JSArray.cpp 71.8 KB
Newer Older
darin's avatar
darin committed
1 2
/*
 *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
3
 *  Copyright (C) 2003, 2007, 2008, 2009 Apple Inc. All rights reserved.
darin's avatar
darin committed
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
 *  Copyright (C) 2003 Peter Kelly (pmk@post.com)
 *  Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "config.h"
darin@apple.com's avatar
darin@apple.com committed
24
#include "JSArray.h"
darin's avatar
darin committed
25

darin@apple.com's avatar
darin@apple.com committed
26
#include "ArrayPrototype.h"
27
#include "CachedCall.h"
28
#include "Error.h"
29
#include "Executable.h"
30
#include "GetterSetter.h"
darin's avatar
darin committed
31
#include "PropertyNameArray.h"
ap@webkit.org's avatar
ap@webkit.org committed
32
#include <wtf/AVLTree.h>
33
#include <wtf/Assertions.h>
34
#include <wtf/OwnPtr.h>
35
#include <Operations.h>
darin's avatar
darin committed
36

37
using namespace std;
ap@webkit.org's avatar
ap@webkit.org committed
38
using namespace WTF;
bdash's avatar
bdash committed
39

40
namespace JSC {
darin's avatar
darin committed
41

ggaren@apple.com's avatar
ggaren@apple.com committed
42 43
ASSERT_CLASS_FITS_IN_CELL(JSArray);

barraclough@apple.com's avatar
barraclough@apple.com committed
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
// Overview of JSArray
//
// Properties of JSArray objects may be stored in one of three locations:
//   * The regular JSObject property map.
//   * A storage vector.
//   * A sparse map of array entries.
//
// Properties with non-numeric identifiers, with identifiers that are not representable
// as an unsigned integer, or where the value is greater than  MAX_ARRAY_INDEX
// (specifically, this is only one property - the value 0xFFFFFFFFU as an unsigned 32-bit
// integer) are not considered array indices and will be stored in the JSObject property map.
//
// All properties with a numeric identifer, representable as an unsigned integer i,
// where (i <= MAX_ARRAY_INDEX), are an array index and will be stored in either the
// storage vector or the sparse map.  An array index i will be handled in the following
// fashion:
//
61 62
//   * Where (i < MIN_SPARSE_ARRAY_INDEX) the value will be stored in the storage vector,
//     unless the array is in SparseMode in which case all properties go into the map.
barraclough@apple.com's avatar
barraclough@apple.com committed
63 64 65 66 67 68 69 70 71
//   * Where (MIN_SPARSE_ARRAY_INDEX <= i <= MAX_STORAGE_VECTOR_INDEX) the value will either
//     be stored in the storage vector or in the sparse array, depending on the density of
//     data that would be stored in the vector (a vector being used where at least
//     (1 / minDensityMultiplier) of the entries would be populated).
//   * Where (MAX_STORAGE_VECTOR_INDEX < i <= MAX_ARRAY_INDEX) the value will always be stored
//     in the sparse array.

// The definition of MAX_STORAGE_VECTOR_LENGTH is dependant on the definition storageSize
// function below - the MAX_STORAGE_VECTOR_LENGTH limit is defined such that the storage
72 73 74
// size calculation cannot overflow.  (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>)) +
// (vectorLength * sizeof(WriteBarrier<Unknown>)) must be <= 0xFFFFFFFFU (which is maximum value of size_t).
#define MAX_STORAGE_VECTOR_LENGTH static_cast<unsigned>((0xFFFFFFFFU - (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>))) / sizeof(WriteBarrier<Unknown>))
barraclough@apple.com's avatar
barraclough@apple.com committed
75 76 77 78 79

// These values have to be macros to be used in max() and min() without introducing
// a PIC branch in Mach-O binaries, see <rdar://problem/5971391>.
#define MIN_SPARSE_ARRAY_INDEX 10000U
#define MAX_STORAGE_VECTOR_INDEX (MAX_STORAGE_VECTOR_LENGTH - 1)
80
// 0xFFFFFFFF is a bit weird -- is not an array index even though it's an integer.
barraclough@apple.com's avatar
barraclough@apple.com committed
81
#define MAX_ARRAY_INDEX 0xFFFFFFFEU
darin's avatar
darin committed
82

83 84 85 86 87 88 89 90
// The value BASE_VECTOR_LEN is the maximum number of vector elements we'll allocate
// for an array that was created with a sepcified length (e.g. a = new Array(123))
#define BASE_VECTOR_LEN 4U
    
// The upper bound to the size we'll grow a zero length array when the first element
// is added.
#define FIRST_VECTOR_GROW 4U

darin's avatar
darin committed
91
// Our policy for when to use a vector and when to use a sparse map.
barraclough@apple.com's avatar
barraclough@apple.com committed
92 93
// For all array indices under MIN_SPARSE_ARRAY_INDEX, we always use a vector.
// When indices greater than MIN_SPARSE_ARRAY_INDEX are involved, we use a vector
darin's avatar
darin committed
94 95 96
// as long as it is 1/8 full. If more sparse than that, we use a map.
static const unsigned minDensityMultiplier = 8;

97
const ClassInfo JSArray::s_info = {"Array", &JSNonFinalObject::s_info, 0, 0, CREATE_METHOD_TABLE(JSArray)};
darin's avatar
darin committed
98

99 100 101 102 103
// We keep track of the size of the last array after it was grown.  We use this
// as a simple heuristic for as the value to grow the next array from size 0.
// This value is capped by the constant FIRST_VECTOR_GROW defined above.
static unsigned lastArraySize = 0;

darin's avatar
darin committed
104 105
static inline size_t storageSize(unsigned vectorLength)
{
barraclough@apple.com's avatar
barraclough@apple.com committed
106 107 108 109
    ASSERT(vectorLength <= MAX_STORAGE_VECTOR_LENGTH);

