runtime/JSString.h

   1 /*
   2  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
   3  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
   4  *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Library General Public
   8  *  License as published by the Free Software Foundation; either
   9  *  version 2 of the License, or (at your option) any later version.
  10  *
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Library General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU Library General Public License
  17  *  along with this library; see the file COPYING.LIB.  If not, write to
  18  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19  *  Boston, MA 02110-1301, USA.
  20  *
  21  */
  22
  23 #ifndef JSString_h
  24 #define JSString_h
  25
  26 #include "CallFrame.h"
  27 #include "CommonIdentifiers.h"
  28 #include "Identifier.h"
  29 #include "JSNumberCell.h"
  30 #include "PropertyDescriptor.h"
  31 #include "PropertySlot.h"
  32 #include "RopeImpl.h"
  33
  34 namespace JSC {
  35
  36     class JSString;
  37
  38     JSString* jsEmptyString(JSGlobalData*);
  39     JSString* jsEmptyString(ExecState*);
  40     JSString* jsString(JSGlobalData*, const UString&); // returns empty string if passed null string
  41     JSString* jsString(ExecState*, const UString&); // returns empty string if passed null string
  42
  43     JSString* jsSingleCharacterString(JSGlobalData*, UChar);
  44     JSString* jsSingleCharacterString(ExecState*, UChar);
  45     JSString* jsSingleCharacterSubstring(ExecState*, const UString&, unsigned offset);
  46     JSString* jsSubstring(JSGlobalData*, const UString&, unsigned offset, unsigned length);
  47     JSString* jsSubstring(ExecState*, const UString&, unsigned offset, unsigned length);
  48
  49     // Non-trivial strings are two or more characters long.
  50     // These functions are faster than just calling jsString.
  51     JSString* jsNontrivialString(JSGlobalData*, const UString&);
  52     JSString* jsNontrivialString(ExecState*, const UString&);
  53     JSString* jsNontrivialString(JSGlobalData*, const char*);
  54     JSString* jsNontrivialString(ExecState*, const char*);
  55
  56     // Should be used for strings that are owned by an object that will
  57     // likely outlive the JSValue this makes, such as the parse tree or a
  58     // DOM object that contains a UString
  59     JSString* jsOwnedString(JSGlobalData*, const UString&);
  60     JSString* jsOwnedString(ExecState*, const UString&);
  61
  62     typedef void (*JSStringFinalizerCallback)(JSString*, void* context);
  63     JSString* jsStringWithFinalizer(ExecState*, const UString&, JSStringFinalizerCallback callback, void* context);
  64
  65     class JS_EXPORTCLASS JSString : public JSCell {
  66     public:
  67         friend class JIT;
  68         friend class JSGlobalData;
  69         friend class SpecializedThunkJIT;
  70         friend struct ThunkHelpers;
  71
  72         class RopeBuilder {
  73         public:
  74             RopeBuilder(unsigned fiberCount)
  75                 : m_index(0)
  76                 , m_rope(RopeImpl::tryCreateUninitialized(fiberCount))
  77             {
  78             }
  79
  80             bool isOutOfMemory() { return !m_rope; }
  81
  82             void append(RopeImpl::Fiber& fiber)
  83             {
  84                 ASSERT(m_rope);
  85                 m_rope->initializeFiber(m_index, fiber);
  86             }
  87             void append(const UString& string)
  88             {
  89                 ASSERT(m_rope);
  90                 m_rope->initializeFiber(m_index, string.rep());
  91             }
  92             void append(JSString* jsString)
  93             {
  94                 if (jsString->isRope()) {
  95                     for (unsigned i = 0; i < jsString->m_fiberCount; ++i)
  96                         append(jsString->m_other.m_fibers[i]);
  97                 } else
  98                     append(jsString->string());
  99             }
 100
 101             PassRefPtr<RopeImpl> release()
 102             {
 103                 ASSERT(m_index == m_rope->fiberCount());
 104                 return m_rope.release();
 105             }
 106
 107             unsigned length() { return m_rope->length(); }
 108
 109         private:
 110             unsigned m_index;
 111             RefPtr<RopeImpl> m_rope;
 112         };
 113
 114         class RopeIterator {
 115             public:
 116                 RopeIterator() { }
 117
 118                 RopeIterator(RopeImpl::Fiber* fibers, size_t fiberCount)
 119                 {
 120                     ASSERT(fiberCount);
 121                     m_workQueue.append(WorkItem(fibers, fiberCount));
 122                     skipRopes();
