[apple/javascriptcore.git] / runtime / SymbolTable.h

/*
 * 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<UString::Rep>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, SymbolTableIndexHashTraits> SymbolTable;

} // namespace JSC

#endif // SymbolTable_h
Commit	Line	Data
9dae56ea A	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