    // MAX_STORAGE_VECTOR_LENGTH is defined such that provided (vectorLength <= MAX_STORAGE_VECTOR_LENGTH)
    // - as asserted above - the following calculation cannot overflow.
110
    size_t size = (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>)) + (vectorLength * sizeof(WriteBarrier<Unknown>));
barraclough@apple.com's avatar
barraclough@apple.com committed
111 112
    // Assertion to detect integer overflow in previous calculation (should not be possible, provided that
    // MAX_STORAGE_VECTOR_LENGTH is correctly defined).
113
    ASSERT(((size - (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>))) / sizeof(WriteBarrier<Unknown>) == vectorLength) && (size >= (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>))));
barraclough@apple.com's avatar
barraclough@apple.com committed
114 115

    return size;
darin's avatar
darin committed
116 117 118 119
}

static inline bool isDenseEnoughForVector(unsigned length, unsigned numValues)
{
120
    return length <= MIN_SPARSE_ARRAY_INDEX || length / minDensityMultiplier <= numValues;
darin's avatar
darin committed
121 122
}

123 124
#if !CHECK_ARRAY_CONSISTENCY

darin@apple.com's avatar
darin@apple.com committed
125
inline void JSArray::checkConsistency(ConsistencyCheckType)
126 127 128 129 130
{
}

#endif

131 132
JSArray::JSArray(JSGlobalData& globalData, Structure* structure)
    : JSNonFinalObject(globalData, structure)
133
    , m_storage(0)
weinig@apple.com's avatar
weinig@apple.com committed
134
{
135 136
}

137
void JSArray::finishCreation(JSGlobalData& globalData, unsigned initialLength)
138 139
{
    Base::finishCreation(globalData);
140 141
    ASSERT(inherits(&s_info));

142 143
    unsigned initialVectorLength = BASE_VECTOR_LEN;
    unsigned initialStorageSize = storageSize(initialVectorLength);
weinig@apple.com's avatar
weinig@apple.com committed
144

145
    m_storage = static_cast<ArrayStorage*>(fastMalloc(initialStorageSize));
146
    m_storage->m_allocBase = m_storage;
147
    m_storage->m_length = initialLength;
148
    m_indexBias = 0;
149 150 151 152 153 154 155
    m_vectorLength = initialVectorLength;
    m_storage->m_sparseValueMap = 0;
    m_storage->subclassData = 0;
    m_storage->m_numValuesInVector = 0;
#if CHECK_ARRAY_CONSISTENCY
    m_storage->m_inCompactInitialization = false;
#endif
weinig@apple.com's avatar
weinig@apple.com committed
156

157 158 159
    WriteBarrier<Unknown>* vector = m_storage->m_vector;
    for (size_t i = 0; i < initialVectorLength; ++i)
        vector[i].clear();
160

161 162 163
    checkConsistency();
    
    Heap::heap(this)->reportExtraMemoryCost(initialStorageSize);
weinig@apple.com's avatar
weinig@apple.com committed
164 165
}

166
JSArray* JSArray::tryFinishCreationUninitialized(JSGlobalData& globalData, unsigned initialLength)
darin's avatar
darin committed
167
{
168
    Base::finishCreation(globalData);
169 170
    ASSERT(inherits(&s_info));

171 172 173 174 175 176 177 178
    // Check for lengths larger than we can handle with a vector.
    if (initialLength > MAX_STORAGE_VECTOR_LENGTH)
        return 0;

    unsigned initialVectorLength = max(initialLength, BASE_VECTOR_LEN);
    unsigned initialStorageSize = storageSize(initialVectorLength);

    m_storage = static_cast<ArrayStorage*>(fastMalloc(initialStorageSize));
179
    m_storage->m_allocBase = m_storage;
180
    m_storage->m_length = 0;
181
    m_indexBias = 0;
182
    m_vectorLength = initialVectorLength;
183 184
    m_storage->m_sparseValueMap = 0;
    m_storage->subclassData = 0;
185
    m_storage->m_numValuesInVector = initialLength;
186
#if CHECK_ARRAY_CONSISTENCY
187
    m_storage->m_inCompactInitialization = true;
188
#endif
189

190 191 192 193 194 195
    WriteBarrier<Unknown>* vector = m_storage->m_vector;
    for (size_t i = initialLength; i < initialVectorLength; ++i)
        vector[i].clear();

    Heap::heap(this)->reportExtraMemoryCost(initialStorageSize);
    return this;
darin's avatar
darin committed
196 197
}

darin@apple.com's avatar
darin@apple.com committed
198
JSArray::~JSArray()
darin's avatar
darin committed
199
{
200
    ASSERT(jsCast<JSArray*>(this));
201

202 203 204 205 206
    // If we are unable to allocate memory for m_storage then this may be null.
    if (!m_storage)
        return;

    checkConsistency(DestructorConsistencyCheck);
207 208
    delete m_storage->m_sparseValueMap;
    fastFree(m_storage->m_allocBase);
darin's avatar
darin committed
209 210
}

211 212 213 214 215
void JSArray::destroy(JSCell* cell)
{
    jsCast<JSArray*>(cell)->JSArray::~JSArray();
}

216
inline std::pair<SparseArrayValueMap::iterator, bool> SparseArrayValueMap::add(JSArray* array, unsigned i)
217
{
218 219 220 221 222 223 224 225
    SparseArrayEntry entry;
    std::pair<iterator, bool> result = m_map.add(i, entry);
    size_t capacity = m_map.capacity();
    if (capacity != m_reportedCapacity) {
        Heap::heap(array)->reportExtraMemoryCost((capacity - m_reportedCapacity) * (sizeof(unsigned) + sizeof(WriteBarrier<Unknown>)));
        m_reportedCapacity = capacity;
    }
    return result;
226 227
}

228
inline void SparseArrayValueMap::put(ExecState* exec, JSArray* array, unsigned i, JSValue value)
229
{
230 231
    SparseArrayEntry& entry = add(array, i).first->second;