 123                 }
 124
 125                 RopeIterator& operator++()
 126                 {
 127                     WorkItem& item = m_workQueue.last();
 128                     ASSERT(!RopeImpl::isRope(item.fibers[item.i]));
 129                     if (++item.i == item.fiberCount)
 130                         m_workQueue.removeLast();
 131                     skipRopes();
 132                     return *this;
 133                 }
 134
 135                 UStringImpl* operator*()
 136                 {
 137                     WorkItem& item = m_workQueue.last();
 138                     RopeImpl::Fiber fiber = item.fibers[item.i];
 139                     ASSERT(!RopeImpl::isRope(fiber));
 140                     return static_cast<UStringImpl*>(fiber);
 141                 }
 142
 143                 bool operator!=(const RopeIterator& other) const
 144                 {
 145                     return m_workQueue != other.m_workQueue;
 146                 }
 147
 148             private:
 149                 struct WorkItem {
 150                     WorkItem(RopeImpl::Fiber* fibers, size_t fiberCount)
 151                         : fibers(fibers)
 152                         , fiberCount(fiberCount)
 153                         , i(0)
 154                     {
 155                     }
 156
 157                     bool operator!=(const WorkItem& other) const
 158                     {
 159                         return fibers != other.fibers || fiberCount != other.fiberCount || i != other.i;
 160                     }
 161
 162                     RopeImpl::Fiber* fibers;
 163                     size_t fiberCount;
 164                     size_t i;
 165                 };
 166
 167                 void skipRopes()
 168                 {
 169                     if (m_workQueue.isEmpty())
 170                         return;
 171
 172                     while (1) {
 173                         WorkItem& item = m_workQueue.last();
 174                         RopeImpl::Fiber fiber = item.fibers[item.i];
 175                         if (!RopeImpl::isRope(fiber))
 176                             break;
 177                         RopeImpl* rope = static_cast<RopeImpl*>(fiber);
 178                         if (++item.i == item.fiberCount)
 179                             m_workQueue.removeLast();
 180                         m_workQueue.append(WorkItem(rope->fibers(), rope->fiberCount()));
 181                     }
 182                 }
 183
 184                 Vector<WorkItem, 16> m_workQueue;
 185         };
 186
 187         ALWAYS_INLINE JSString(JSGlobalData* globalData, const UString& value)
 188             : JSCell(globalData->stringStructure.get())
 189             , m_length(value.size())
 190             , m_value(value)
 191             , m_fiberCount(0)
 192         {
 193             ASSERT(!m_value.isNull());
 194             Heap::heap(this)->reportExtraMemoryCost(value.cost());
 195         }
 196
 197         enum HasOtherOwnerType { HasOtherOwner };
 198         JSString(JSGlobalData* globalData, const UString& value, HasOtherOwnerType)
 199             : JSCell(globalData->stringStructure.get())
 200             , m_length(value.size())
 201             , m_value(value)
 202             , m_fiberCount(0)
 203         {
 204             ASSERT(!m_value.isNull());
 205         }
 206         JSString(JSGlobalData* globalData, PassRefPtr<UStringImpl> value, HasOtherOwnerType)
 207             : JSCell(globalData->stringStructure.get())
 208             , m_length(value->length())
 209             , m_value(value)
 210             , m_fiberCount(0)
 211         {
 212             ASSERT(!m_value.isNull());
 213         }
 214         JSString(JSGlobalData* globalData, PassRefPtr<RopeImpl> rope)
 215             : JSCell(globalData->stringStructure.get())
 216             , m_length(rope->length())
 217             , m_fiberCount(1)
 218         {
 219             m_other.m_fibers[0] = rope.releaseRef();
 220         }
 221         // This constructor constructs a new string by concatenating s1 & s2.
 222         // This should only be called with fiberCount <= 3.
 223         JSString(JSGlobalData* globalData, unsigned fiberCount, JSString* s1, JSString* s2)
 224             : JSCell(globalData->stringStructure.get())
 225             , m_length(s1->length() + s2->length())
 226             , m_fiberCount(fiberCount)
 227         {
 228             ASSERT(fiberCount <= s_maxInternalRopeLength);
 229             unsigned index = 0;
 230             appendStringInConstruct(index, s1);
 231             appendStringInConstruct(index, s2);
 232             ASSERT(fiberCount == index);
 233         }
 234         // This constructor constructs a new string by concatenating s1 & s2.
