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107 lines (90 loc) · 4.6 KB
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/*
* Copyright (C) 2012 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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 ArrayStorage_h
#define ArrayStorage_h
#include "ArrayConventions.h"
#include "Butterfly.h"
#include "IndexingHeader.h"
#include "SparseArrayValueMap.h"
#include "WriteBarrier.h"
#include <wtf/Noncopyable.h>
namespace JSC {
// This struct holds the actual data values of an array. A JSArray object points to its contained ArrayStorage
// struct by pointing to m_vector. To access the contained ArrayStorage struct, use the getStorage() and
// setStorage() methods. It is important to note that there may be space before the ArrayStorage that
// is used to quick unshift / shift operation. The actual allocated pointer is available by using:
// getStorage() - m_indexBias * sizeof(JSValue)
// All slots in ArrayStorage (slots from 0 to vectorLength) are expected to be initialized to a JSValue or,
// for hole slots, JSValue().
struct ArrayStorage {
WTF_MAKE_NONCOPYABLE(ArrayStorage);
private:
ArrayStorage() { } // Not directly instantiable. Can only be created as part of a Butterfly.
public:
static ArrayStorage* from(Butterfly* butterfly) { return reinterpret_cast_ptr<ArrayStorage*>(butterfly); }
static ArrayStorage* from(IndexingHeader* indexingHeader) { return indexingHeader->arrayStorage(); }
Butterfly* butterfly() { return reinterpret_cast<Butterfly*>(this); }
IndexingHeader* indexingHeader() { return IndexingHeader::from(this); }
const IndexingHeader* indexingHeader() const { return IndexingHeader::from(this); }
// We steal two fields from the indexing header: vectorLength and length.
unsigned length() const { return indexingHeader()->publicLength(); }
void setLength(unsigned length) { indexingHeader()->setPublicLength(length); }
unsigned vectorLength() { return indexingHeader()->vectorLength(); }
void setVectorLength(unsigned length) { indexingHeader()->setVectorLength(length); }
ALWAYS_INLINE void copyHeaderFromDuringGC(const ArrayStorage& other)
{
m_sparseMap.copyFrom(other.m_sparseMap);
m_indexBias = other.m_indexBias;
m_numValuesInVector = other.m_numValuesInVector;
}
bool hasHoles() const
{
return m_numValuesInVector != length();
}
bool inSparseMode()
{
return m_sparseMap && m_sparseMap->sparseMode();
}
ContiguousJSValues vector() { return ContiguousJSValues(m_vector, vectorLength()); }
WriteBarrier<SparseArrayValueMap> m_sparseMap;
unsigned m_indexBias;
unsigned m_numValuesInVector;
#if USE(JSVALUE32_64)
uintptr_t m_padding;
#endif
WriteBarrier<Unknown> m_vector[1];
static ptrdiff_t lengthOffset() { return Butterfly::offsetOfPublicLength(); }
static ptrdiff_t vectorLengthOffset() { return Butterfly::offsetOfVectorLength(); }
static ptrdiff_t numValuesInVectorOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_numValuesInVector); }
static ptrdiff_t vectorOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_vector); }
static ptrdiff_t indexBiasOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_indexBias); }
static ptrdiff_t sparseMapOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_sparseMap); }
static size_t sizeFor(unsigned vectorLength)
{
return ArrayStorage::vectorOffset() + vectorLength * sizeof(WriteBarrier<Unknown>);
}
};
} // namespace JSC
#endif // ArrayStorage_h