232
    if (!(entry.attributes & Accessor)) {
233 234 235 236 237 238 239
        if (entry.attributes & ReadOnly) {
            // FIXME: should throw if being called from strict mode.
            // throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
            return;
        }

        entry.set(exec->globalData(), array, value);
240
        return;
241
    }
242

243 244 245 246 247 248 249
    JSValue accessor = entry.Base::get();
    ASSERT(accessor.isGetterSetter());
    JSObject* setter = asGetterSetter(accessor)->setter();
    
    if (!setter) {
        throwTypeError(exec, "setting a property that has only a getter");
        return;
250
    }
251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303

    CallData callData;
    CallType callType = setter->methodTable()->getCallData(setter, callData);
    MarkedArgumentBuffer args;
    args.append(value);
    call(exec, setter, callType, callData, array, args);
}

inline void SparseArrayEntry::get(PropertySlot& slot) const
{
    JSValue value = Base::get();
    ASSERT(value);

    if (LIKELY(!value.isGetterSetter())) {
        slot.setValue(value);
        return;
    }

    JSObject* getter = asGetterSetter(value)->getter();
    if (!getter) {
        slot.setUndefined();
        return;
    }

    slot.setGetterSlot(getter);
}

inline void SparseArrayEntry::get(PropertyDescriptor& descriptor) const
{
    descriptor.setDescriptor(Base::get(), attributes);
}

inline JSValue SparseArrayEntry::get(ExecState* exec, JSArray* array) const
{
    JSValue result = Base::get();
    ASSERT(result);

    if (LIKELY(!result.isGetterSetter()))
        return result;

    JSObject* getter = asGetterSetter(result)->getter();
    if (!getter)
        return jsUndefined();

    CallData callData;
    CallType callType = getter->methodTable()->getCallData(getter, callData);
    return call(exec, getter, callType, callData, array, exec->emptyList());
}

inline JSValue SparseArrayEntry::getNonSparseMode() const
{
    ASSERT(!attributes);
    return Base::get();
304 305 306 307 308 309 310 311 312
}

inline void SparseArrayValueMap::visitChildren(SlotVisitor& visitor)
{
    iterator end = m_map.end();
    for (iterator it = m_map.begin(); it != end; ++it)
        visitor.append(&it->second);
}

313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348
void JSArray::enterSparseMode(JSGlobalData& globalData)
{
    ArrayStorage* storage = m_storage;
    SparseArrayValueMap* map = storage->m_sparseValueMap;

    if (!map)
        map = storage->m_sparseValueMap = new SparseArrayValueMap;

    if (map->sparseMode())
        return;

    map->setSparseMode();

    unsigned usedVectorLength = min(storage->m_length, m_vectorLength);
    for (unsigned i = 0; i < usedVectorLength; ++i) {
        JSValue value = storage->m_vector[i].get();
        // This will always be a new entry in the map, so no need to check we can write,
        // and attributes are default so no need to set them.
        if (value)
            map->add(this, i).first->second.set(globalData, this, value);
    }

    ArrayStorage* newStorage = static_cast<ArrayStorage*>(fastMalloc(storageSize(0)));
    memcpy(newStorage, m_storage, storageSize(0));
    newStorage->m_allocBase = newStorage;
    fastFree(m_storage);
    m_storage = newStorage;
    m_indexBias = 0;
    m_vectorLength = 0;
}

void JSArray::putDescriptor(ExecState* exec, SparseArrayEntry* entryInMap, PropertyDescriptor& descriptor, PropertyDescriptor& oldDescriptor)
{
    if (descriptor.isDataDescriptor()) {
        if (descriptor.value())
            entryInMap->set(exec->globalData(), this, descriptor.value());
349 350
        else if (oldDescriptor.isAccessorDescriptor())
            entryInMap->set(exec->globalData(), this, jsUndefined());
351
        entryInMap->attributes = descriptor.attributesOverridingCurrent(oldDescriptor) & ~Accessor;
352 353 354 355 356
        return;
    }

    if (descriptor.isAccessorDescriptor()) {
        JSObject* getter = 0;
357 358 359 360
        if (descriptor.getterPresent())
            getter = descriptor.getterObject();
        else if (oldDescriptor.isAccessorDescriptor())
            getter = oldDescriptor.getterObject();
361
        JSObject* setter = 0;
362 363 364 365
        if (descriptor.setterPresent())
            setter = descriptor.setterObject();
        else if (oldDescriptor.isAccessorDescriptor())
            setter = oldDescriptor.setterObject();
366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454

        GetterSetter* accessor = GetterSetter::create(exec);
        if (getter)
            accessor->setGetter(exec->globalData(), getter);
        if (setter)
            accessor->setSetter(exec->globalData(), setter);

        entryInMap->set(exec->globalData(), this, accessor);
        entryInMap->attributes = descriptor.attributesOverridingCurrent(oldDescriptor) & ~DontDelete;
        return;
    }

    ASSERT(descriptor.isGenericDescriptor());
    entryInMap->attributes = descriptor.attributesOverridingCurrent(oldDescriptor);
}

static bool reject(ExecState* exec, bool throwException, const char* message)
{
    if (throwException)
        throwTypeError(exec, message);
    return false;
}

// Defined in ES5.1 8.12.9
bool JSArray::defineOwnNumericProperty(ExecState* exec, unsigned index, PropertyDescriptor& descriptor, bool throwException)
{
    ASSERT(index != 0xFFFFFFFF);

    if (!inSparseMode()) {
        // Fast case: we're putting a regular property to a regular array
        // FIXME: this will pessimistically assume that if attributes are missing then they'll default to false
        // – however if the property currently exists missing attributes will override from their current 'true'
        // state (i.e. defineOwnProperty could be used to set a value without needing to entering 'SparseMode').
        if (!descriptor.attributes()) {
            ASSERT(!descriptor.isAccessorDescriptor());
            putByIndex(this, exec, index, descriptor.value());
            return true;
        }

        enterSparseMode(exec->globalData());
    }

    SparseArrayValueMap* map = m_storage->m_sparseValueMap;
    ASSERT(map);