 235         // This should only be called with fiberCount <= 3.
 236         JSString(JSGlobalData* globalData, unsigned fiberCount, JSString* s1, const UString& u2)
 237             : JSCell(globalData->stringStructure.get())
 238             , m_length(s1->length() + u2.size())
 239             , m_fiberCount(fiberCount)
 240         {
 241             ASSERT(fiberCount <= s_maxInternalRopeLength);
 242             unsigned index = 0;
 243             appendStringInConstruct(index, s1);
 244             appendStringInConstruct(index, u2);
 245             ASSERT(fiberCount == index);
 246         }
 247         // This constructor constructs a new string by concatenating s1 & s2.
 248         // This should only be called with fiberCount <= 3.
 249         JSString(JSGlobalData* globalData, unsigned fiberCount, const UString& u1, JSString* s2)
 250             : JSCell(globalData->stringStructure.get())
 251             , m_length(u1.size() + s2->length())
 252             , m_fiberCount(fiberCount)
 253         {
 254             ASSERT(fiberCount <= s_maxInternalRopeLength);
 255             unsigned index = 0;
 256             appendStringInConstruct(index, u1);
 257             appendStringInConstruct(index, s2);
 258             ASSERT(fiberCount == index);
 259         }
 260         // This constructor constructs a new string by concatenating v1, v2 & v3.
 261         // This should only be called with fiberCount <= 3 ... which since every
 262         // value must require a fiberCount of at least one implies that the length
 263         // for each value must be exactly 1!
 264         JSString(ExecState* exec, JSValue v1, JSValue v2, JSValue v3)
 265             : JSCell(exec->globalData().stringStructure.get())
 266             , m_length(0)
 267             , m_fiberCount(s_maxInternalRopeLength)
 268         {
 269             unsigned index = 0;
 270             appendValueInConstructAndIncrementLength(exec, index, v1);
 271             appendValueInConstructAndIncrementLength(exec, index, v2);
 272             appendValueInConstructAndIncrementLength(exec, index, v3);
 273             ASSERT(index == s_maxInternalRopeLength);
 274         }
 275
 276         // This constructor constructs a new string by concatenating u1 & u2.
 277         JSString(JSGlobalData* globalData, const UString& u1, const UString& u2)
 278             : JSCell(globalData->stringStructure.get())
 279             , m_length(u1.size() + u2.size())
 280             , m_fiberCount(2)
 281         {
 282             unsigned index = 0;
 283             appendStringInConstruct(index, u1);
 284             appendStringInConstruct(index, u2);
 285             ASSERT(index <= s_maxInternalRopeLength);
 286         }
 287
 288         // This constructor constructs a new string by concatenating u1, u2 & u3.
 289         JSString(JSGlobalData* globalData, const UString& u1, const UString& u2, const UString& u3)
 290             : JSCell(globalData->stringStructure.get())
 291             , m_length(u1.size() + u2.size() + u3.size())
 292             , m_fiberCount(s_maxInternalRopeLength)
 293         {
 294             unsigned index = 0;
 295             appendStringInConstruct(index, u1);
 296             appendStringInConstruct(index, u2);
 297             appendStringInConstruct(index, u3);
 298             ASSERT(index <= s_maxInternalRopeLength);
 299         }
 300
 301         JSString(JSGlobalData* globalData, const UString& value, JSStringFinalizerCallback finalizer, void* context)
 302             : JSCell(globalData->stringStructure.get())
 303             , m_length(value.size())
 304             , m_value(value)
 305             , m_fiberCount(0)
 306         {
 307             ASSERT(!m_value.isNull());
 308             // nasty hack because we can't union non-POD types
 309             m_other.m_finalizerCallback = finalizer;
 310             m_other.m_finalizerContext = context;
 311             Heap::heap(this)->reportExtraMemoryCost(value.cost());
 312         }
 313
 314         ~JSString()
 315         {
 316             ASSERT(vptr() == JSGlobalData::jsStringVPtr);
 317             for (unsigned i = 0; i < m_fiberCount; ++i)
 318                 RopeImpl::deref(m_other.m_fibers[i]);
 319
 320             if (!m_fiberCount && m_other.m_finalizerCallback)
 321                 m_other.m_finalizerCallback(this, m_other.m_finalizerContext);
 322         }
 323
 324         const UString& value(ExecState* exec) const
 325         {
 326             if (isRope())
 327                 resolveRope(exec);
 328             return m_value;
 329         }
 330         const UString& tryGetValue() const
 331         {
 332             if (isRope())
 333                 resolveRope(0);
 334             return m_value;
 335         }
 336         unsigned length() { return m_length; }
 337
 338         bool getStringPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
 339         bool getStringPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
 340         bool getStringPropertyDescriptor(ExecState*, const Identifier& propertyName, PropertyDescriptor&);
