src/third_party/WebKit/Source/JavaScriptCore/runtime/IndexingType.h

/*
 * 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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef IndexingType_h
#define IndexingType_h

#include "SpeculatedType.h"
#include <wtf/StdLibExtras.h>

namespace JSC {

typedef uint8_t IndexingType;

// Flags for testing the presence of capabilities.
static const IndexingType IsArray                  = 1;

// The shape of the indexed property storage.
static const IndexingType IndexingShapeMask        = 30;
static const IndexingType NoIndexingShape          = 0;
static const IndexingType UndecidedShape           = 2; // Only useful for arrays.
static const IndexingType Int32Shape               = 20;
static const IndexingType DoubleShape              = 22;
static const IndexingType ContiguousShape          = 26;
static const IndexingType ArrayStorageShape        = 28;
static const IndexingType SlowPutArrayStorageShape = 30;

static const IndexingType IndexingShapeShift       = 1;
static const IndexingType NumberOfIndexingShapes   = 16;

// Additional flags for tracking the history of the type. These are usually
// masked off unless you ask for them directly.
static const IndexingType MayHaveIndexedAccessors  = 32;

// List of acceptable array types.
static const IndexingType NonArray                        = 0;
static const IndexingType NonArrayWithInt32               = Int32Shape;
static const IndexingType NonArrayWithDouble              = DoubleShape;
static const IndexingType NonArrayWithContiguous          = ContiguousShape;
static const IndexingType NonArrayWithArrayStorage        = ArrayStorageShape;
static const IndexingType NonArrayWithSlowPutArrayStorage = SlowPutArrayStorageShape;
static const IndexingType ArrayClass                      = IsArray; // I'd want to call this "Array" but this would lead to disastrous namespace pollution.
static const IndexingType ArrayWithUndecided              = IsArray | UndecidedShape;
static const IndexingType ArrayWithInt32                  = IsArray | Int32Shape;
static const IndexingType ArrayWithDouble                 = IsArray | DoubleShape;
static const IndexingType ArrayWithContiguous             = IsArray | ContiguousShape;
static const IndexingType ArrayWithArrayStorage           = IsArray | ArrayStorageShape;
static const IndexingType ArrayWithSlowPutArrayStorage    = IsArray | SlowPutArrayStorageShape;

#define ALL_BLANK_INDEXING_TYPES \
    NonArray:                    \
    case ArrayClass

#define ALL_UNDECIDED_INDEXING_TYPES \
    ArrayWithUndecided

#define ALL_INT32_INDEXING_TYPES      \
    NonArrayWithInt32:                \
    case ArrayWithInt32

#define ALL_DOUBLE_INDEXING_TYPES     \
    NonArrayWithDouble:               \
    case ArrayWithDouble

#define ALL_CONTIGUOUS_INDEXING_TYPES \
    NonArrayWithContiguous:           \
    case ArrayWithContiguous

#define ARRAY_WITH_ARRAY_STORAGE_INDEXING_TYPES \
    ArrayWithArrayStorage:                      \
    case ArrayWithSlowPutArrayStorage
    
#define ALL_ARRAY_STORAGE_INDEXING_TYPES                \
    NonArrayWithArrayStorage:                           \
    case NonArrayWithSlowPutArrayStorage:               \
    case ARRAY_WITH_ARRAY_STORAGE_INDEXING_TYPES

static inline bool hasIndexedProperties(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) != NoIndexingShape;
}

static inline bool hasIndexingHeader(IndexingType type)
{
    return hasIndexedProperties(type);
}

static inline bool hasUndecided(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == UndecidedShape;
}

static inline bool hasInt32(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == Int32Shape;
}

static inline bool hasDouble(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == DoubleShape;
}

static inline bool hasContiguous(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == ContiguousShape;
}

// FIXME: This is an awkward name. This should really be called hasArrayStorage()
// and then next method down should be called hasAnyArrayStorage().
static inline bool hasFastArrayStorage(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == ArrayStorageShape;
}

static inline bool hasArrayStorage(IndexingType indexingType)
{
    return static_cast<uint8_t>((indexingType & IndexingShapeMask) - ArrayStorageShape) <= static_cast<uint8_t>(SlowPutArrayStorageShape - ArrayStorageShape);
}

static inline bool shouldUseSlowPut(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == SlowPutArrayStorageShape;
}

// Return an indexing type that can handle all of the elements of both indexing types.
IndexingType leastUpperBoundOfIndexingTypes(IndexingType, IndexingType);

IndexingType leastUpperBoundOfIndexingTypeAndType(IndexingType, SpeculatedType);
IndexingType leastUpperBoundOfIndexingTypeAndValue(IndexingType, JSValue);

const char* indexingTypeToString(IndexingType);

// Mask of all possible types.
static const IndexingType AllArrayTypes            = 31;

// Mask of all possible types including the history.
static const IndexingType AllArrayTypesAndHistory  = 127;

} // namespace JSC

#endif // IndexingType_h