    // 1. Let current be the result of calling the [[GetOwnProperty]] internal method of O with property name P.
    std::pair<SparseArrayValueMap::iterator, bool> result = map->add(this, index);
    SparseArrayEntry* entryInMap = &result.first->second;

    // 2. Let extensible be the value of the [[Extensible]] internal property of O.
    // 3. If current is undefined and extensible is false, then Reject.
    // 4. If current is undefined and extensible is true, then
    if (result.second) {
        if (!isExtensible()) {
            map->remove(result.first);
            return reject(exec, throwException, "Attempting to define property on object that is not extensible.");
        }

        // 4.a. If IsGenericDescriptor(Desc) or IsDataDescriptor(Desc) is true, then create an own data property
        // named P of object O whose [[Value]], [[Writable]], [[Enumerable]] and [[Configurable]] attribute values
        // are described by Desc. If the value of an attribute field of Desc is absent, the attribute of the newly
        // created property is set to its default value.
        // 4.b. Else, Desc must be an accessor Property Descriptor so, create an own accessor property named P of
        // object O whose [[Get]], [[Set]], [[Enumerable]] and [[Configurable]] attribute values are described by
        // Desc. If the value of an attribute field of Desc is absent, the attribute of the newly created property
        // is set to its default value.
        // 4.c. Return true.

        PropertyDescriptor defaults;
        entryInMap->setWithoutWriteBarrier(jsUndefined());
        entryInMap->attributes = DontDelete | DontEnum | ReadOnly;
        entryInMap->get(defaults);

        putDescriptor(exec, entryInMap, descriptor, defaults);
        if (index >= m_storage->m_length)
            m_storage->m_length = index + 1;
        return true;
    }

    // 5. Return true, if every field in Desc is absent.
    // 6. Return true, if every field in Desc also occurs in current and the value of every field in Desc is the same value as the corresponding field in current when compared using the SameValue algorithm (9.12).
    PropertyDescriptor current;
    entryInMap->get(current);
    if (descriptor.isEmpty() || descriptor.equalTo(exec, current))
        return true;

    // 7. If the [[Configurable]] field of current is false then
    if (!current.configurable()) {
        // 7.a. Reject, if the [[Configurable]] field of Desc is true.
455
        if (descriptor.configurablePresent() && !descriptor.configurable())
456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489
            return reject(exec, throwException, "Attempting to change configurable attribute of unconfigurable property.");
        // 7.b. Reject, if the [[Enumerable]] field of Desc is present and the [[Enumerable]] fields of current and Desc are the Boolean negation of each other.
        if (descriptor.enumerablePresent() && current.enumerable() != descriptor.enumerable())
            return reject(exec, throwException, "Attempting to change enumerable attribute of unconfigurable property.");
    }

    // 8. If IsGenericDescriptor(Desc) is true, then no further validation is required.
    if (!descriptor.isGenericDescriptor()) {
        // 9. Else, if IsDataDescriptor(current) and IsDataDescriptor(Desc) have different results, then
        if (current.isDataDescriptor() != descriptor.isDataDescriptor()) {
            // 9.a. Reject, if the [[Configurable]] field of current is false.
            if (!current.configurable())
                return reject(exec, throwException, "Attempting to change access mechanism for an unconfigurable property.");
            // 9.b. If IsDataDescriptor(current) is true, then convert the property named P of object O from a
            // data property to an accessor property. Preserve the existing values of the converted property‘s
            // [[Configurable]] and [[Enumerable]] attributes and set the rest of the property‘s attributes to
            // their default values.
            // 9.c. Else, convert the property named P of object O from an accessor property to a data property.
            // Preserve the existing values of the converted property‘s [[Configurable]] and [[Enumerable]]
            // attributes and set the rest of the property‘s attributes to their default values.
        } else if (current.isDataDescriptor() && descriptor.isDataDescriptor()) {
            // 10. Else, if IsDataDescriptor(current) and IsDataDescriptor(Desc) are both true, then
            // 10.a. If the [[Configurable]] field of current is false, then
            if (!current.configurable() && !current.writable()) {
                // 10.a.i. Reject, if the [[Writable]] field of current is false and the [[Writable]] field of Desc is true.
                if (descriptor.writable())
                    return reject(exec, throwException, "Attempting to change writable attribute of unconfigurable property.");
                // 10.a.ii. If the [[Writable]] field of current is false, then
                // 10.a.ii.1. Reject, if the [[Value]] field of Desc is present and SameValue(Desc.[[Value]], current.[[Value]]) is false.
                if (descriptor.value() && !sameValue(exec, descriptor.value(), current.value()))
                    return reject(exec, throwException, "Attempting to change value of a readonly property.");
            }
            // 10.b. else, the [[Configurable]] field of current is true, so any change is acceptable.
        } else {
490
            ASSERT(current.isAccessorDescriptor() && current.getterPresent() && current.setterPresent());
491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530
            // 11. Else, IsAccessorDescriptor(current) and IsAccessorDescriptor(Desc) are both true so, if the [[Configurable]] field of current is false, then
            if (!current.configurable()) {
                // 11.i. Reject, if the [[Set]] field of Desc is present and SameValue(Desc.[[Set]], current.[[Set]]) is false.
                if (descriptor.setterPresent() && descriptor.setter() != current.setter())
                    return reject(exec, throwException, "Attempting to change the setter of an unconfigurable property.");
                // 11.ii. Reject, if the [[Get]] field of Desc is present and SameValue(Desc.[[Get]], current.[[Get]]) is false.
                if (descriptor.getterPresent() && descriptor.getter() != current.getter())
                    return reject(exec, throwException, "Attempting to change the getter of an unconfigurable property.");
            }
        }
    }

    // 12. For each attribute field of Desc that is present, set the correspondingly named attribute of the property named P of object O to the value of the field.
    putDescriptor(exec, entryInMap, descriptor, current);
    // 13. Return true.
    return true;
}

void JSArray::setLengthWritable(ExecState* exec, bool writable)
{
    ASSERT(isLengthWritable() || !writable);
    if (!isLengthWritable() || writable)
        return;

    enterSparseMode(exec->globalData());

