JSArray.cpp 72 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 28
#include "BumpSpace.h"
#include "BumpSpaceInlineMethods.h"
29
#include "CachedCall.h"
30
#include "Error.h"
31
#include "Executable.h"
32
#include "GetterSetter.h"
darin's avatar
darin committed
33
#include "PropertyNameArray.h"
ap@webkit.org's avatar
ap@webkit.org committed
34
#include <wtf/AVLTree.h>
35
#include <wtf/Assertions.h>
36
#include <wtf/OwnPtr.h>
37
#include <Operations.h>
darin's avatar
darin committed
38

39
using namespace std;
ap@webkit.org's avatar
ap@webkit.org committed
40
using namespace WTF;
bdash's avatar
bdash committed
41

42
namespace JSC {
darin's avatar
darin committed
43

ggaren@apple.com's avatar
ggaren@apple.com committed
44
ASSERT_CLASS_FITS_IN_CELL(JSArray);
45
ASSERT_HAS_TRIVIAL_DESTRUCTOR(JSArray);
ggaren@apple.com's avatar
ggaren@apple.com committed
46

barraclough@apple.com's avatar
barraclough@apple.com committed
47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
// 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:
//
64 65
//   * 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
66 67 68 69 70 71 72 73 74
//   * 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
75 76 77
// 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
78 79 80 81 82

// 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)
83
// 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
84
#define MAX_ARRAY_INDEX 0xFFFFFFFEU
darin's avatar
darin committed
85

86 87 88 89 90 91 92 93
// 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
94
// Our policy for when to use a vector and when to use a sparse map.
barraclough@apple.com's avatar
barraclough@apple.com committed
95 96
// 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
97 98 99
// as long as it is 1/8 full. If more sparse than that, we use a map.
static const unsigned minDensityMultiplier = 8;

100
const ClassInfo JSArray::s_info = {"Array", &JSNonFinalObject::s_info, 0, 0, CREATE_METHOD_TABLE(JSArray)};
darin's avatar
darin committed
101

102 103 104 105 106
// 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
107 108
static inline size_t storageSize(unsigned vectorLength)
{
barraclough@apple.com's avatar
barraclough@apple.com committed
109 110 111 112
    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.
113
    size_t size = (sizeof(ArrayStorage) - sizeof(WriteBarrier<Unknown>)) + (vectorLength * sizeof(WriteBarrier<Unknown>));
barraclough@apple.com's avatar
barraclough@apple.com committed
114 115
    // Assertion to detect integer overflow in previous calculation (should not be possible, provided that
    // MAX_STORAGE_VECTOR_LENGTH is correctly defined).
116
    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
117 118

    return size;
darin's avatar
darin committed
119 120 121 122
}

static inline bool isDenseEnoughForVector(unsigned length, unsigned numValues)
{
123
    return length <= MIN_SPARSE_ARRAY_INDEX || length / minDensityMultiplier <= numValues;
darin's avatar
darin committed
124 125
}

126 127
#if !CHECK_ARRAY_CONSISTENCY

darin@apple.com's avatar
darin@apple.com committed
128
inline void JSArray::checkConsistency(ConsistencyCheckType)
129 130 131 132 133
{
}

#endif

134 135
JSArray::JSArray(JSGlobalData& globalData, Structure* structure)
    : JSNonFinalObject(globalData, structure)
136
    , m_indexBias(0)
137
    , m_storage(0)
138 139
    , m_sparseValueMap(0)
    , m_subclassData(0)
weinig@apple.com's avatar
weinig@apple.com committed
140
{
141 142
}

143
void JSArray::finishCreation(JSGlobalData& globalData, unsigned initialLength)
144 145
{
    Base::finishCreation(globalData);
146 147
    ASSERT(inherits(&s_info));

148 149
    unsigned initialVectorLength = BASE_VECTOR_LEN;
    unsigned initialStorageSize = storageSize(initialVectorLength);
weinig@apple.com's avatar
weinig@apple.com committed
150

