runtime/JSONObject.cpp

   1 /*
   2  * Copyright (C) 2009 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "JSONObject.h"
  28
  29 #include "BooleanObject.h"
  30 #include "Error.h"
  31 #include "ExceptionHelpers.h"
  32 #include "JSArray.h"
  33 #include "JSGlobalObject.h"
  34 #include "LiteralParser.h"
  35 #include "Local.h"
  36 #include "LocalScope.h"
  37 #include "Lookup.h"
  38 #include "ObjectConstructor.h"
  39 #include "JSCInlines.h"
  40 #include "PropertyNameArray.h"
  41 #include <wtf/MathExtras.h>
  42 #include <wtf/text/StringBuilder.h>
  43
  44 namespace JSC {
  45
  46 STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(JSONObject);
  47
  48 static EncodedJSValue JSC_HOST_CALL JSONProtoFuncParse(ExecState*);
  49 static EncodedJSValue JSC_HOST_CALL JSONProtoFuncStringify(ExecState*);
  50
  51 }
  52
  53 #include "JSONObject.lut.h"
  54
  55 namespace JSC {
  56
  57 JSONObject::JSONObject(VM& vm, Structure* structure)
  58     : JSNonFinalObject(vm, structure)
  59 {
  60 }
  61
  62 void JSONObject::finishCreation(VM& vm)
  63 {
  64     Base::finishCreation(vm);
  65     ASSERT(inherits(info()));
  66 }
  67
  68 // PropertyNameForFunctionCall objects must be on the stack, since the JSValue that they create is not marked.
  69 class PropertyNameForFunctionCall {
  70 public:
  71     PropertyNameForFunctionCall(const Identifier&);
  72     PropertyNameForFunctionCall(unsigned);
  73
  74     JSValue value(ExecState*) const;
  75
  76 private:
  77     const Identifier* m_identifier;
  78     unsigned m_number;
  79     mutable JSValue m_value;
  80 };
  81
  82 class Stringifier {
  83     WTF_MAKE_NONCOPYABLE(Stringifier);
  84 public:
  85     Stringifier(ExecState*, const Local<Unknown>& replacer, const Local<Unknown>& space);
  86     Local<Unknown> stringify(Handle<Unknown>);
  87
  88     void visitAggregate(SlotVisitor&);
  89
  90 private:
  91     class Holder {
  92     public:
  93         Holder(VM&, JSObject*);
  94
  95         JSObject* object() const { return m_object.get(); }
  96
  97         bool appendNextProperty(Stringifier&, StringBuilder&);
  98
  99     private:
 100         Local<JSObject> m_object;
 101         const bool m_isArray;
 102         bool m_isJSArray;
 103         unsigned m_index;
 104         unsigned m_size;
 105         RefPtr<PropertyNameArrayData> m_propertyNames;
 106     };
 107
 108     friend class Holder;
 109
 110     static void appendQuotedString(StringBuilder&, const String&);
 111
 112     JSValue toJSON(JSValue, const PropertyNameForFunctionCall&);
 113
 114     enum StringifyResult { StringifyFailed, StringifySucceeded, StringifyFailedDueToUndefinedValue };
 115     StringifyResult appendStringifiedValue(StringBuilder&, JSValue, JSObject* holder, const PropertyNameForFunctionCall&);
 116
 117     bool willIndent() const;
 118     void indent();
 119     void unindent();
 120     void startNewLine(StringBuilder&) const;
 121
 122     ExecState* const m_exec;
 123     const Local<Unknown> m_replacer;
 124     bool m_usingArrayReplacer;
 125     PropertyNameArray m_arrayReplacerPropertyNames;
 126     CallType m_replacerCallType;
 127     CallData m_replacerCallData;
 128     const String m_gap;
 129
 130     Vector<Holder, 16, UnsafeVectorOverflow> m_holderStack;
 131     String m_repeatedGap;
 132     String m_indent;
 133 };
 134
 135 // ------------------------------ helper functions --------------------------------
 136
 137 static inline JSValue unwrapBoxedPrimitive(ExecState* exec, JSValue value)
 138 {
 139     if (!value.isObject())
 140         return value;
 141     JSObject* object = asObject(value);
 142     if (object->inherits(NumberObject::info()))
 143         return jsNumber(object->toNumber(exec));
 144     if (object->inherits(StringObject::info()))
 145         return object->toString(exec);
 146     if (object->inherits(BooleanObject::info()))
 147         return object->toPrimitive(exec);
 148     return value;
 149 }
 150
 151 static inline String gap(ExecState* exec, JSValue space)
 152 {
 153     const unsigned maxGapLength = 10;
 154     space = unwrapBoxedPrimitive(exec, space);
 155
 156     // If the space value is a number, create a gap string with that number of spaces.