    SparseArrayValueMap* map = m_storage->m_sparseValueMap;
    ASSERT(map);
    map->setLengthIsReadOnly();
}

// Defined in ES5.1 15.4.5.1
bool JSArray::defineOwnProperty(JSObject* object, ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor, bool throwException)
{
    JSArray* array = static_cast<JSArray*>(object);

    // 3. If P is "length", then
    if (propertyName == exec->propertyNames().length) {
        // All paths through length definition call the default [[DefineOwnProperty]], hence:
        // from ES5.1 8.12.9 7.a.
531
        if (descriptor.configurablePresent() && descriptor.configurable())
532 533
            return reject(exec, throwException, "Attempting to change configurable attribute of unconfigurable property.");
        // from ES5.1 8.12.9 7.b.
534
        if (descriptor.enumerablePresent() && descriptor.enumerable())
535 536 537 538 539 540 541
            return reject(exec, throwException, "Attempting to change enumerable attribute of unconfigurable property.");

        // a. If the [[Value]] field of Desc is absent, then
        // a.i. Return the result of calling the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length", Desc, and Throw as arguments.
        if (descriptor.isAccessorDescriptor())
            return reject(exec, throwException, "Attempting to change access mechanism for an unconfigurable property.");
        // from ES5.1 8.12.9 10.a.
542
        if (!array->isLengthWritable() && descriptor.writablePresent() && descriptor.writable())
543 544 545
            return reject(exec, throwException, "Attempting to change writable attribute of unconfigurable property.");
        // This descriptor is either just making length read-only, or changing nothing!
        if (!descriptor.value()) {
546 547
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
548 549 550 551 552 553 554 555 556 557 558 559 560 561
            return true;
        }
        
        // b. Let newLenDesc be a copy of Desc.
        // c. Let newLen be ToUint32(Desc.[[Value]]).
        unsigned newLen = descriptor.value().toUInt32(exec);
        // d. If newLen is not equal to ToNumber( Desc.[[Value]]), throw a RangeError exception.
        if (newLen != descriptor.value().toNumber(exec)) {
            throwError(exec, createRangeError(exec, "Invalid array length"));
            return false;
        }

        // Based on SameValue check in 8.12.9, this is always okay.
        if (newLen == array->length()) {
562 563
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584
            return true;
        }

        // e. Set newLenDesc.[[Value] to newLen.
        // f. If newLen >= oldLen, then
        // f.i. Return the result of calling the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length", newLenDesc, and Throw as arguments.
        // g. Reject if oldLenDesc.[[Writable]] is false.
        if (!array->isLengthWritable())
            return reject(exec, throwException, "Attempting to change value of a readonly property.");
        
        // h. If newLenDesc.[[Writable]] is absent or has the value true, let newWritable be true.
        // i. Else,
        // i.i. Need to defer setting the [[Writable]] attribute to false in case any elements cannot be deleted.
        // i.ii. Let newWritable be false.
        // i.iii. Set newLenDesc.[[Writable] to true.
        // j. Let succeeded be the result of calling the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length", newLenDesc, and Throw as arguments.
        // k. If succeeded is false, return false.
        // l. While newLen < oldLen repeat,
        // l.i. Set oldLen to oldLen – 1.
        // l.ii. Let deleteSucceeded be the result of calling the [[Delete]] internal method of A passing ToString(oldLen) and false as arguments.
        // l.iii. If deleteSucceeded is false, then
585
        if (!array->setLength(exec, newLen, throwException)) {
586 587 588 589
            // 1. Set newLenDesc.[[Value] to oldLen+1.
            // 2. If newWritable is false, set newLenDesc.[[Writable] to false.
            // 3. Call the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length", newLenDesc, and false as arguments.
            // 4. Reject.
590 591
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
592 593 594 595
            return false;
        }

        // m. If newWritable is false, then
596 597 598 599 600
        // i. Call the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length",
        //    Property Descriptor{[[Writable]]: false}, and false as arguments. This call will always
        //    return true.
        if (descriptor.writablePresent())
            array->setLengthWritable(exec, descriptor.writable());
601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624
        // n. Return true.
        return true;
    }

    // 4. Else if P is an array index (15.4), then
    bool isArrayIndex;
    // a. Let index be ToUint32(P).
    unsigned index = propertyName.toArrayIndex(isArrayIndex);
    if (isArrayIndex) {
        // b. Reject if index >= oldLen and oldLenDesc.[[Writable]] is false.
        if (index >= array->length() && !array->isLengthWritable())
            return reject(exec, throwException, "Attempting to define numeric property on array with non-writable length property.");
        // c. Let succeeded be the result of calling the default [[DefineOwnProperty]] internal method (8.12.9) on A passing P, Desc, and false as arguments.
        // d. Reject if succeeded is false.
        // e. If index >= oldLen
        // e.i. Set oldLenDesc.[[Value]] to index + 1.
        // e.ii. Call the default [[DefineOwnProperty]] internal method (8.12.9) on A passing "length", oldLenDesc, and false as arguments. This call will always return true.
        // f. Return true.
        return array->defineOwnNumericProperty(exec, index, descriptor, throwException);
    }

    return JSObject::defineOwnProperty(object, exec, propertyName, descriptor, throwException);
}

625
bool JSArray::getOwnPropertySlotByIndex(JSCell* cell, ExecState* exec, unsigned i, PropertySlot& slot)
626
{
627
    JSArray* thisObject = jsCast<JSArray*>(cell);
628
    ArrayStorage* storage = thisObject->m_storage;
629
    
ggaren@apple.com's avatar
ggaren@apple.com committed
630
    if (i >= storage->m_length) {
barraclough@apple.com's avatar
barraclough@apple.com committed
631
        if (i > MAX_ARRAY_INDEX)
632
            return thisObject->methodTable()->getOwnPropertySlot(thisObject, exec, Identifier::from(exec, i), slot);
darin's avatar
darin committed
633 634 635
        return false;
    }