151 152 153 154 155
    void* newStorage = 0;
    if (!globalData.heap.tryAllocateStorage(initialStorageSize, &newStorage))
        CRASH();
    
    m_storage = static_cast<ArrayStorage*>(newStorage);
156
    m_storage->m_allocBase = m_storage;
157 158 159 160 161 162
    m_storage->m_length = initialLength;
    m_vectorLength = initialVectorLength;
    m_storage->m_numValuesInVector = 0;
#if CHECK_ARRAY_CONSISTENCY
    m_storage->m_inCompactInitialization = false;
#endif
weinig@apple.com's avatar
weinig@apple.com committed
163

164 165 166
    WriteBarrier<Unknown>* vector = m_storage->m_vector;
    for (size_t i = 0; i < initialVectorLength; ++i)
        vector[i].clear();
167

168
    checkConsistency();
weinig@apple.com's avatar
weinig@apple.com committed
169 170
}

171
JSArray* JSArray::tryFinishCreationUninitialized(JSGlobalData& globalData, unsigned initialLength)
darin's avatar
darin committed
172
{
173
    Base::finishCreation(globalData);
174 175
    ASSERT(inherits(&s_info));

176 177 178 179 180 181 182
    // 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);

183 184 185 186 187
    void* newStorage = 0;
    if (!globalData.heap.tryAllocateStorage(initialStorageSize, &newStorage))
        CRASH();
    
    m_storage = static_cast<ArrayStorage*>(newStorage);
188
    m_storage->m_allocBase = m_storage;
189 190 191
    m_storage->m_length = 0;
    m_vectorLength = initialVectorLength;
    m_storage->m_numValuesInVector = initialLength;
192

193
#if CHECK_ARRAY_CONSISTENCY
194
    m_storage->m_inCompactInitialization = true;
195
#endif
196

197 198 199 200 201
    WriteBarrier<Unknown>* vector = m_storage->m_vector;
    for (size_t i = initialLength; i < initialVectorLength; ++i)
        vector[i].clear();

    return this;
darin's avatar
darin committed
202 203
}

204 205
// This function can be called multiple times on the same object.
void JSArray::finalize(JSCell* cell)
darin's avatar
darin committed
206
{
207 208 209
    JSArray* thisObject = jsCast<JSArray*>(cell);
    thisObject->checkConsistency(DestructorConsistencyCheck);
    thisObject->deallocateSparseMap();
210 211
}

212
inline std::pair<SparseArrayValueMap::iterator, bool> SparseArrayValueMap::add(JSArray* array, unsigned i)
213
{
214 215 216 217 218 219 220 221
    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;
222 223
}

224
inline void SparseArrayValueMap::put(ExecState* exec, JSArray* array, unsigned i, JSValue value)
225
{
226 227 228
    // If the array is not extensible, we shouldn't get here!
    ASSERT(array->isExtensible());

229 230
    SparseArrayEntry& entry = add(array, i).first->second;

231
    if (!(entry.attributes & Accessor)) {
232 233 234 235 236 237 238
        if (entry.attributes & ReadOnly) {
            // FIXME: should throw if being called from strict mode.
            // throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
            return;
        }

        entry.set(exec->globalData(), array, value);
239
        return;
240
    }
241

242 243 244 245 246
    JSValue accessor = entry.Base::get();
    ASSERT(accessor.isGetterSetter());
    JSObject* setter = asGetterSetter(accessor)->setter();
    
    if (!setter) {
247 248
        // FIXME: should throw if being called from strict mode.
        // throwTypeError(exec, "setting a property that has only a getter");
249
        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
void JSArray::allocateSparseMap(JSGlobalData& globalData)
{
    m_sparseValueMap = new SparseArrayValueMap;
    globalData.heap.addFinalizer(this, finalize);
}

void JSArray::deallocateSparseMap()
{
    delete m_sparseValueMap;
    m_sparseValueMap = 0;
}

void JSArray::enterDictionaryMode(JSGlobalData& globalData)
326 327
{
    ArrayStorage* storage = m_storage;
328
    SparseArrayValueMap* map = m_sparseValueMap;
329

330 331 332 333
    if (!map) {
        allocateSparseMap(globalData);
        map = m_sparseValueMap;
    }
334 335 336 337 338 339 340 341 342 343 344 345 346 347 348