 157     if (space.isNumber()) {
 158         double spaceCount = space.asNumber();
 159         int count;
 160         if (spaceCount > maxGapLength)
 161             count = maxGapLength;
 162         else if (!(spaceCount > 0))
 163             count = 0;
 164         else
 165             count = static_cast<int>(spaceCount);
 166         UChar spaces[maxGapLength];
 167         for (int i = 0; i < count; ++i)
 168             spaces[i] = ' ';
 169         return String(spaces, count);
 170     }
 171
 172     // If the space value is a string, use it as the gap string, otherwise use no gap string.
 173     String spaces = space.getString(exec);
 174     if (spaces.length() > maxGapLength) {
 175         spaces = spaces.substringSharingImpl(0, maxGapLength);
 176     }
 177     return spaces;
 178 }
 179
 180 // ------------------------------ PropertyNameForFunctionCall --------------------------------
 181
 182 inline PropertyNameForFunctionCall::PropertyNameForFunctionCall(const Identifier& identifier)
 183     : m_identifier(&identifier)
 184 {
 185 }
 186
 187 inline PropertyNameForFunctionCall::PropertyNameForFunctionCall(unsigned number)
 188     : m_identifier(0)
 189     , m_number(number)
 190 {
 191 }
 192
 193 JSValue PropertyNameForFunctionCall::value(ExecState* exec) const
 194 {
 195     if (!m_value) {
 196         if (m_identifier)
 197             m_value = jsString(exec, m_identifier->string());
 198         else
 199             m_value = jsNumber(m_number);
 200     }
 201     return m_value;
 202 }
 203
 204 // ------------------------------ Stringifier --------------------------------
 205
 206 Stringifier::Stringifier(ExecState* exec, const Local<Unknown>& replacer, const Local<Unknown>& space)
 207     : m_exec(exec)
 208     , m_replacer(replacer)
 209     , m_usingArrayReplacer(false)
 210     , m_arrayReplacerPropertyNames(exec)
 211     , m_replacerCallType(CallTypeNone)
 212     , m_gap(gap(exec, space.get()))
 213 {
 214     if (!m_replacer.isObject())
 215         return;
 216
 217     if (m_replacer.asObject()->inherits(JSArray::info())) {
 218         m_usingArrayReplacer = true;
 219         Handle<JSObject> array = m_replacer.asObject();
 220         unsigned length = array->get(exec, exec->vm().propertyNames->length).toUInt32(exec);
 221         for (unsigned i = 0; i < length; ++i) {
 222             JSValue name = array->get(exec, i);
 223             if (exec->hadException())
 224                 break;
 225
 226             if (name.isObject()) {
 227                 if (!asObject(name)->inherits(NumberObject::info()) && !asObject(name)->inherits(StringObject::info()))
 228                     continue;
 229             }
 230
 231             m_arrayReplacerPropertyNames.add(Identifier(exec, name.toString(exec)->value(exec)));
 232         }
 233         return;
 234     }
 235
 236     m_replacerCallType = m_replacer.asObject()->methodTable()->getCallData(m_replacer.asObject().get(), m_replacerCallData);
 237 }
 238
 239 Local<Unknown> Stringifier::stringify(Handle<Unknown> value)
 240 {
 241     JSObject* object = constructEmptyObject(m_exec);
 242     if (m_exec->hadException())
 243         return Local<Unknown>(m_exec->vm(), jsNull());
 244
 245     PropertyNameForFunctionCall emptyPropertyName(m_exec->vm().propertyNames->emptyIdentifier);
 246     object->putDirect(m_exec->vm(), m_exec->vm().propertyNames->emptyIdentifier, value.get());
 247
 248     StringBuilder result;
 249     if (appendStringifiedValue(result, value.get(), object, emptyPropertyName) != StringifySucceeded)
 250         return Local<Unknown>(m_exec->vm(), jsUndefined());
 251     if (m_exec->hadException())
 252         return Local<Unknown>(m_exec->vm(), jsNull());
 253
 254     return Local<Unknown>(m_exec->vm(), jsString(m_exec, result.toString()));