636
    if (i < thisObject->m_vectorLength) {
637 638 639
        JSValue value = storage->m_vector[i].get();
        if (value) {
            slot.setValue(value);
darin's avatar
darin committed
640 641 642
            return true;
        }
    } else if (SparseArrayValueMap* map = storage->m_sparseValueMap) {
643 644
        SparseArrayValueMap::iterator it = map->find(i);
        if (it != map->notFound()) {
645
            it->second.get(slot);
646
            return true;
darin's avatar
darin committed
647 648 649
        }
    }

650
    return JSObject::getOwnPropertySlot(thisObject, exec, Identifier::from(exec, i), slot);
darin's avatar
darin committed
651 652
}

653 654
bool JSArray::getOwnPropertySlot(JSCell* cell, ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{
655
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
656
    if (propertyName == exec->propertyNames().length) {
657
        slot.setValue(jsNumber(thisObject->length()));
darin's avatar
darin committed
658 659 660 661
        return true;
    }

    bool isArrayIndex;
662
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
663
    if (isArrayIndex)
664
        return JSArray::getOwnPropertySlotByIndex(thisObject, exec, i, slot);
darin's avatar
darin committed
665

666
    return JSObject::getOwnPropertySlot(thisObject, exec, propertyName, slot);
darin's avatar
darin committed
667 668
}

669
bool JSArray::getOwnPropertyDescriptor(JSObject* object, ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
670
{
671
    JSArray* thisObject = jsCast<JSArray*>(object);
672
    if (propertyName == exec->propertyNames().length) {
673
        descriptor.setDescriptor(jsNumber(thisObject->length()), DontDelete | DontEnum);
674 675
        return true;
    }
676

677
    ArrayStorage* storage = thisObject->m_storage;
678 679
    
    bool isArrayIndex;
680
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
681
    if (isArrayIndex) {
682
        if (i >= storage->m_length)
683
            return false;
684
        if (i < thisObject->m_vectorLength) {
685
            WriteBarrier<Unknown>& value = storage->m_vector[i];
686
            if (value) {
687
                descriptor.setDescriptor(value.get(), 0);
688 689
                return true;
            }
690
        } else if (SparseArrayValueMap* map = storage->m_sparseValueMap) {
691 692
            SparseArrayValueMap::iterator it = map->find(i);
            if (it != map->notFound()) {
693
                it->second.get(descriptor);
694
                return true;
695 696 697
            }
        }
    }
698
    return JSObject::getOwnPropertyDescriptor(thisObject, exec, propertyName, descriptor);
699 700
}

701 702 703
// ECMA 15.4.5.1
void JSArray::put(JSCell* cell, ExecState* exec, const Identifier& propertyName, JSValue value, PutPropertySlot& slot)
{
704
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
705
    bool isArrayIndex;
706
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
707
    if (isArrayIndex) {
708
        putByIndex(thisObject, exec, i, value);
darin's avatar
darin committed
709 710 711 712
        return;
    }

    if (propertyName == exec->propertyNames().length) {
weinig@apple.com's avatar
weinig@apple.com committed
713 714
        unsigned newLength = value.toUInt32(exec);
        if (value.toNumber(exec) != static_cast<double>(newLength)) {
715
            throwError(exec, createRangeError(exec, "Invalid array length"));
darin's avatar
darin committed
716 717
            return;
        }
718
        thisObject->setLength(exec, newLength, slot.isStrictMode());
darin's avatar
darin committed
719 720 721
        return;
    }

722
    JSObject::put(thisObject, exec, propertyName, value, slot);
darin's avatar
darin committed
723 724
}

725
void JSArray::putByIndex(JSCell* cell, ExecState* exec, unsigned i, JSValue value)
726
{
727
    JSArray* thisObject = jsCast<JSArray*>(cell);
728 729 730
    thisObject->checkConsistency();

    ArrayStorage* storage = thisObject->m_storage;
731

732
    // Fast case - store to the vector.
733
    if (i < thisObject->m_vectorLength) {
734
        WriteBarrier<Unknown>& valueSlot = storage->m_vector[i];
735 736 737 738 739 740 741 742 743 744
        unsigned length = storage->m_length;

        // Update m_length & m_numValuesInVector as necessary.
        if (i >= length) {
            length = i + 1;
            storage->m_length = length;
            ++storage->m_numValuesInVector;
        } else if (!valueSlot)
            ++storage->m_numValuesInVector;

745 746
        valueSlot.set(exec->globalData(), thisObject, value);
        thisObject->checkConsistency();
darin's avatar
darin committed
747 748 749
        return;
    }

750 751 752 753 754 755 756 757
    // Handle 2^32-1 - this is not an array index (see ES5.1 15.4), and is treated as a regular property.
    if (UNLIKELY(i > MAX_ARRAY_INDEX)) {
        PutPropertySlot slot;
        thisObject->methodTable()->put(thisObject, exec, Identifier::from(exec, i), value, slot);
        return;
    }

    // For all other cases, call putByIndexBeyondVectorLength.
758
    thisObject->putByIndexBeyondVectorLength(exec, i, value);
759
    thisObject->checkConsistency();
760 761
}

762
NEVER_INLINE void JSArray::putByIndexBeyondVectorLength(ExecState* exec, unsigned i, JSValue value)
763
{
764 765
    JSGlobalData& globalData = exec->globalData();

766
    // i should be a valid array index that is outside of the current vector.
767
    ASSERT(i >= m_vectorLength);
768
    ASSERT(i <= MAX_ARRAY_INDEX);
769

770
    ArrayStorage* storage = m_storage;
darin's avatar
darin committed
771
    SparseArrayValueMap* map = storage->m_sparseValueMap;
ap@webkit.org's avatar
ap@webkit.org committed
772

773 774
    // First, handle cases where we don't currently have a sparse map.
    if (LIKELY(!map)) {
775 776 777 778
        // Update m_length if necessary.
        if (i >= storage->m_length)
            storage->m_length = i + 1;