    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);
    }

349 350 351 352 353
    void* newRawStorage = 0;
    if (!globalData.heap.tryAllocateStorage(storageSize(0), &newRawStorage))
        CRASH();
    
    ArrayStorage* newStorage = static_cast<ArrayStorage*>(newRawStorage);
354 355 356 357 358 359 360 361 362 363 364 365
    memcpy(newStorage, m_storage, storageSize(0));
    newStorage->m_allocBase = newStorage;
    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());
366 367
        else if (oldDescriptor.isAccessorDescriptor())
            entryInMap->set(exec->globalData(), this, jsUndefined());
368
        entryInMap->attributes = descriptor.attributesOverridingCurrent(oldDescriptor) & ~Accessor;
369 370 371 372 373
        return;
    }

    if (descriptor.isAccessorDescriptor()) {
        JSObject* getter = 0;
374 375 376 377
        if (descriptor.getterPresent())
            getter = descriptor.getterObject();
        else if (oldDescriptor.isAccessorDescriptor())
            getter = oldDescriptor.getterObject();
378
        JSObject* setter = 0;
379 380 381 382
        if (descriptor.setterPresent())
            setter = descriptor.setterObject();
        else if (oldDescriptor.isAccessorDescriptor())
            setter = oldDescriptor.setterObject();
383 384 385 386 387 388 389 390

        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);
391
        entryInMap->attributes = descriptor.attributesOverridingCurrent(oldDescriptor) & ~ReadOnly;
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
        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;
        }

422
        enterDictionaryMode(exec->globalData());
423 424
    }

425
    SparseArrayValueMap* map = m_sparseValueMap;
426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471
    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.
472
        if (descriptor.configurablePresent() && descriptor.configurable())
473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506
            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 {
507
            ASSERT(current.isAccessorDescriptor() && current.getterPresent() && current.setterPresent());
508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
            // 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;

532
    enterDictionaryMode(exec->globalData());
533

534
    SparseArrayValueMap* map = m_sparseValueMap;
535 536 537 538 539 540 541 542 543 544 545 546 547
    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.
548
        if (descriptor.configurablePresent() && descriptor.configurable())
549 550
            return reject(exec, throwException, "Attempting to change configurable attribute of unconfigurable property.");
        // from ES5.1 8.12.9 7.b.
551
        if (descriptor.enumerablePresent() && descriptor.enumerable())
552 553 554 555 556 557 558
            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.
559
        if (!array->isLengthWritable() && descriptor.writablePresent() && descriptor.writable())
560 561 562
            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()) {
563 564
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
565 566 567 568 569 570 571 572 573 574 575 576 577 578
            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()) {
579 580
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601
            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
602
        if (!array->setLength(exec, newLen, throwException)) {
603 604 605 606
            // 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.
607 608
            if (descriptor.writablePresent())
                array->setLengthWritable(exec, descriptor.writable());
609 610 611 612
            return false;
        }

        // m. If newWritable is false, then
613 614 615 616 617
        // 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());
618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641
        // 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);
}

642
bool JSArray::getOwnPropertySlotByIndex(JSCell* cell, ExecState* exec, unsigned i, PropertySlot& slot)
643
{
644
    JSArray* thisObject = jsCast<JSArray*>(cell);
645
    ArrayStorage* storage = thisObject->m_storage;
646

ggaren@apple.com's avatar
ggaren@apple.com committed
647
    if (i >= storage->m_length) {
barraclough@apple.com's avatar
barraclough@apple.com committed
648
        if (i > MAX_ARRAY_INDEX)
649
            return thisObject->methodTable()->getOwnPropertySlot(thisObject, exec, Identifier::from(exec, i), slot);
darin's avatar
darin committed
650 651 652
        return false;
    }

653
    if (i < thisObject->m_vectorLength) {
654 655 656
        JSValue value = storage->m_vector[i].get();
        if (value) {
            slot.setValue(value);
darin's avatar
darin committed
657 658
            return true;
        }
659
    } else if (SparseArrayValueMap* map = thisObject->m_sparseValueMap) {
660 661
        SparseArrayValueMap::iterator it = map->find(i);
        if (it != map->notFound()) {
662
            it->second.get(slot);
663
            return true;
darin's avatar
darin committed
664 665 666
        }
    }