 255 }
 256
 257 template <typename CharType>
 258 static void appendStringToStringBuilder(StringBuilder& builder, const CharType* data, int length)
 259 {
 260     for (int i = 0; i < length; ++i) {
 261         int start = i;
 262         while (i < length && (data[i] > 0x1F && data[i] != '"' && data[i] != '\\'))
 263             ++i;
 264         builder.append(data + start, i - start);
 265         if (i >= length)
 266             break;
 267         switch (data[i]) {
 268         case '\t':
 269             builder.append('\\');
 270             builder.append('t');
 271             break;
 272         case '\r':
 273             builder.append('\\');
 274             builder.append('r');
 275             break;
 276         case '\n':
 277             builder.append('\\');
 278             builder.append('n');
 279             break;
 280         case '\f':
 281             builder.append('\\');
 282             builder.append('f');
 283             break;
 284         case '\b':
 285             builder.append('\\');
 286             builder.append('b');
 287             break;
 288         case '"':
 289             builder.append('\\');
 290             builder.append('"');
 291             break;
 292         case '\\':
 293             builder.append('\\');
 294             builder.append('\\');
 295             break;
 296         default:
 297             static const char hexDigits[] = "0123456789abcdef";
 298             UChar ch = data[i];
 299             LChar hex[] = { '\\', 'u', static_cast<LChar>(hexDigits[(ch >> 12) & 0xF]), static_cast<LChar>(hexDigits[(ch >> 8) & 0xF]), static_cast<LChar>(hexDigits[(ch >> 4) & 0xF]), static_cast<LChar>(hexDigits[ch & 0xF]) };
 300             builder.append(hex, WTF_ARRAY_LENGTH(hex));
 301             break;
 302         }
 303     }
 304 }
 305
 306 void escapeStringToBuilder(StringBuilder& builder, const String& message)
 307 {
 308     if (message.is8Bit())
 309         appendStringToStringBuilder(builder, message.characters8(), message.length());
 310     else
 311         appendStringToStringBuilder(builder, message.characters16(), message.length());
 312 }
 313
 314 void Stringifier::appendQuotedString(StringBuilder& builder, const String& value)
 315 {
 316     int length = value.length();
 317
 318     builder.append('"');
 319
 320     if (value.is8Bit())
 321         appendStringToStringBuilder<LChar>(builder, value.characters8(), length);
 322     else
 323         appendStringToStringBuilder<UChar>(builder, value.characters16(), length);
 324
 325     builder.append('"');
 326 }
 327
 328 inline JSValue Stringifier::toJSON(JSValue value, const PropertyNameForFunctionCall& propertyName)
 329 {
 330     ASSERT(!m_exec->hadException());
 331     if (!value.isObject() || !asObject(value)->hasProperty(m_exec, m_exec->vm().propertyNames->toJSON))
 332         return value;
 333
 334     JSValue toJSONFunction = asObject(value)->get(m_exec, m_exec->vm().propertyNames->toJSON);
 335     if (m_exec->hadException())
 336         return jsNull();
 337
 338     if (!toJSONFunction.isObject())
 339         return value;
 340
 341     JSObject* object = asObject(toJSONFunction);
 342     CallData callData;
 343     CallType callType = object->methodTable()->getCallData(object, callData);
 344     if (callType == CallTypeNone)
 345         return value;
 346
 347     MarkedArgumentBuffer args;
 348     args.append(propertyName.value(m_exec));
 349     return call(m_exec, object, callType, callData, value, args);
 350 }
 351
 352 Stringifier::StringifyResult Stringifier::appendStringifiedValue(StringBuilder& builder, JSValue value, JSObject* holder, const PropertyNameForFunctionCall& propertyName)
 353 {
 354     // Call the toJSON function.
