JavaScriptCore/runtime/JSString.cpp - WebKit - Git at Google

 /*
  *  Copyright (C) 1999-2002 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
  *  Copyright (C) 2004, 2007, 2008 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */

 #include "config.h"
 #include "JSString.h"

 #include "JSGlobalObject.h"
 #include "JSObject.h"
 #include "Operations.h"
 #include "StringObject.h"
 #include "StringPrototype.h"

 namespace JSC {

 void JSString::Rope::destructNonRecursive()
 {
     Vector<Rope*, 32> workQueue;
     Rope* rope = this;

     while (true) {
         unsigned length = rope->ropeLength();
         for (unsigned i = 0; i < length; ++i) {
             Fiber& fiber = rope->fibers(i);
             if (fiber.isString())
                 fiber.string()->deref();
             else {
                 Rope* nextRope = fiber.rope();
                 if (nextRope->hasOneRef())
                     workQueue.append(nextRope);
                 else
                     nextRope->deref();
             }
         }
         if (rope != this)
             fastFree(rope);

         if (workQueue.isEmpty())
             return;

         rope = workQueue.last();
         workQueue.removeLast();
     }
 }

 JSString::Rope::~Rope()
 {
     destructNonRecursive();
 }

 // Overview: this methods converts a JSString from holding a string in rope form
 // down to a simple UString representation.  It does so by building up the string
 // backwards, since we want to avoid recursion, we expect that the tree structure
 // representing the rope is likely imbalanced with more nodes down the left side
 // (since appending to the string is likely more common) - and as such resolving
 // in this fashion should minimize work queue size.  (If we built the queue forwards
 // we would likely have to place all of the constituent UString::Reps into the
 // Vector before performing any concatenation, but by working backwards we likely
 // only fill the queue with the number of substrings at any given level in a
 // rope-of-ropes.)
 void JSString::resolveRope(ExecState* exec) const
 {
     ASSERT(isRope());

     // Allocate the buffer to hold the final string, position initially points to the end.
     UChar* buffer;
     if (PassRefPtr<UStringImpl> newImpl = UStringImpl::tryCreateUninitialized(m_stringLength, buffer))
         m_value = newImpl;
     else {
         for (unsigned i = 0; i < m_ropeLength; ++i) {
             m_fibers[i].deref();
             m_fibers[i] = static_cast<void*>(0);
         }
         m_ropeLength = 0;
         ASSERT(!isRope());
         ASSERT(m_value == UString());
         throwOutOfMemoryError(exec);
         return;
     }
     UChar* position = buffer + m_stringLength;

     // Start with the current Rope.
     Vector<Rope::Fiber, 32> workQueue;
     Rope::Fiber currentFiber;
     for (unsigned i = 0; i < (m_ropeLength - 1); ++i)
         workQueue.append(m_fibers[i]);
     currentFiber = m_fibers[m_ropeLength - 1];
     while (true) {
         if (currentFiber.isRope()) {
             Rope* rope = currentFiber.rope();
             // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber'
             // (we will be working backwards over the rope).
             unsigned ropeLengthMinusOne = rope->ropeLength() - 1;
             for (unsigned i = 0; i < ropeLengthMinusOne; ++i)
                 workQueue.append(rope->fibers(i));
             currentFiber = rope->fibers(ropeLengthMinusOne);
         } else {
             UString::Rep* string = currentFiber.string();
             unsigned length = string->size();
             position -= length;
             UStringImpl::copyChars(position, string->data(), length);

             // Was this the last item in the work queue?
             if (workQueue.isEmpty()) {
                 // Create a string from the UChar buffer, clear the rope RefPtr.
                 ASSERT(buffer == position);
                 for (unsigned i = 0; i < m_ropeLength; ++i) {
                     m_fibers[i].deref();
                     m_fibers[i] = static_cast<void*>(0);
                 }
                 m_ropeLength = 0;

                 ASSERT(!isRope());
                 return;
             }

             // No! - set the next item up to process.
             currentFiber = workQueue.last();
             workQueue.removeLast();
         }
     }
 }

 JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const
 {
     return const_cast<JSString*>(this);
 }

 bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)
 {
     result = this;
     number = value(exec).toDouble();
     return false;
 }

 bool JSString::toBoolean(ExecState*) const
 {
     return m_stringLength;
 }

 double JSString::toNumber(ExecState* exec) const
 {
     return value(exec).toDouble();
 }

 UString JSString::toString(ExecState* exec) const
 {
     return value(exec);
 }

 UString JSString::toThisString(ExecState* exec) const
 {
     return value(exec);
 }

 JSString* JSString::toThisJSString(ExecState*)
 {
     return this;
 }

 inline StringObject* StringObject::create(ExecState* exec, JSString* string)
 {
     return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);
 }

 JSObject* JSString::toObject(ExecState* exec) const
 {
     return StringObject::create(exec, const_cast<JSString*>(this));
 }

 JSObject* JSString::toThisObject(ExecState* exec) const
 {
     return StringObject::create(exec, const_cast<JSString*>(this));
 }