667
    return JSObject::getOwnPropertySlot(thisObject, exec, Identifier::from(exec, i), slot);
darin's avatar
darin committed
668 669
}

670 671
bool JSArray::getOwnPropertySlot(JSCell* cell, ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{
672
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
673
    if (propertyName == exec->propertyNames().length) {
674
        slot.setValue(jsNumber(thisObject->length()));
darin's avatar
darin committed
675 676 677 678
        return true;
    }

    bool isArrayIndex;
679
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
680
    if (isArrayIndex)
681
        return JSArray::getOwnPropertySlotByIndex(thisObject, exec, i, slot);
darin's avatar
darin committed
682

683
    return JSObject::getOwnPropertySlot(thisObject, exec, propertyName, slot);
darin's avatar
darin committed
684 685
}

686
bool JSArray::getOwnPropertyDescriptor(JSObject* object, ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
687
{
688
    JSArray* thisObject = jsCast<JSArray*>(object);
689
    if (propertyName == exec->propertyNames().length) {
690
        descriptor.setDescriptor(jsNumber(thisObject->length()), DontDelete | DontEnum);
691 692
        return true;
    }
693

694
    ArrayStorage* storage = thisObject->m_storage;
695 696
    
    bool isArrayIndex;
697
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
698
    if (isArrayIndex) {
699
        if (i >= storage->m_length)
700
            return false;
701
        if (i < thisObject->m_vectorLength) {
702
            WriteBarrier<Unknown>& value = storage->m_vector[i];
703
            if (value) {
704
                descriptor.setDescriptor(value.get(), 0);
705 706
                return true;
            }
707
        } else if (SparseArrayValueMap* map = thisObject->m_sparseValueMap) {
708 709
            SparseArrayValueMap::iterator it = map->find(i);
            if (it != map->notFound()) {
710
                it->second.get(descriptor);
711
                return true;
712 713 714
            }
        }
    }
715
    return JSObject::getOwnPropertyDescriptor(thisObject, exec, propertyName, descriptor);
716 717
}

718 719 720
// ECMA 15.4.5.1
void JSArray::put(JSCell* cell, ExecState* exec, const Identifier& propertyName, JSValue value, PutPropertySlot& slot)
{
721
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
722
    bool isArrayIndex;
723
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
724
    if (isArrayIndex) {
725
        putByIndex(thisObject, exec, i, value);
darin's avatar
darin committed
726 727 728 729
        return;
    }

    if (propertyName == exec->propertyNames().length) {
weinig@apple.com's avatar
weinig@apple.com committed
730 731
        unsigned newLength = value.toUInt32(exec);
        if (value.toNumber(exec) != static_cast<double>(newLength)) {
732
            throwError(exec, createRangeError(exec, "Invalid array length"));
darin's avatar
darin committed
733 734
            return;
        }
735
        thisObject->setLength(exec, newLength, slot.isStrictMode());
darin's avatar
darin committed
736 737 738
        return;
    }

739
    JSObject::put(thisObject, exec, propertyName, value, slot);
darin's avatar
darin committed
740 741
}

742
void JSArray::putByIndex(JSCell* cell, ExecState* exec, unsigned i, JSValue value)
743
{
744
    JSArray* thisObject = jsCast<JSArray*>(cell);
745 746 747
    thisObject->checkConsistency();

    ArrayStorage* storage = thisObject->m_storage;
748

749
    // Fast case - store to the vector.
750
    if (i < thisObject->m_vectorLength) {
751
        WriteBarrier<Unknown>& valueSlot = storage->m_vector[i];
752 753 754 755 756 757 758 759 760 761
        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;

762 763
        valueSlot.set(exec->globalData(), thisObject, value);
        thisObject->checkConsistency();
darin's avatar
darin committed
764 765 766
        return;
    }

767 768 769 770 771 772 773 774
    // 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.
775
    thisObject->putByIndexBeyondVectorLength(exec, i, value);
776
    thisObject->checkConsistency();
777 778
}

