runtime/JSString.cpp

   1 /*
   2  *  Copyright (C) 1999-2002 Harri Porten (porten@kde.org)
   3  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
   4  *  Copyright (C) 2004, 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 #include "config.h"
  24 #include "JSString.h"
  25
  26 #include "JSGlobalObject.h"
  27 #include "JSGlobalObjectFunctions.h"
  28 #include "JSObject.h"
  29 #include "JSCInlines.h"
  30 #include "StringObject.h"
  31 #include "StringPrototype.h"
  32 #include "StrongInlines.h"
  33
  34 namespace JSC {
  35
  36 const ClassInfo JSString::s_info = { "string", 0, 0, CREATE_METHOD_TABLE(JSString) };
  37
  38 void JSRopeString::RopeBuilder::expand()
  39 {
  40     ASSERT(m_index == JSRopeString::s_maxInternalRopeLength);
  41     JSString* jsString = m_jsString;
  42     RELEASE_ASSERT(jsString);
  43     m_jsString = jsStringBuilder(&m_vm);
  44     m_index = 0;
  45     append(jsString);
  46 }
  47
  48 void JSString::destroy(JSCell* cell)
  49 {
  50     JSString* thisObject = static_cast<JSString*>(cell);
  51     thisObject->JSString::~JSString();
  52 }
  53
  54 void JSString::dumpToStream(const JSCell* cell, PrintStream& out)
  55 {
  56     const JSString* thisObject = jsCast<const JSString*>(cell);
  57     out.printf("<%p, %s, [%u], ", thisObject, thisObject->className(), thisObject->length());
  58     if (thisObject->isRope())
  59         out.printf("[rope]");
  60     else {
  61         WTF::StringImpl* ourImpl = thisObject->m_value.impl();
  62         if (ourImpl->is8Bit())
  63             out.printf("[8 %p]", ourImpl->characters8());
  64         else
  65             out.printf("[16 %p]", ourImpl->characters16());
  66     }
  67     out.printf(">");
  68 }
  69
  70 void JSString::visitChildren(JSCell* cell, SlotVisitor& visitor)
  71 {
  72     JSString* thisObject = jsCast<JSString*>(cell);
  73     Base::visitChildren(thisObject, visitor);
  74
  75     if (thisObject->isRope())
  76         static_cast<JSRopeString*>(thisObject)->visitFibers(visitor);
  77     else {
  78         StringImpl* impl = thisObject->m_value.impl();
  79         ASSERT(impl);
  80         visitor.reportExtraMemoryVisited(thisObject, impl->costDuringGC());
  81     }
  82 }
  83
  84 void JSRopeString::visitFibers(SlotVisitor& visitor)
  85 {
  86     if (isSubstring()) {
  87         visitor.append(&substringBase());
  88         return;
  89     }
  90     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i)
  91         visitor.append(&fiber(i));
  92 }
  93
  94 static const unsigned maxLengthForOnStackResolve = 2048;
  95
  96 void JSRopeString::resolveRopeInternal8(LChar* buffer) const
  97 {
  98     if (isSubstring()) {
  99         StringImpl::copyChars(
 100             buffer, substringBase()->m_value.characters8() + substringOffset(), m_length);
 101         return;
 102     }
 103
 104     resolveRopeInternal8NoSubstring(buffer);
 105 }
 106
 107 void JSRopeString::resolveRopeInternal8NoSubstring(LChar* buffer) const
 108 {
 109     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i) {
 110         if (fiber(i)->isRope()) {
 111             resolveRopeSlowCase8(buffer);
 112             return;
 113         }
 114     }
 115
 116     LChar* position = buffer;
 117     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i) {
 118         const StringImpl& fiberString = *fiber(i)->m_value.impl();
 119         unsigned length = fiberString.length();
 120         StringImpl::copyChars(position, fiberString.characters8(), length);
 121         position += length;
 122     }
 123     ASSERT((buffer + m_length) == position);
 124 }
 125
 126 void JSRopeString::resolveRopeInternal16(UChar* buffer) const
 127 {
 128     if (isSubstring()) {
 129         StringImpl::copyChars(