 341
 342         bool canGetIndex(unsigned i) { return i < m_length; }
 343         JSString* getIndex(ExecState*, unsigned);
 344         JSString* getIndexSlowCase(ExecState*, unsigned);
 345
 346         JSValue replaceCharacter(ExecState*, UChar, const UString& replacement);
 347
 348         static PassRefPtr<Structure> createStructure(JSValue proto) { return Structure::create(proto, TypeInfo(StringType, OverridesGetOwnPropertySlot | NeedsThisConversion), AnonymousSlotCount); }
 349
 350     private:
 351         enum VPtrStealingHackType { VPtrStealingHack };
 352         JSString(VPtrStealingHackType)
 353             : JSCell(0)
 354             , m_fiberCount(0)
 355         {
 356         }
 357
 358         void resolveRope(ExecState*) const;
 359         JSString* substringFromRope(ExecState*, unsigned offset, unsigned length);
 360
 361         void appendStringInConstruct(unsigned& index, const UString& string)
 362         {
 363             UStringImpl* impl = string.rep();
 364             impl->ref();
 365             m_other.m_fibers[index++] = impl;
 366         }
 367
 368         void appendStringInConstruct(unsigned& index, JSString* jsString)
 369         {
 370             if (jsString->isRope()) {
 371                 for (unsigned i = 0; i < jsString->m_fiberCount; ++i) {
 372                     RopeImpl::Fiber fiber = jsString->m_other.m_fibers[i];
 373                     fiber->ref();
 374                     m_other.m_fibers[index++] = fiber;
 375                 }
 376             } else
 377                 appendStringInConstruct(index, jsString->string());
 378         }
 379
 380         void appendValueInConstructAndIncrementLength(ExecState* exec, unsigned& index, JSValue v)
 381         {
 382             if (v.isString()) {
 383                 ASSERT(asCell(v)->isString());
 384                 JSString* s = static_cast<JSString*>(asCell(v));
 385                 ASSERT(s->size() == 1);
 386                 appendStringInConstruct(index, s);
 387                 m_length += s->length();
 388             } else {
 389                 UString u(v.toString(exec));
 390                 UStringImpl* impl = u.rep();
 391                 impl->ref();
 392                 m_other.m_fibers[index++] = impl;
 393                 m_length += u.size();
 394             }
 395         }
 396
 397         virtual JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
 398         virtual bool getPrimitiveNumber(ExecState*, double& number, JSValue& value);
 399         virtual bool toBoolean(ExecState*) const;
 400         virtual double toNumber(ExecState*) const;
 401         virtual JSObject* toObject(ExecState*) const;
 402         virtual UString toString(ExecState*) const;
 403
 404         virtual JSObject* toThisObject(ExecState*) const;
 405
 406         // Actually getPropertySlot, not getOwnPropertySlot (see JSCell).
 407         virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
 408         virtual bool getOwnPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
 409         virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);
 410
 411         static const unsigned s_maxInternalRopeLength = 3;
 412
 413         // A string is represented either by a UString or a RopeImpl.
 414         unsigned m_length;
 415         mutable UString m_value;
 416         mutable unsigned m_fiberCount;
 417         // This structure exists to support a temporary workaround for a GC issue.
 418         struct JSStringFinalizerStruct {
 419             JSStringFinalizerStruct() : m_finalizerCallback(0) {}
 420             union {
 421                 mutable RopeImpl::Fiber m_fibers[s_maxInternalRopeLength];
 422                 struct {
 423                     JSStringFinalizerCallback m_finalizerCallback;
 424                     void* m_finalizerContext;
 425                 };
 426             };
 427         } m_other;
 428
 429         bool isRope() const { return m_fiberCount; }
 430         UString& string() { ASSERT(!isRope()); return m_value; }
 431         unsigned size() { return m_fiberCount ? m_fiberCount : 1; }
 432
 433         friend JSValue jsString(ExecState* exec, JSString* s1, JSString* s2);
 434         friend JSValue jsString(ExecState* exec, const UString& u1, JSString* s2);
 435         friend JSValue jsString(ExecState* exec, JSString* s1, const UString& u2);
 436         friend JSValue jsString(ExecState* exec, Register* strings, unsigned count);
 437         friend JSValue jsString(ExecState* exec, JSValue thisValue, const ArgList& args);
 438         friend JSString* jsStringWithFinalizer(ExecState*, const UString&, JSStringFinalizerCallback callback, void* context);
 439         friend JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length);
 440     };
 441
 442     JSString* asString(JSValue);
 443
 444     // When an object is created from a different DLL, MSVC changes vptr to a "local" one right after invoking a constructor,
 445     // see <http://groups.google.com/group/microsoft.public.vc.language/msg/55cdcefeaf770212>.