 355     value = toJSON(value, propertyName);
 356     if (m_exec->hadException())
 357         return StringifyFailed;
 358
 359     // Call the replacer function.
 360     if (m_replacerCallType != CallTypeNone) {
 361         MarkedArgumentBuffer args;
 362         args.append(propertyName.value(m_exec));
 363         args.append(value);
 364         value = call(m_exec, m_replacer.get(), m_replacerCallType, m_replacerCallData, holder, args);
 365         if (m_exec->hadException())
 366             return StringifyFailed;
 367     }
 368
 369     if (value.isUndefined() && !holder->inherits(JSArray::info()))
 370         return StringifyFailedDueToUndefinedValue;
 371
 372     if (value.isNull()) {
 373         builder.appendLiteral("null");
 374         return StringifySucceeded;
 375     }
 376
 377     value = unwrapBoxedPrimitive(m_exec, value);
 378
 379     if (m_exec->hadException())
 380         return StringifyFailed;
 381
 382     if (value.isBoolean()) {
 383         if (value.isTrue())
 384             builder.appendLiteral("true");
 385         else
 386             builder.appendLiteral("false");
 387         return StringifySucceeded;
 388     }
 389
 390     String stringValue;
 391     if (value.getString(m_exec, stringValue)) {
 392         appendQuotedString(builder, stringValue);
 393         return StringifySucceeded;
 394     }
 395
 396     if (value.isNumber()) {
 397         double number = value.asNumber();
 398         if (!std::isfinite(number))
 399             builder.appendLiteral("null");
 400         else
 401             builder.append(String::numberToStringECMAScript(number));
 402         return StringifySucceeded;
 403     }
 404
 405     if (!value.isObject())
 406         return StringifyFailed;
 407
 408     JSObject* object = asObject(value);
 409
 410     CallData callData;
 411     if (object->methodTable()->getCallData(object, callData) != CallTypeNone) {
 412         if (holder->inherits(JSArray::info())) {
 413             builder.appendLiteral("null");
 414             return StringifySucceeded;
 415         }
 416         return StringifyFailedDueToUndefinedValue;
 417     }
 418
 419     // Handle cycle detection, and put the holder on the stack.
 420     for (unsigned i = 0; i < m_holderStack.size(); i++) {
 421         if (m_holderStack[i].object() == object) {
 422             m_exec->vm().throwException(m_exec, createTypeError(m_exec, ASCIILiteral("JSON.stringify cannot serialize cyclic structures.")));
 423             return StringifyFailed;
 424         }
 425     }
 426     bool holderStackWasEmpty = m_holderStack.isEmpty();
 427     m_holderStack.append(Holder(m_exec->vm(), object));
 428     if (!holderStackWasEmpty)
 429         return StringifySucceeded;
 430
 431     do {
 432         while (m_holderStack.last().appendNextProperty(*this, builder)) {
 433             if (m_exec->hadException())
 434                 return StringifyFailed;
 435         }
 436         m_holderStack.removeLast();
 437     } while (!m_holderStack.isEmpty());
 438     return StringifySucceeded;
 439 }
 440
 441 inline bool Stringifier::willIndent() const
 442 {
 443     return !m_gap.isEmpty();
 444 }
 445
 446 inline void Stringifier::indent()
 447 {
 448     // Use a single shared string, m_repeatedGap, so we don't keep allocating new ones as we indent and unindent.
 449     unsigned newSize = m_indent.length() + m_gap.length();
 450     if (newSize > m_repeatedGap.length())
 451         m_repeatedGap = makeString(m_repeatedGap, m_gap);
 452     ASSERT(newSize <= m_repeatedGap.length());
 453     m_indent = m_repeatedGap.substringSharingImpl(0, newSize);
 454 }
 455
 456 inline void Stringifier::unindent()
 457 {
 458     ASSERT(m_indent.length() >= m_gap.length());
 459     m_indent = m_repeatedGap.substringSharingImpl(0, m_indent.length() - m_gap.length());
 460 }
 461
 462 inline void Stringifier::startNewLine(StringBuilder& builder) const
 463 {
 464     if (m_gap.isEmpty())
 465         return;
 466     builder.append('\n');
 467     builder.append(m_indent);
 468 }
 469
 470 inline Stringifier::Holder::Holder(VM& vm, JSObject* object)
 471     : m_object(vm, object)
 472     , m_isArray(object->inherits(JSArray::info()))
 473     , m_index(0)
 474 #ifndef NDEBUG
 475     , m_size(0)
 476 #endif
 477 {
 478 }
 479
 480 bool Stringifier::Holder::appendNextProperty(Stringifier& stringifier, StringBuilder& builder)
 481 {
 482     ASSERT(m_index <= m_size);
 483
 484     ExecState* exec = stringifier.m_exec;
 485
 486     // First time through, initialize.