779
NEVER_INLINE void JSArray::putByIndexBeyondVectorLength(ExecState* exec, unsigned i, JSValue value)
780
{
781 782
    JSGlobalData& globalData = exec->globalData();

783
    // i should be a valid array index that is outside of the current vector.
784
    ASSERT(i >= m_vectorLength);
785
    ASSERT(i <= MAX_ARRAY_INDEX);
786

787
    ArrayStorage* storage = m_storage;
788
    SparseArrayValueMap* map = m_sparseValueMap;
ap@webkit.org's avatar
ap@webkit.org committed
789

790 791
    // First, handle cases where we don't currently have a sparse map.
    if (LIKELY(!map)) {
792 793 794
        // If the array is not extensible, we should have entered dictionary mode, and created the spare map.
        ASSERT(isExtensible());
    
795 796 797 798
        // Update m_length if necessary.
        if (i >= storage->m_length)
            storage->m_length = i + 1;

799
        // Check that it is sensible to still be using a vector, and then try to grow the vector.
800
        if (LIKELY((isDenseEnoughForVector(i, storage->m_numValuesInVector)) && increaseVectorLength(globalData, i + 1))) {
801
            // success! - reread m_storage since it has likely been reallocated, and store to the vector.
802
            storage = m_storage;
803
            storage->m_vector[i].set(globalData, this, value);
804
            ++storage->m_numValuesInVector;
805
            return;
darin's avatar
darin committed
806
        }
807
        // We don't want to, or can't use a vector to hold this property - allocate a sparse map & add the value.
808 809
        allocateSparseMap(exec->globalData());
        map = m_sparseValueMap;
810
        map->put(exec, this, i, value);
811
        return;
darin's avatar
darin committed
812 813
    }

814 815 816 817
    // Update m_length if necessary.
    unsigned length = storage->m_length;
    if (i >= length) {
        // Prohibit growing the array if length is not writable.
818
        if (map->lengthIsReadOnly() || !isExtensible()) {
819 820 821 822 823 824 825
            // FIXME: should throw in strict mode.
            return;
        }
        length = i + 1;
        storage->m_length = length;
    }

826 827 828
    // 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();
829
    if (map->sparseMode() || !isDenseEnoughForVector(length, numValuesInArray) || !increaseVectorLength(exec->globalData(), length)) {
830
        map->put(exec, this, i, value);
barraclough@apple.com's avatar
barraclough@apple.com committed
831 832
        return;
    }
darin's avatar
darin committed
833

834
    // Reread m_storage afterincreaseVectorLength, update m_numValuesInVector.
835
    storage = m_storage;
836
    storage->m_numValuesInVector = numValuesInArray;
837

838 839 840 841
    // 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)
842
        vector[it->first].set(globalData, this, it->second.getNonSparseMode());
843
    deallocateSparseMap();
844 845 846 847 848 849

    // 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
850 851
}

852 853
bool JSArray::deleteProperty(JSCell* cell, ExecState* exec, const Identifier& propertyName)
{
854
    JSArray* thisObject = jsCast<JSArray*>(cell);
darin's avatar
darin committed
855
    bool isArrayIndex;
856
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
darin's avatar
darin committed
857
    if (isArrayIndex)
858
        return thisObject->methodTable()->deletePropertyByIndex(thisObject, exec, i);
darin's avatar
darin committed
859 860 861 862

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

863
    return JSObject::deleteProperty(thisObject, exec, propertyName);
darin's avatar
darin committed
864 865
}

866
bool JSArray::deletePropertyByIndex(JSCell* cell, ExecState* exec, unsigned i)
867
{
868
    JSArray* thisObject = jsCast<JSArray*>(cell);
869 870
    thisObject->checkConsistency();

871 872 873
    if (i > MAX_ARRAY_INDEX)
        return thisObject->methodTable()->deleteProperty(thisObject, exec, Identifier::from(exec, i));