779 780 781
        // Check that it is sensible to still be using a vector, and then try to grow the vector.
        if (LIKELY((isDenseEnoughForVector(i, storage->m_numValuesInVector)) && increaseVectorLength(i + 1))) {
            // success! - reread m_storage since it has likely been reallocated, and store to the vector.
782
            storage = m_storage;
783
            storage->m_vector[i].set(globalData, this, value);
784
            ++storage->m_numValuesInVector;
785
            return;
darin's avatar
darin committed
786
        }
787 788 789
        // We don't want to, or can't use a vector to hold this property - allocate a sparse map & add the value.
        map = new SparseArrayValueMap;
        storage->m_sparseValueMap = map;
790
        map->put(exec, this, i, value);
791
        return;
darin's avatar
darin committed
792 793
    }

794 795 796 797 798 799 800 801 802 803 804 805
    // Update m_length if necessary.
    unsigned length = storage->m_length;
    if (i >= length) {
        // Prohibit growing the array if length is not writable.
        if (map->lengthIsReadOnly()) {
            // FIXME: should throw in strict mode.
            return;
        }
        length = i + 1;
        storage->m_length = length;
    }

806 807 808 809
    // We are currently using a map - check whether we still want to be doing so.
    // We will continue  to use a sparse map if SparseMode is set, a vector would be too sparse, or if allocation fails.
    unsigned numValuesInArray = storage->m_numValuesInVector + map->size();
    if (map->sparseMode() || !isDenseEnoughForVector(length, numValuesInArray) || !increaseVectorLength(length)) {
810
        map->put(exec, this, i, value);
barraclough@apple.com's avatar
barraclough@apple.com committed
811 812
        return;
    }
darin's avatar
darin committed
813

814
    // Reread m_storage afterincreaseVectorLength, update m_numValuesInVector.
815
    storage = m_storage;
816
    storage->m_numValuesInVector = numValuesInArray;
817

818 819 820 821
    // Copy all values from the map into the vector, and delete the map.
    WriteBarrier<Unknown>* vector = storage->m_vector;
    SparseArrayValueMap::const_iterator end = map->end();
    for (SparseArrayValueMap::const_iterator it = map->begin(); it != end; ++it)
822
        vector[it->first].set(globalData, this, it->second.getNonSparseMode());
823 824 825 826 827 828 829 830
    delete map;
    storage->m_sparseValueMap = 0;

    // Store the new property into the vector.
    WriteBarrier<Unknown>& valueSlot = vector[i];
    if (!valueSlot)
        ++storage->m_numValuesInVector;
    valueSlot.set(globalData, this, value);
darin's avatar
darin committed
831 832
}

833 834
bool JSArray::deleteProperty(JSCell* cell, ExecState* exec, const Identifier& propertyName)
{
835
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
836
    bool isArrayIndex;
837
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
838
    if (isArrayIndex)
839
        return thisObject->methodTable()->deletePropertyByIndex(thisObject, exec, i);
darin's avatar
darin committed
840 841 842 843

    if (propertyName == exec->propertyNames().length)
        return false;

844
    return JSObject::deleteProperty(thisObject, exec, propertyName);
darin's avatar
darin committed
845 846
}

847
bool JSArray::deletePropertyByIndex(JSCell* cell, ExecState* exec, unsigned i)
848
{
849
    JSArray* thisObject = jsCast<JSArray*>(cell);
850 851
    thisObject->checkConsistency();

852 853 854
    if (i > MAX_ARRAY_INDEX)
        return thisObject->methodTable()->deleteProperty(thisObject, exec, Identifier::from(exec, i));

855
    ArrayStorage* storage = thisObject->m_storage;
856
    
857
    if (i < thisObject->m_vectorLength) {
858
        WriteBarrier<Unknown>& valueSlot = storage->m_vector[i];
859 860 861
        if (valueSlot) {
            valueSlot.clear();
            --storage->m_numValuesInVector;
862
        }
863
    } else if (SparseArrayValueMap* map = storage->m_sparseValueMap) {
864 865
        SparseArrayValueMap::iterator it = map->find(i);
        if (it != map->notFound()) {
866 867
            if (it->second.attributes & DontDelete)
                return false;
868
            map->remove(it);
darin's avatar
darin committed
869 870 871
        }
    }

872
    thisObject->checkConsistency();
873 874
    return true;
}
875

876 877
static int compareKeysForQSort(const void* a, const void* b)
{
878 879
    unsigned da = *static_cast<const unsigned*>(a);
    unsigned db = *static_cast<const unsigned*>(b);
880
    return (da > db) - (da < db);
darin's avatar
darin committed
881 882
}

883
void JSArray::getOwnPropertyNames(JSObject* object, ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
darin's avatar
darin committed
884
{
885
    JSArray* thisObject = jsCast<JSArray*>(object);
darin's avatar
darin committed
886
    // FIXME: Filling PropertyNameArray with an identifier for every integer
887 888
    // is incredibly inefficient for large arrays. We need a different approach,
    // which almost certainly means a different structure for PropertyNameArray.
darin's avatar
darin committed
889

890
    ArrayStorage* storage = thisObject->m_storage;
891
    
892
    unsigned usedVectorLength = min(storage->m_length, thisObject->m_vectorLength);
darin's avatar
darin committed
893
    for (unsigned i = 0; i < usedVectorLength; ++i) {
894
        if (storage->m_vector[i])
ap@webkit.org's avatar
ap@webkit.org committed
895
            propertyNames.add(Identifier::from(exec, i));
darin's avatar
darin committed
896 897 898
    }

    if (SparseArrayValueMap* map = storage->m_sparseValueMap) {
899
        Vector<unsigned> keys;
900 901
        keys.reserveCapacity(map->size());
        
902
        SparseArrayValueMap::const_iterator end = map->end();
903 904
        for (SparseArrayValueMap::const_iterator it = map->begin(); it != end; ++it) {
            if (mode == IncludeDontEnumProperties || !(it->second.attributes & DontEnum))
905
                keys.append(static_cast<unsigned>(it->first));
906 907
        }