 487     if (!m_index) {
 488         if (m_isArray) {
 489             m_isJSArray = isJSArray(m_object.get());
 490             m_size = m_object->get(exec, exec->vm().propertyNames->length).toUInt32(exec);
 491             builder.append('[');
 492         } else {
 493             if (stringifier.m_usingArrayReplacer)
 494                 m_propertyNames = stringifier.m_arrayReplacerPropertyNames.data();
 495             else {
 496                 PropertyNameArray objectPropertyNames(exec);
 497                 m_object->methodTable()->getOwnPropertyNames(m_object.get(), exec, objectPropertyNames, ExcludeDontEnumProperties);
 498                 m_propertyNames = objectPropertyNames.releaseData();
 499             }
 500             m_size = m_propertyNames->propertyNameVector().size();
 501             builder.append('{');
 502         }
 503         stringifier.indent();
 504     }
 505
 506     // Last time through, finish up and return false.
 507     if (m_index == m_size) {
 508         stringifier.unindent();
 509         if (m_size && builder[builder.length() - 1] != '{')
 510             stringifier.startNewLine(builder);
 511         builder.append(m_isArray ? ']' : '}');
 512         return false;
 513     }
 514
 515     // Handle a single element of the array or object.
 516     unsigned index = m_index++;
 517     unsigned rollBackPoint = 0;
 518     StringifyResult stringifyResult;
 519     if (m_isArray) {
 520         // Get the value.
 521         JSValue value;
 522         if (m_isJSArray && asArray(m_object.get())->canGetIndexQuickly(index))
 523             value = asArray(m_object.get())->getIndexQuickly(index);
 524         else {
 525             PropertySlot slot(m_object.get());
 526             if (m_object->methodTable()->getOwnPropertySlotByIndex(m_object.get(), exec, index, slot)) {
 527                 value = slot.getValue(exec, index);
 528                 if (exec->hadException())
 529                     return false;
 530             } else
 531                 value = jsUndefined();
 532         }
 533
 534         // Append the separator string.
 535         if (index)
 536             builder.append(',');
 537         stringifier.startNewLine(builder);
 538
 539         // Append the stringified value.
 540         stringifyResult = stringifier.appendStringifiedValue(builder, value, m_object.get(), index);
 541     } else {
 542         // Get the value.
 543         PropertySlot slot(m_object.get());
 544         Identifier& propertyName = m_propertyNames->propertyNameVector()[index];
 545         if (!m_object->methodTable()->getOwnPropertySlot(m_object.get(), exec, propertyName, slot))
 546             return true;
 547         JSValue value = slot.getValue(exec, propertyName);
 548         if (exec->hadException())
 549             return false;
 550
 551         rollBackPoint = builder.length();
 552
 553         // Append the separator string.
 554         if (builder[rollBackPoint - 1] != '{')
 555             builder.append(',');
 556         stringifier.startNewLine(builder);
 557
 558         // Append the property name.
 559         appendQuotedString(builder, propertyName.string());
 560         builder.append(':');
 561         if (stringifier.willIndent())
 562             builder.append(' ');
 563
 564         // Append the stringified value.
 565         stringifyResult = stringifier.appendStringifiedValue(builder, value, m_object.get(), propertyName);
 566     }
 567
 568     // From this point on, no access to the this pointer or to any members, because the
 569     // Holder object may have moved if the call to stringify pushed a new Holder onto
 570     // m_holderStack.
