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 "JSObject.h"

    28 #include "Operations.h"

    29 #include "StringObject.h"

    30 #include "StringPrototype.h"

    31 

    32 namespace JSC {

    33 

    34 // Overview: this methods converts a JSString from holding a string in rope form

    35 // down to a simple UString representation.  It does so by building up the string

    36 // backwards, since we want to avoid recursion, we expect that the tree structure

    37 // representing the rope is likely imbalanced with more nodes down the left side

    38 // (since appending to the string is likely more common) - and as such resolving

    39 // in this fashion should minimize work queue size.  (If we built the queue forwards

    40 // we would likely have to place all of the constituent UStringImpls into the

    41 // Vector before performing any concatenation, but by working backwards we likely

    42 // only fill the queue with the number of substrings at any given level in a

    43 // rope-of-ropes.)

    44 void JSString::resolveRope(ExecState* exec) const

    45 {

    46     ASSERT(isRope());

    47 

    48     // Allocate the buffer to hold the final string, position initially points to the end.

    49     UChar* buffer;

    50     if (PassRefPtr<UStringImpl> newImpl = UStringImpl::tryCreateUninitialized(m_length, buffer))

    51         m_value = newImpl;

    52     else {

    53         for (unsigned i = 0; i < m_fiberCount; ++i) {

    54             RopeImpl::deref(m_other.m_fibers[i]);

    55             m_other.m_fibers[i] = 0;

    56         }

    57         m_fiberCount = 0;

    58         ASSERT(!isRope());

    59         ASSERT(m_value == UString());

    60         if (exec)

    61             throwOutOfMemoryError(exec);

    62         return;

    63     }

    64     UChar* position = buffer + m_length;

    65 

    66     // Start with the current RopeImpl.

    67     Vector<RopeImpl::Fiber, 32> workQueue;

    68     RopeImpl::Fiber currentFiber;

    69     for (unsigned i = 0; i < (m_fiberCount - 1); ++i)

    70         workQueue.append(m_other.m_fibers[i]);

    71     currentFiber = m_other.m_fibers[m_fiberCount - 1];

    72     while (true) {

    73         if (RopeImpl::isRope(currentFiber)) {

    74             RopeImpl* rope = static_cast<RopeImpl*>(currentFiber);

    75             // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber'

    76             // (we will be working backwards over the rope).

    77             unsigned fiberCountMinusOne = rope->fiberCount() - 1;

    78             for (unsigned i = 0; i < fiberCountMinusOne; ++i)

    79                 workQueue.append(rope->fibers()[i]);

    80             currentFiber = rope->fibers()[fiberCountMinusOne];

    81         } else {

    82             UStringImpl* string = static_cast<UStringImpl*>(currentFiber);

    83             unsigned length = string->length();

    84             position -= length;

    85             UStringImpl::copyChars(position, string->characters(), length);

    86 

    87             // Was this the last item in the work queue?

    88             if (workQueue.isEmpty()) {

    89                 // Create a string from the UChar buffer, clear the rope RefPtr.

    90                 ASSERT(buffer == position);

    91                 for (unsigned i = 0; i < m_fiberCount; ++i) {

    92                     RopeImpl::deref(m_other.m_fibers[i]);

    93                     m_other.m_fibers[i] = 0;

    94                 }

    95                 m_fiberCount = 0;

    96 

    97                 ASSERT(!isRope());

    98                 return;

    99             }

   100 

   101             // No! - set the next item up to process.

   102             currentFiber = workQueue.last();

   103             workQueue.removeLast();

   104         }

   105     }

   106 }

   107 

   108 JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement)

   109 {

   110     if (!isRope()) {

   111         unsigned matchPosition = m_value.find(character);

   112         if (matchPosition == UString::NotFound)

   113             return JSValue(this);

   114         return jsString(exec, m_value.substr(0, matchPosition), replacement, m_value.substr(matchPosition + 1));

   115     }

   116 

   117     RopeIterator end;

   118     

   119     // Count total fibers and find matching string.