874
    ArrayStorage* storage = thisObject->m_storage;
875
    
876
    if (i < thisObject->m_vectorLength) {
877
        WriteBarrier<Unknown>& valueSlot = storage->m_vector[i];
878 879 880
        if (valueSlot) {
            valueSlot.clear();
            --storage->m_numValuesInVector;
881
        }
882
    } else if (SparseArrayValueMap* map = thisObject->m_sparseValueMap) {
883 884
        SparseArrayValueMap::iterator it = map->find(i);
        if (it != map->notFound()) {
885 886
            if (it->second.attributes & DontDelete)
                return false;
887
            map->remove(it);
darin's avatar
darin committed
888 889 890
        }
    }

891
    thisObject->checkConsistency();
892 893
    return true;
}
894

895 896
static int compareKeysForQSort(const void* a, const void* b)
{
897 898
    unsigned da = *static_cast<const unsigned*>(a);
    unsigned db = *static_cast<const unsigned*>(b);
899
    return (da > db) - (da < db);
darin's avatar
darin committed
900 901
}

902
void JSArray::getOwnPropertyNames(JSObject* object, ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
darin's avatar
darin committed
903
{
904
    JSArray* thisObject = jsCast<JSArray*>(object);
darin's avatar
darin committed
905
    // FIXME: Filling PropertyNameArray with an identifier for every integer
906 907
    // 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
908

909
    ArrayStorage* storage = thisObject->m_storage;
910
    
911
    unsigned usedVectorLength = min(storage->m_length, thisObject->m_vectorLength);
darin's avatar
darin committed
912
    for (unsigned i = 0; i < usedVectorLength; ++i) {
913
        if (storage->m_vector[i])
ap@webkit.org's avatar
ap@webkit.org committed
914
            propertyNames.add(Identifier::from(exec, i));
darin's avatar
darin committed
915 916
    }

917
    if (SparseArrayValueMap* map = thisObject->m_sparseValueMap) {
918
        Vector<unsigned> keys;
919 920
        keys.reserveCapacity(map->size());
        
921
        SparseArrayValueMap::const_iterator end = map->end();
922 923
        for (SparseArrayValueMap::const_iterator it = map->begin(); it != end; ++it) {
            if (mode == IncludeDontEnumProperties || !(it->second.attributes & DontEnum))
924
                keys.append(static_cast<unsigned>(it->first));
925 926
        }

927
        qsort(keys.begin(), keys.size(), sizeof(unsigned), compareKeysForQSort);
928
        for (unsigned i = 0; i < keys.size(); ++i)
929
            propertyNames.add(Identifier::from(exec, keys[i]));
darin's avatar
darin committed
930
    }
931

932 933 934
    if (mode == IncludeDontEnumProperties)
        propertyNames.add(exec->propertyNames().length);

935
    JSObject::getOwnPropertyNames(thisObject, exec, propertyNames, mode);
darin's avatar
darin committed
936 937
}

938 939 940 941 942
ALWAYS_INLINE unsigned JSArray::getNewVectorLength(unsigned desiredLength)
{
    ASSERT(desiredLength <= MAX_STORAGE_VECTOR_LENGTH);

    unsigned increasedLength;
943
    unsigned maxInitLength = min(m_storage->m_length, 100000U);
944

945 946
    if (desiredLength < maxInitLength)
        increasedLength = maxInitLength;
947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964
    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);
}

965
bool JSArray::increaseVectorLength(JSGlobalData& globalData, unsigned newLength)
darin's avatar
darin committed
966
{
ap@webkit.org's avatar
ap@webkit.org committed
967 968
    // 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.
969 970
    if (newLength > MAX_STORAGE_VECTOR_LENGTH)
        return false;
ap@webkit.org's avatar
ap@webkit.org committed
971

972
    ArrayStorage* storage = m_storage;
darin's avatar
darin committed
973

974
    unsigned vectorLength = m_vectorLength;
darin's avatar
darin committed
975
    ASSERT(newLength > vectorLength);
976
    unsigned newVectorLength = getNewVectorLength(newLength);
darin's avatar
darin committed
977

978 979
    // Fast case - there is no precapacity. In these cases a realloc makes sense.
    if (LIKELY(!m_indexBias)) {
980 981
        void* newStorage = storage->m_allocBase;
        if (!globalData.heap.tryReallocateStorage(&newStorage, storageSize(vectorLength), storageSize(newVectorLength)))
982
            return false;