 571
 572     switch (stringifyResult) {
 573         case StringifyFailed:
 574             builder.appendLiteral("null");
 575             break;
 576         case StringifySucceeded:
 577             break;
 578         case StringifyFailedDueToUndefinedValue:
 579             // This only occurs when get an undefined value for an object property.
 580             // In this case we don't want the separator and property name that we
 581             // already appended, so roll back.
 582             builder.resize(rollBackPoint);
 583             break;
 584     }
 585
 586     return true;
 587 }
 588
 589 // ------------------------------ JSONObject --------------------------------
 590
 591 const ClassInfo JSONObject::s_info = { "JSON", &JSNonFinalObject::s_info, 0, ExecState::jsonTable, CREATE_METHOD_TABLE(JSONObject) };
 592
 593 /* Source for JSONObject.lut.h
 594 @begin jsonTable
 595   parse         JSONProtoFuncParse             DontEnum|Function 2
 596   stringify     JSONProtoFuncStringify         DontEnum|Function 3
 597 @end
 598 */
 599
 600 // ECMA 15.8
 601
 602 bool JSONObject::getOwnPropertySlot(JSObject* object, ExecState* exec, PropertyName propertyName, PropertySlot& slot)
 603 {
 604     return getStaticFunctionSlot<JSObject>(exec, ExecState::jsonTable(exec->vm()), jsCast<JSONObject*>(object), propertyName, slot);
 605 }
 606
 607 class Walker {
 608 public:
 609     Walker(ExecState* exec, Handle<JSObject> function, CallType callType, CallData callData)
 610         : m_exec(exec)
 611         , m_function(exec->vm(), function)
 612         , m_callType(callType)
 613         , m_callData(callData)
 614     {
 615     }
 616     JSValue walk(JSValue unfiltered);
 617 private:
 618     JSValue callReviver(JSObject* thisObj, JSValue property, JSValue unfiltered)
 619     {
 620         MarkedArgumentBuffer args;
 621         args.append(property);
 622         args.append(unfiltered);
 623         return call(m_exec, m_function.get(), m_callType, m_callData, thisObj, args);
 624     }
 625
 626     friend class Holder;
 627
 628     ExecState* m_exec;
 629     Local<JSObject> m_function;
 630     CallType m_callType;
 631     CallData m_callData;
 632 };
 633
 634 // We clamp recursion well beyond anything reasonable.
 635 static const unsigned maximumFilterRecursion = 40000;
 636 enum WalkerState { StateUnknown, ArrayStartState, ArrayStartVisitMember, ArrayEndVisitMember,
 637                                  ObjectStartState, ObjectStartVisitMember, ObjectEndVisitMember };
 638 NEVER_INLINE JSValue Walker::walk(JSValue unfiltered)
 639 {
 640     Vector<PropertyNameArray, 16, UnsafeVectorOverflow> propertyStack;
 641     Vector<uint32_t, 16, UnsafeVectorOverflow> indexStack;
 642     LocalStack<JSObject, 16> objectStack(m_exec->vm());
 643     LocalStack<JSArray, 16> arrayStack(m_exec->vm());
 644
 645     Vector<WalkerState, 16, UnsafeVectorOverflow> stateStack;
 646     WalkerState state = StateUnknown;
 647     JSValue inValue = unfiltered;
 648     JSValue outValue = jsNull();
 649
 650     while (1) {
 651         switch (state) {
 652             arrayStartState:
 653             case ArrayStartState: {
 654                 ASSERT(inValue.isObject());
 655                 ASSERT(isJSArray(asObject(inValue)) || asObject(inValue)->inherits(JSArray::info()));
 656                 if (objectStack.size() + arrayStack.size() > maximumFilterRecursion)
 657                     return throwStackOverflowError(m_exec);
 658
 659                 JSArray* array = asArray(inValue);
 660                 arrayStack.push(array);
 661                 indexStack.append(0);
 662             }
 663             arrayStartVisitMember:
 664             FALLTHROUGH;
 665             case ArrayStartVisitMember: {
 666                 JSArray* array = arrayStack.peek();
 667                 uint32_t index = indexStack.last();
 668                 if (index == array->length()) {
 669                     outValue = array;
 670                     arrayStack.pop();
 671                     indexStack.removeLast();
 672                     break;
 673                 }
 674                 if (isJSArray(array) && array->canGetIndexQuickly(index))