   120     size_t fiberCount = 0;

   121     UStringImpl* matchString = 0;

   122     int matchPosition = -1;

   123     for (RopeIterator it(m_other.m_fibers.data(), m_fiberCount); it != end; ++it) {

   124         ++fiberCount;

   125         if (matchString)

   126             continue;

   127 

   128         UStringImpl* string = *it;

   129         matchPosition = string->find(character);

   130         if (matchPosition == -1)

   131             continue;

   132         matchString = string;

   133     }

   134 

   135     if (!matchString)

   136         return this;

   137 

   138     RopeBuilder builder(replacement.size() ? fiberCount + 2 : fiberCount + 1);

   139     if (UNLIKELY(builder.isOutOfMemory()))

   140         return throwOutOfMemoryError(exec);

   141 

   142     for (RopeIterator it(m_other.m_fibers.data(), m_fiberCount); it != end; ++it) {

   143         UStringImpl* string = *it;

   144         if (string != matchString) {

   145             builder.append(UString(string));

   146             continue;

   147         }

   148 

   149         builder.append(UString(string).substr(0, matchPosition));

   150         if (replacement.size())

   151             builder.append(replacement);

   152         builder.append(UString(string).substr(matchPosition + 1));

   153         matchString = 0;

   154     }

   155 

   156     JSGlobalData* globalData = &exec->globalData();

   157     return JSValue(new (globalData) JSString(globalData, builder.release()));

   158 }

   159 

   160 JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i)

   161 {

   162     ASSERT(isRope());

   163     resolveRope(exec);

   164     // Return a safe no-value result, this should never be used, since the excetion will be thrown.

   165     if (exec->exception())

   166         return jsString(exec, "");

   167     ASSERT(!isRope());

   168     ASSERT(i < m_value.size());

   169     return jsSingleCharacterSubstring(exec, m_value, i);

   170 }

   171 

   172 JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const

   173 {

   174     return const_cast<JSString*>(this);

   175 }

   176 

   177 bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)

   178 {

   179     result = this;

   180     number = value(exec).toDouble();

   181     return false;

   182 }

   183 

   184 bool JSString::toBoolean(ExecState*) const

   185 {

   186     return m_length;

   187 }

   188 

   189 double JSString::toNumber(ExecState* exec) const

   190 {

   191     return value(exec).toDouble();

   192 }

   193 

   194 UString JSString::toString(ExecState* exec) const

   195 {

   196     return value(exec);

   197 }

   198 

   199 inline StringObject* StringObject::create(ExecState* exec, JSString* string)

   200 {

   201     return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);

   202 }

   203 

   204 JSObject* JSString::toObject(ExecState* exec) const

   205 {

   206     return StringObject::create(exec, const_cast<JSString*>(this));

   207 }

   208 

   209 JSObject* JSString::toThisObject(ExecState* exec) const

   210 {

   211     return StringObject::create(exec, const_cast<JSString*>(this));

   212 }

   213 

   214 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)

   215 {

   216     // The semantics here are really getPropertySlot, not getOwnPropertySlot.

   217     // This function should only be called by JSValue::get.

   218     if (getStringPropertySlot(exec, propertyName, slot))

   219         return true;

   220     if (propertyName == exec->propertyNames().underscoreProto) {

   221         slot.setValue(exec->lexicalGlobalObject()->stringPrototype());

   222         return true;

   223     }

   224     slot.setBase(this);

   225     JSObject* object;

   226     for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {

   227         object = asObject(prototype);

   228         if (object->getOwnPropertySlot(exec, propertyName, slot))

   229             return true;

   230     }

   231     slot.setUndefined();

   232     return true;

   233 }

   234 

   235 bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

   236 {

   237     if (propertyName == exec->propertyNames().length) {

   238         descriptor.setDescriptor(jsNumber(exec, m_length), DontEnum | DontDelete | ReadOnly);

   239         return true;

   240     }

   241     

   242     bool isStrictUInt32;

   243     unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);

   244     if (isStrictUInt32 && i < m_length) {

   245         descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly);

   246         return true;

   247     }

   248     

   249     return false;

   250 }

   251 

   252 bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

   253 {

   254     if (getStringPropertyDescriptor(exec, propertyName, descriptor))

   255         return true;

   256     if (propertyName != exec->propertyNames().underscoreProto)

   257         return false;

   258     descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum);

   259     return true;

   260 }

   261 

   262 bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)

   263 {

   264     // The semantics here are really getPropertySlot, not getOwnPropertySlot.

   265     // This function should only be called by JSValue::get.

   266     if (getStringPropertySlot(exec, propertyName, slot))

   267         return true;

   268     return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);

   269 }

   270 

   271 } // namespace JSC