 130             buffer, substringBase()->m_value.characters16() + substringOffset(), m_length);
 131         return;
 132     }
 133
 134     resolveRopeInternal16NoSubstring(buffer);
 135 }
 136
 137 void JSRopeString::resolveRopeInternal16NoSubstring(UChar* buffer) const
 138 {
 139     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i) {
 140         if (fiber(i)->isRope()) {
 141             resolveRopeSlowCase(buffer);
 142             return;
 143         }
 144     }
 145
 146     UChar* position = buffer;
 147     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i) {
 148         const StringImpl& fiberString = *fiber(i)->m_value.impl();
 149         unsigned length = fiberString.length();
 150         if (fiberString.is8Bit())
 151             StringImpl::copyChars(position, fiberString.characters8(), length);
 152         else
 153             StringImpl::copyChars(position, fiberString.characters16(), length);
 154         position += length;
 155     }
 156     ASSERT((buffer + m_length) == position);
 157 }
 158
 159 void JSRopeString::resolveRopeToAtomicString(ExecState* exec) const
 160 {
 161     if (m_length > maxLengthForOnStackResolve) {
 162         resolveRope(exec);
 163         m_value = AtomicString(m_value);
 164         setIs8Bit(m_value.impl()->is8Bit());
 165         return;
 166     }
 167
 168     if (is8Bit()) {
 169         LChar buffer[maxLengthForOnStackResolve];
 170         resolveRopeInternal8(buffer);
 171         m_value = AtomicString(buffer, m_length);
 172         setIs8Bit(m_value.impl()->is8Bit());
 173     } else {
 174         UChar buffer[maxLengthForOnStackResolve];
 175         resolveRopeInternal16(buffer);
 176         m_value = AtomicString(buffer, m_length);
 177         setIs8Bit(m_value.impl()->is8Bit());
 178     }
 179
 180     clearFibers();
 181
 182     // If we resolved a string that didn't previously exist, notify the heap that we've grown.
 183     if (m_value.impl()->hasOneRef())
 184         Heap::heap(this)->reportExtraMemoryAllocated(m_value.impl()->cost());
 185 }
 186
 187 void JSRopeString::clearFibers() const
 188 {
 189     for (size_t i = 0; i < s_maxInternalRopeLength; ++i)
 190         u[i].number = 0;
 191 }
 192
 193 RefPtr<AtomicStringImpl> JSRopeString::resolveRopeToExistingAtomicString(ExecState* exec) const
 194 {
 195     if (m_length > maxLengthForOnStackResolve) {
 196         resolveRope(exec);
 197         if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(m_value.impl())) {
 198             m_value = *existingAtomicString;
 199             setIs8Bit(m_value.impl()->is8Bit());
 200             clearFibers();
 201             return existingAtomicString;
 202         }
 203         return nullptr;
 204     }
 205
 206     if (is8Bit()) {
 207         LChar buffer[maxLengthForOnStackResolve];
 208         resolveRopeInternal8(buffer);
 209         if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(buffer, m_length)) {
 210             m_value = *existingAtomicString;
 211             setIs8Bit(m_value.impl()->is8Bit());
 212             clearFibers();
 213             return existingAtomicString;
 214         }
 215     } else {
 216         UChar buffer[maxLengthForOnStackResolve];
 217         resolveRopeInternal16(buffer);
 218         if (RefPtr<AtomicStringImpl> existingAtomicString = AtomicStringImpl::lookUp(buffer, m_length)) {
 219             m_value = *existingAtomicString;
 220             setIs8Bit(m_value.impl()->is8Bit());
 221             clearFibers();
 222             return existingAtomicString;
 223         }
 224     }
 225
 226     return nullptr;
 227 }
 228
 229 void JSRopeString::resolveRope(ExecState* exec) const
 230 {
 231     ASSERT(isRope());
 232
 233     if (isSubstring()) {
 234         ASSERT(!substringBase()->isRope());
