struct SymbolTableIndexHashTraits {
	116	typedef SymbolTableEntry TraitType;
	117	static SymbolTableEntry emptyValue() { return SymbolTableEntry(); }
	118	static const bool emptyValueIsZero = true;
	119	static const bool needsDestruction = false;
	120	};
	121
	122	typedef HashMap<RefPtr<UString::Rep>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, SymbolTableIndexHashTraits> SymbolTable;
	123
	124	} // namespace JSC
	125
	126	#endif // SymbolTable_h