 446     // This breaks isJSString(), and we don't need that hack anyway, so we change vptr back to primary one.
 447     // The below function must be called by any inline function that invokes a JSString constructor.
 448 #if COMPILER(MSVC) && !defined(BUILDING_JavaScriptCore)
 449     inline JSString* fixupVPtr(JSGlobalData* globalData, JSString* string) { string->setVPtr(globalData->jsStringVPtr); return string; }
 450 #else
 451     inline JSString* fixupVPtr(JSGlobalData*, JSString* string) { return string; }
 452 #endif
 453
 454     inline JSString* asString(JSValue value)
 455     {
 456         ASSERT(asCell(value)->isString());
 457         return static_cast<JSString*>(asCell(value));
 458     }
 459
 460     inline JSString* jsEmptyString(JSGlobalData* globalData)
 461     {
 462         return globalData->smallStrings.emptyString(globalData);
 463     }
 464
 465     inline JSString* jsSingleCharacterString(JSGlobalData* globalData, UChar c)
 466     {
 467         if (c <= 0xFF)
 468             return globalData->smallStrings.singleCharacterString(globalData, c);
 469         return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(&c, 1)));
 470     }
 471
 472     inline JSString* jsSingleCharacterSubstring(ExecState* exec, const UString& s, unsigned offset)
 473     {
 474         JSGlobalData* globalData = &exec->globalData();
 475         ASSERT(offset < static_cast<unsigned>(s.size()));
 476         UChar c = s.data()[offset];
 477         if (c <= 0xFF)
 478             return globalData->smallStrings.singleCharacterString(globalData, c);
 479         return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(UStringImpl::create(s.rep(), offset, 1))));
 480     }
 481
 482     inline JSString* jsNontrivialString(JSGlobalData* globalData, const char* s)
 483     {
 484         ASSERT(s);
 485         ASSERT(s[0]);
 486         ASSERT(s[1]);
 487         return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
 488     }
 489
 490     inline JSString* jsNontrivialString(JSGlobalData* globalData, const UString& s)
 491     {
 492         ASSERT(s.size() > 1);
 493         return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
 494     }
 495
 496     inline JSString* JSString::getIndex(ExecState* exec, unsigned i)
 497     {
 498         ASSERT(canGetIndex(i));
 499         if (isRope())
 500             return getIndexSlowCase(exec, i);
 501         ASSERT(i < m_value.size());
 502         return jsSingleCharacterSubstring(exec, m_value, i);
 503     }
 504
 505     inline JSString* jsString(JSGlobalData* globalData, const UString& s)
 506     {
 507         int size = s.size();
 508         if (!size)
 509             return globalData->smallStrings.emptyString(globalData);
 510         if (size == 1) {
 511             UChar c = s.data()[0];
 512             if (c <= 0xFF)
 513                 return globalData->smallStrings.singleCharacterString(globalData, c);
 514         }
 515         return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
 516     }
 517
 518     inline JSString* jsStringWithFinalizer(ExecState* exec, const UString& s, JSStringFinalizerCallback callback, void* context)
 519     {
 520         ASSERT(s.size() && (s.size() > 1 || s.data()[0] > 0xFF));
 521         JSGlobalData* globalData = &exec->globalData();
 522         return fixupVPtr(globalData, new (globalData) JSString(globalData, s, callback, context));
 523     }
 524
 525     inline JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length)
 526     {
 527         ASSERT(offset <= static_cast<unsigned>(s->length()));
 528         ASSERT(length <= static_cast<unsigned>(s->length()));
 529         ASSERT(offset + length <= static_cast<unsigned>(s->length()));
 530         JSGlobalData* globalData = &exec->globalData();
 531         if (!length)
 532             return globalData->smallStrings.emptyString(globalData);
 533         if (s->isRope())
 534             return s->substringFromRope(exec, offset, length);
 535         return jsSubstring(globalData, s->m_value, offset, length);
 536     }
 537
 538     inline JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
 539     {
 540         ASSERT(offset <= static_cast<unsigned>(s.size()));
 541         ASSERT(length <= static_cast<unsigned>(s.size()));
 542         ASSERT(offset + length <= static_cast<unsigned>(s.size()));
 543         if (!length)