 235         m_value = substringBase()->m_value.substring(substringOffset(), m_length);
 236         substringBase().clear();
 237         return;
 238     }
 239
 240     if (is8Bit()) {
 241         LChar* buffer;
 242         if (RefPtr<StringImpl> newImpl = StringImpl::tryCreateUninitialized(m_length, buffer)) {
 243             Heap::heap(this)->reportExtraMemoryAllocated(newImpl->cost());
 244             m_value = newImpl.release();
 245         } else {
 246             outOfMemory(exec);
 247             return;
 248         }
 249         resolveRopeInternal8NoSubstring(buffer);
 250         clearFibers();
 251         ASSERT(!isRope());
 252         return;
 253     }
 254
 255     UChar* buffer;
 256     if (RefPtr<StringImpl> newImpl = StringImpl::tryCreateUninitialized(m_length, buffer)) {
 257         Heap::heap(this)->reportExtraMemoryAllocated(newImpl->cost());
 258         m_value = newImpl.release();
 259     } else {
 260         outOfMemory(exec);
 261         return;
 262     }
 263
 264     resolveRopeInternal16NoSubstring(buffer);
 265     clearFibers();
 266     ASSERT(!isRope());
 267 }
 268
 269 // Overview: These functions convert a JSString from holding a string in rope form
 270 // down to a simple String representation. It does so by building up the string
 271 // backwards, since we want to avoid recursion, we expect that the tree structure
 272 // representing the rope is likely imbalanced with more nodes down the left side
 273 // (since appending to the string is likely more common) - and as such resolving
 274 // in this fashion should minimize work queue size.  (If we built the queue forwards
 275 // we would likely have to place all of the constituent StringImpls into the
 276 // Vector before performing any concatenation, but by working backwards we likely
 277 // only fill the queue with the number of substrings at any given level in a
 278 // rope-of-ropes.)
 279 void JSRopeString::resolveRopeSlowCase8(LChar* buffer) const
 280 {
 281     LChar* position = buffer + m_length; // We will be working backwards over the rope.
 282     Vector<JSString*, 32, UnsafeVectorOverflow> workQueue; // Putting strings into a Vector is only OK because there are no GC points in this method.
 283
 284     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i)
 285         workQueue.append(fiber(i).get());
 286
 287     while (!workQueue.isEmpty()) {
 288         JSString* currentFiber = workQueue.last();
 289         workQueue.removeLast();
 290
 291         const LChar* characters;
 292
 293         if (currentFiber->isRope()) {
 294             JSRopeString* currentFiberAsRope = static_cast<JSRopeString*>(currentFiber);
 295             if (!currentFiberAsRope->isSubstring()) {
 296                 for (size_t i = 0; i < s_maxInternalRopeLength && currentFiberAsRope->fiber(i); ++i)
 297                     workQueue.append(currentFiberAsRope->fiber(i).get());
 298                 continue;
 299             }
 300             ASSERT(!currentFiberAsRope->substringBase()->isRope());
 301             characters =
 302                 currentFiberAsRope->substringBase()->m_value.characters8() +
 303                 currentFiberAsRope->substringOffset();
 304         } else
 305             characters = currentFiber->m_value.characters8();
 306
 307         unsigned length = currentFiber->length();
 308         position -= length;
 309         StringImpl::copyChars(position, characters, length);
 310     }
 311
 312     ASSERT(buffer == position);
 313 }
 314
 315 void JSRopeString::resolveRopeSlowCase(UChar* buffer) const
 316 {
 317     UChar* position = buffer + m_length; // We will be working backwards over the rope.
 318     Vector<JSString*, 32, UnsafeVectorOverflow> workQueue; // These strings are kept alive by the parent rope, so using a Vector is OK.