908
        qsort(keys.begin(), keys.size(), sizeof(unsigned), compareKeysForQSort);
909
        for (unsigned i = 0; i < keys.size(); ++i)
910
            propertyNames.add(Identifier::from(exec, keys[i]));
darin's avatar
darin committed
911
    }
912

913 914 915
    if (mode == IncludeDontEnumProperties)
        propertyNames.add(exec->propertyNames().length);

916
    JSObject::getOwnPropertyNames(thisObject, exec, propertyNames, mode);
darin's avatar
darin committed
917 918
}

919 920 921 922 923
ALWAYS_INLINE unsigned JSArray::getNewVectorLength(unsigned desiredLength)
{
    ASSERT(desiredLength <= MAX_STORAGE_VECTOR_LENGTH);

    unsigned increasedLength;
924
    unsigned maxInitLength = min(m_storage->m_length, 100000U);
925

926 927
    if (desiredLength < maxInitLength)
        increasedLength = maxInitLength;
928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
    else if (!m_vectorLength)
        increasedLength = max(desiredLength, lastArraySize);
    else {
        // Mathematically equivalent to:
        //   increasedLength = (newLength * 3 + 1) / 2;
        // or:
        //   increasedLength = (unsigned)ceil(newLength * 1.5));
        // This form is not prone to internal overflow.
        increasedLength = desiredLength + (desiredLength >> 1) + (desiredLength & 1);
    }

    ASSERT(increasedLength >= desiredLength);

    lastArraySize = min(increasedLength, FIRST_VECTOR_GROW);

    return min(increasedLength, MAX_STORAGE_VECTOR_LENGTH);
}

darin@apple.com's avatar
darin@apple.com committed
946
bool JSArray::increaseVectorLength(unsigned newLength)
darin's avatar
darin committed
947
{
ap@webkit.org's avatar
ap@webkit.org committed
948 949
    // This function leaves the array in an internally inconsistent state, because it does not move any values from sparse value map
    // to the vector. Callers have to account for that, because they can do it more efficiently.
950 951
    if (newLength > MAX_STORAGE_VECTOR_LENGTH)
        return false;
ap@webkit.org's avatar
ap@webkit.org committed
952

953
    ArrayStorage* storage = m_storage;
darin's avatar
darin committed
954

955
    unsigned vectorLength = m_vectorLength;
darin's avatar
darin committed
956
    ASSERT(newLength > vectorLength);
957
    unsigned newVectorLength = getNewVectorLength(newLength);
958
    void* baseStorage = storage->m_allocBase;
darin's avatar
darin committed
959

960 961 962 963
    // Fast case - there is no precapacity. In these cases a realloc makes sense.
    if (LIKELY(!m_indexBias)) {
        if (!tryFastRealloc(baseStorage, storageSize(newVectorLength)).getValue(baseStorage))
            return false;
964

965 966
        storage = m_storage = reinterpret_cast_ptr<ArrayStorage*>(baseStorage);
        m_storage->m_allocBase = baseStorage;
967

968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990
        WriteBarrier<Unknown>* vector = storage->m_vector;
        for (unsigned i = vectorLength; i < newVectorLength; ++i)
            vector[i].clear();

        m_vectorLength = newVectorLength;
        
        Heap::heap(this)->reportExtraMemoryCost(storageSize(newVectorLength) - storageSize(vectorLength));
        return true;
    }

    // Remove some, but not all of the precapacity. Atomic decay, & capped to not overflow array length.
    unsigned newIndexBias = min(m_indexBias >> 1, MAX_STORAGE_VECTOR_LENGTH - newVectorLength);
    // Calculate new stoarge capcity, allowing room for the pre-capacity.
    unsigned newStorageCapacity = newVectorLength + newIndexBias;
    void* newAllocBase;
    if (!tryFastMalloc(storageSize(newStorageCapacity)).getValue(newAllocBase))
        return false;
    // The sum of m_vectorLength and m_indexBias will never exceed MAX_STORAGE_VECTOR_LENGTH.
    ASSERT(m_vectorLength <= MAX_STORAGE_VECTOR_LENGTH && (MAX_STORAGE_VECTOR_LENGTH - m_vectorLength) >= m_indexBias);
    unsigned currentCapacity = m_vectorLength + m_indexBias;
    // Currently there is no way to report to the heap that the extra capacity is shrinking!
    if (newStorageCapacity > currentCapacity)
        Heap::heap(this)->reportExtraMemoryCost((newStorageCapacity - currentCapacity) * sizeof(WriteBarrier<Unknown>));
ap@webkit.org's avatar
ap@webkit.org committed
991

992
    m_vectorLength = newVectorLength;
993 994 995 996 997 998 999 1000 1001 1002 1003
    m_indexBias = newIndexBias;
    m_storage = reinterpret_cast_ptr<ArrayStorage*>(reinterpret_cast<WriteBarrier<Unknown>*>(newAllocBase) + m_indexBias);

    // Copy the ArrayStorage header & current contents of the vector, clear the new post-capacity.
    memmove(m_storage, storage, storageSize(vectorLength));
    for (unsigned i = vectorLength; i < m_vectorLength; ++i)
        m_storage->m_vector[i].clear();

    // Free the old allocation, update m_allocBase.
    fastFree(m_storage->m_allocBase);
    m_storage->m_allocBase = newAllocBase;
darin's avatar
darin committed
1004

1005 1006
    return true;
}
darin's avatar
darin committed
1007

1008 1009
// This method makes room in the vector, but leaves the new space uncleared.
bool JSArray::unshiftCountSlowCase(unsigned count)
1010
{
1011 1012
    // If not, we should have handled this on the fast path.
    ASSERT(count > m_indexBias);
1013

1014
    ArrayStorage* storage = m_storage;
1015

1016 1017 1018 1019 1020 1021 1022 1023 1024