 675                     inValue = array->getIndexQuickly(index);
 676                 else {
 677                     PropertySlot slot(array);
 678                     if (array->methodTable()->getOwnPropertySlotByIndex(array, m_exec, index, slot))
 679                         inValue = slot.getValue(m_exec, index);
 680                     else
 681                         inValue = jsUndefined();
 682                 }
 683
 684                 if (inValue.isObject()) {
 685                     stateStack.append(ArrayEndVisitMember);
 686                     goto stateUnknown;
 687                 } else
 688                     outValue = inValue;
 689                 FALLTHROUGH;
 690             }
 691             case ArrayEndVisitMember: {
 692                 JSArray* array = arrayStack.peek();
 693                 JSValue filteredValue = callReviver(array, jsString(m_exec, String::number(indexStack.last())), outValue);
 694                 if (filteredValue.isUndefined())
 695                     array->methodTable()->deletePropertyByIndex(array, m_exec, indexStack.last());
 696                 else
 697                     array->putDirectIndex(m_exec, indexStack.last(), filteredValue);
 698                 if (m_exec->hadException())
 699                     return jsNull();
 700                 indexStack.last()++;
 701                 goto arrayStartVisitMember;
 702             }
 703             objectStartState:
 704             case ObjectStartState: {
 705                 ASSERT(inValue.isObject());
 706                 ASSERT(!isJSArray(asObject(inValue)) && !asObject(inValue)->inherits(JSArray::info()));
 707                 if (objectStack.size() + arrayStack.size() > maximumFilterRecursion)
 708                     return throwStackOverflowError(m_exec);
 709
 710                 JSObject* object = asObject(inValue);
 711                 objectStack.push(object);
 712                 indexStack.append(0);
 713                 propertyStack.append(PropertyNameArray(m_exec));
 714                 object->methodTable()->getOwnPropertyNames(object, m_exec, propertyStack.last(), ExcludeDontEnumProperties);
 715             }
 716             objectStartVisitMember:
 717             FALLTHROUGH;
 718             case ObjectStartVisitMember: {
 719                 JSObject* object = objectStack.peek();
 720                 uint32_t index = indexStack.last();
 721                 PropertyNameArray& properties = propertyStack.last();
 722                 if (index == properties.size()) {
 723                     outValue = object;
 724                     objectStack.pop();
 725                     indexStack.removeLast();
 726                     propertyStack.removeLast();
 727                     break;
 728                 }
 729                 PropertySlot slot(object);
 730                 if (object->methodTable()->getOwnPropertySlot(object, m_exec, properties[index], slot))
 731                     inValue = slot.getValue(m_exec, properties[index]);
 732                 else
 733                     inValue = jsUndefined();
 734
 735                 // The holder may be modified by the reviver function so any lookup may throw
 736                 if (m_exec->hadException())
 737                     return jsNull();
 738
 739                 if (inValue.isObject()) {
 740                     stateStack.append(ObjectEndVisitMember);
 741                     goto stateUnknown;
 742                 } else
 743                     outValue = inValue;
 744                 FALLTHROUGH;
 745             }
 746             case ObjectEndVisitMember: {
 747                 JSObject* object = objectStack.peek();
 748                 Identifier prop = propertyStack.last()[indexStack.last()];
 749                 PutPropertySlot slot(object);
 750                 JSValue filteredValue = callReviver(object, jsString(m_exec, prop.string()), outValue);
 751                 if (filteredValue.isUndefined())
 752                     object->methodTable()->deleteProperty(object, m_exec, prop);
 753                 else
 754                     object->methodTable()->put(object, m_exec, prop, filteredValue, slot);
 755                 if (m_exec->hadException())