 544             return globalData->smallStrings.emptyString(globalData);
 545         if (length == 1) {
 546             UChar c = s.data()[offset];
 547             if (c <= 0xFF)
 548                 return globalData->smallStrings.singleCharacterString(globalData, c);
 549         }
 550         return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(UStringImpl::create(s.rep(), offset, length)), JSString::HasOtherOwner));
 551     }
 552
 553     inline JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
 554     {
 555         int size = s.size();
 556         if (!size)
 557             return globalData->smallStrings.emptyString(globalData);
 558         if (size == 1) {
 559             UChar c = s.data()[0];
 560             if (c <= 0xFF)
 561                 return globalData->smallStrings.singleCharacterString(globalData, c);
 562         }
 563         return fixupVPtr(globalData, new (globalData) JSString(globalData, s, JSString::HasOtherOwner));
 564     }
 565
 566     inline JSString* jsEmptyString(ExecState* exec) { return jsEmptyString(&exec->globalData()); }
 567     inline JSString* jsString(ExecState* exec, const UString& s) { return jsString(&exec->globalData(), s); }
 568     inline JSString* jsSingleCharacterString(ExecState* exec, UChar c) { return jsSingleCharacterString(&exec->globalData(), c); }
 569     inline JSString* jsSubstring(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring(&exec->globalData(), s, offset, length); }
 570     inline JSString* jsNontrivialString(ExecState* exec, const UString& s) { return jsNontrivialString(&exec->globalData(), s); }
 571     inline JSString* jsNontrivialString(ExecState* exec, const char* s) { return jsNontrivialString(&exec->globalData(), s); }
 572     inline JSString* jsOwnedString(ExecState* exec, const UString& s) { return jsOwnedString(&exec->globalData(), s); }
 573
 574     ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
 575     {
 576         if (propertyName == exec->propertyNames().length) {
 577             slot.setValue(jsNumber(exec, m_length));
 578             return true;
 579         }
 580
 581         bool isStrictUInt32;
 582         unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);
 583         if (isStrictUInt32 && i < m_length) {
 584             slot.setValue(getIndex(exec, i));
 585             return true;
 586         }
 587
 588         return false;
 589     }
 590
 591     ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
 592     {
 593         if (propertyName < m_length) {
 594             slot.setValue(getIndex(exec, propertyName));
 595             return true;
 596         }
 597
 598         return false;
 599     }
 600
 601     inline bool isJSString(JSGlobalData* globalData, JSValue v) { return v.isCell() && v.asCell()->vptr() == globalData->jsStringVPtr; }
 602
 603     // --- JSValue inlines ----------------------------
 604
 605     inline UString JSValue::toString(ExecState* exec) const
 606     {
 607         if (isString())
 608             return static_cast<JSString*>(asCell())->value(exec);
 609         if (isInt32())
 610             return exec->globalData().numericStrings.add(asInt32());
 611         if (isDouble())
 612             return exec->globalData().numericStrings.add(asDouble());
 613         if (isTrue())
 614             return "true";
 615         if (isFalse())
 616             return "false";
 617         if (isNull())
 618             return "null";
 619         if (isUndefined())
 620             return "undefined";
 621         ASSERT(isCell());
 622         return asCell()->toString(exec);
 623     }
 624
 625     inline UString JSValue::toPrimitiveString(ExecState* exec) const
 626     {
 627         if (isString())
 628             return static_cast<JSString*>(asCell())->value(exec);
 629         if (isInt32())
 630             return exec->globalData().numericStrings.add(asInt32());
 631         if (isDouble())
 632             return exec->globalData().numericStrings.add(asDouble());
 633         if (isTrue())
 634             return "true";
 635         if (isFalse())
 636             return "false";
 637         if (isNull())
 638             return "null";
 639         if (isUndefined())
 640             return "undefined";
 641         ASSERT(isCell());
 642         return asCell()->toPrimitive(exec, NoPreference).toString(exec);
 643     }
 644
 645 } // namespace JSC
 646
 647 #endif // JSString_h