 319
 320     for (size_t i = 0; i < s_maxInternalRopeLength && fiber(i); ++i)
 321         workQueue.append(fiber(i).get());
 322
 323     while (!workQueue.isEmpty()) {
 324         JSString* currentFiber = workQueue.last();
 325         workQueue.removeLast();
 326
 327         if (currentFiber->isRope()) {
 328             JSRopeString* currentFiberAsRope = static_cast<JSRopeString*>(currentFiber);
 329             if (currentFiberAsRope->isSubstring()) {
 330                 ASSERT(!currentFiberAsRope->substringBase()->isRope());
 331                 StringImpl* string = static_cast<StringImpl*>(
 332                     currentFiberAsRope->substringBase()->m_value.impl());
 333                 unsigned offset = currentFiberAsRope->substringOffset();
 334                 unsigned length = currentFiberAsRope->length();
 335                 position -= length;
 336                 if (string->is8Bit())
 337                     StringImpl::copyChars(position, string->characters8() + offset, length);
 338                 else
 339                     StringImpl::copyChars(position, string->characters16() + offset, length);
 340                 continue;
 341             }
 342             for (size_t i = 0; i < s_maxInternalRopeLength && currentFiberAsRope->fiber(i); ++i)
 343                 workQueue.append(currentFiberAsRope->fiber(i).get());
 344             continue;
 345         }
 346
 347         StringImpl* string = static_cast<StringImpl*>(currentFiber->m_value.impl());
 348         unsigned length = string->length();
 349         position -= length;
 350         if (string->is8Bit())
 351             StringImpl::copyChars(position, string->characters8(), length);
 352         else
 353             StringImpl::copyChars(position, string->characters16(), length);
 354     }
 355
 356     ASSERT(buffer == position);
 357 }
 358
 359 void JSRopeString::outOfMemory(ExecState* exec) const
 360 {
 361     clearFibers();
 362     ASSERT(isRope());
 363     ASSERT(m_value.isNull());
 364     if (exec)
 365         throwOutOfMemoryError(exec);
 366 }
 367
 368 JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const
 369 {
 370     return const_cast<JSString*>(this);
 371 }
 372
 373 bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result) const
 374 {
 375     result = this;
 376     number = jsToNumber(view(exec));
 377     return false;
 378 }
 379
 380 double JSString::toNumber(ExecState* exec) const
 381 {
 382     return jsToNumber(view(exec));
 383 }
 384
 385 inline StringObject* StringObject::create(VM& vm, JSGlobalObject* globalObject, JSString* string)
 386 {
 387     StringObject* object = new (NotNull, allocateCell<StringObject>(vm.heap)) StringObject(vm, globalObject->stringObjectStructure());
 388     object->finishCreation(vm, string);
 389     return object;
 390 }
 391
 392 JSObject* JSString::toObject(ExecState* exec, JSGlobalObject* globalObject) const
 393 {
 394     return StringObject::create(exec->vm(), globalObject, const_cast<JSString*>(this));
 395 }
 396
 397 JSValue JSString::toThis(JSCell* cell, ExecState* exec, ECMAMode ecmaMode)
 398 {
 399     if (ecmaMode == StrictMode)
 400         return cell;
 401     return StringObject::create(exec->vm(), exec->lexicalGlobalObject(), jsCast<JSString*>(cell));
 402 }
 403
 404 bool JSString::getStringPropertyDescriptor(ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor)
 405 {
 406     if (propertyName == exec->propertyNames().length) {
 407         descriptor.setDescriptor(jsNumber(m_length), DontEnum | DontDelete | ReadOnly);
 408         return true;
 409     }
 410
 411     Optional<uint32_t> index = parseIndex(propertyName);
 412     if (index && index.value() < m_length) {
 413         descriptor.setDescriptor(getIndex(exec, index.value()), DontDelete | ReadOnly);
 414         return true;
 415     }
 416
 417     return false;
 418 }
 419
 420 JSString* jsStringWithCacheSlowCase(VM& vm, StringImpl& stringImpl)
 421 {
 422     if (JSString* string = vm.stringCache.get(&stringImpl))
 423         return string;
 424
 425     JSString* string = jsString(&vm, String(stringImpl));
 426     vm.lastCachedString.set(vm, string);
 427     return string;
 428 }
 429
 430 } // namespace JSC