 756                     return jsNull();
 757                 indexStack.last()++;
 758                 goto objectStartVisitMember;
 759             }
 760             stateUnknown:
 761             case StateUnknown:
 762                 if (!inValue.isObject()) {
 763                     outValue = inValue;
 764                     break;
 765                 }
 766                 JSObject* object = asObject(inValue);
 767                 if (isJSArray(object) || object->inherits(JSArray::info()))
 768                     goto arrayStartState;
 769                 goto objectStartState;
 770         }
 771         if (stateStack.isEmpty())
 772             break;
 773
 774         state = stateStack.last();
 775         stateStack.removeLast();
 776     }
 777     JSObject* finalHolder = constructEmptyObject(m_exec);
 778     PutPropertySlot slot(finalHolder);
 779     finalHolder->methodTable()->put(finalHolder, m_exec, m_exec->vm().propertyNames->emptyIdentifier, outValue, slot);
 780     return callReviver(finalHolder, jsEmptyString(m_exec), outValue);
 781 }
 782
 783 // ECMA-262 v5 15.12.2
 784 EncodedJSValue JSC_HOST_CALL JSONProtoFuncParse(ExecState* exec)
 785 {
 786     if (!exec->argumentCount())
 787         return throwVMError(exec, createError(exec, ASCIILiteral("JSON.parse requires at least one parameter")));
 788     String source = exec->uncheckedArgument(0).toString(exec)->value(exec);
 789     if (exec->hadException())
 790         return JSValue::encode(jsNull());
 791
 792     JSValue unfiltered;
 793     LocalScope scope(exec->vm());
 794     if (source.is8Bit()) {
 795         LiteralParser<LChar> jsonParser(exec, source.characters8(), source.length(), StrictJSON);
 796         unfiltered = jsonParser.tryLiteralParse();
 797         if (!unfiltered)
 798             return throwVMError(exec, createSyntaxError(exec, jsonParser.getErrorMessage()));
 799     } else {
 800         LiteralParser<UChar> jsonParser(exec, source.characters16(), source.length(), StrictJSON);
 801         unfiltered = jsonParser.tryLiteralParse();
 802         if (!unfiltered)
 803             return throwVMError(exec, createSyntaxError(exec, jsonParser.getErrorMessage()));
 804     }
 805
 806     if (exec->argumentCount() < 2)
 807         return JSValue::encode(unfiltered);
 808
 809     JSValue function = exec->uncheckedArgument(1);
 810     CallData callData;
 811     CallType callType = getCallData(function, callData);
 812     if (callType == CallTypeNone)
 813         return JSValue::encode(unfiltered);
 814     return JSValue::encode(Walker(exec, Local<JSObject>(exec->vm(), asObject(function)), callType, callData).walk(unfiltered));
 815 }
 816
 817 // ECMA-262 v5 15.12.3
 818 EncodedJSValue JSC_HOST_CALL JSONProtoFuncStringify(ExecState* exec)
 819 {
 820     if (!exec->argumentCount())
 821         return throwVMError(exec, createError(exec, ASCIILiteral("No input to stringify")));
 822     LocalScope scope(exec->vm());
 823     Local<Unknown> value(exec->vm(), exec->uncheckedArgument(0));
 824     Local<Unknown> replacer(exec->vm(), exec->argument(1));
 825     Local<Unknown> space(exec->vm(), exec->argument(2));
 826     JSValue result = Stringifier(exec, replacer, space).stringify(value).get();
 827     return JSValue::encode(result);
 828 }
 829
 830 JSValue JSONParse(ExecState* exec, const String& json)
 831 {
 832     LocalScope scope(exec->vm());
 833
 834     if (json.is8Bit()) {
 835         LiteralParser<LChar> jsonParser(exec, json.characters8(), json.length(), StrictJSON);
 836         return jsonParser.tryLiteralParse();
 837     }
 838
 839     LiteralParser<UChar> jsonParser(exec, json.characters16(), json.length(), StrictJSON);
 840     return jsonParser.tryLiteralParse();
 841 }
 842
 843 String JSONStringify(ExecState* exec, JSValue value, unsigned indent)
 844 {
 845     LocalScope scope(exec->vm());
 846     Local<Unknown> result = Stringifier(exec, Local<Unknown>(exec->vm(), jsNull()), Local<Unknown>(exec->vm(), jsNumber(indent))).stringify(Local<Unknown>(exec->vm(), value));
 847     if (result.isUndefinedOrNull())
 848         return String();
 849     return result.getString(exec);
 850 }
 851
 852 } // namespace JSC