 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
 {
     // The semantics here are really getPropertySlot, not getOwnPropertySlot.
     // This function should only be called by JSValue::get.
     if (getStringPropertySlot(exec, propertyName, slot))
         return true;
     if (propertyName == exec->propertyNames().underscoreProto) {
         slot.setValue(exec->lexicalGlobalObject()->stringPrototype());
         return true;
     }
     slot.setBase(this);
     JSObject* object;
     for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {
         object = asObject(prototype);
         if (object->getOwnPropertySlot(exec, propertyName, slot))
             return true;
     }
     slot.setUndefined();
     return true;
 }

 bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
 {
     if (propertyName == exec->propertyNames().length) {
         descriptor.setDescriptor(jsNumber(exec, m_stringLength), DontEnum | DontDelete | ReadOnly);
         return true;
     }

     bool isStrictUInt32;
     unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);
     if (isStrictUInt32 && i < m_stringLength) {
         descriptor.setDescriptor(jsSingleCharacterSubstring(exec, value(exec), i), DontDelete | ReadOnly);
         return true;
     }

     return false;
 }

 bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
 {
     if (getStringPropertyDescriptor(exec, propertyName, descriptor))
         return true;
     if (propertyName != exec->propertyNames().underscoreProto)
         return false;
     descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum);
     return true;
 }

 bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
 {
     // The semantics here are really getPropertySlot, not getOwnPropertySlot.
     // This function should only be called by JSValue::get.
     if (getStringPropertySlot(exec, propertyName, slot))
         return true;
     return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);
 }

 } // namespace JSC
	/*
	* Copyright (C) 1999-2002 Harri Porten (porten@kde.org)
	* Copyright (C) 2001 Peter Kelly (pmk@post.com)
	* Copyright (C) 2004, 2007, 2008 Apple Inc. All rights reserved.
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Library General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public License
	* along with this library; see the file COPYING.LIB. If not, write to
	* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*
	*/

	#include "config.h"
	#include "JSString.h"

	#include "JSGlobalObject.h"
	#include "JSObject.h"
	#include "Operations.h"
	#include "StringObject.h"
	#include "StringPrototype.h"

	namespace JSC {

	void JSString::Rope::destructNonRecursive()
	{
	Vector<Rope*, 32> workQueue;
	Rope* rope = this;

	while (true) {
	unsigned length = rope->ropeLength();
	for (unsigned i = 0; i < length; ++i) {
	Fiber& fiber = rope->fibers(i);
	if (fiber.isString())
	fiber.string()->deref();
	else {
	Rope* nextRope = fiber.rope();
	if (nextRope->hasOneRef())
	workQueue.append(nextRope);
	else
	nextRope->deref();
	}
	}
	if (rope != this)
	fastFree(rope);

	if (workQueue.isEmpty())
	return;

	rope = workQueue.last();
	workQueue.removeLast();
	}
	}

	JSString::Rope::~Rope()
	{
	destructNonRecursive();
	}

	// Overview: this methods converts a JSString from holding a string in rope form
	// down to a simple UString representation. It does so by building up the string
	// backwards, since we want to avoid recursion, we expect that the tree structure
	// representing the rope is likely imbalanced with more nodes down the left side
	// (since appending to the string is likely more common) - and as such resolving
	// in this fashion should minimize work queue size. (If we built the queue forwards
	// we would likely have to place all of the constituent UString::Reps into the
	// Vector before performing any concatenation, but by working backwards we likely
	// only fill the queue with the number of substrings at any given level in a
	// rope-of-ropes.)
	void JSString::resolveRope(ExecState* exec) const
	{
	ASSERT(isRope());

	// Allocate the buffer to hold the final string, position initially points to the end.
	UChar* buffer;
	if (PassRefPtr<UStringImpl> newImpl = UStringImpl::tryCreateUninitialized(m_stringLength, buffer))
	m_value = newImpl;
	else {
	for (unsigned i = 0; i < m_ropeLength; ++i) {
	m_fibers[i].deref();
	m_fibers[i] = static_cast<void*>(0);
	}
	m_ropeLength = 0;
	ASSERT(!isRope());
	ASSERT(m_value == UString());
	throwOutOfMemoryError(exec);
	return;
	}
	UChar* position = buffer + m_stringLength;

	// Start with the current Rope.
	Vector<Rope::Fiber, 32> workQueue;
	Rope::Fiber currentFiber;
	for (unsigned i = 0; i < (m_ropeLength - 1); ++i)
	workQueue.append(m_fibers[i]);
	currentFiber = m_fibers[m_ropeLength - 1];
	while (true) {
	if (currentFiber.isRope()) {
	Rope* rope = currentFiber.rope();
	// Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber'
	// (we will be working backwards over the rope).
	unsigned ropeLengthMinusOne = rope->ropeLength() - 1;
	for (unsigned i = 0; i < ropeLengthMinusOne; ++i)
	workQueue.append(rope->fibers(i));
	currentFiber = rope->fibers(ropeLengthMinusOne);
	} else {
	UString::Rep* string = currentFiber.string();
	unsigned length = string->size();
	position -= length;
	UStringImpl::copyChars(position, string->data(), length);

	// Was this the last item in the work queue?
	if (workQueue.isEmpty()) {
	// Create a string from the UChar buffer, clear the rope RefPtr.
	ASSERT(buffer == position);
	for (unsigned i = 0; i < m_ropeLength; ++i) {
	m_fibers[i].deref();
	m_fibers[i] = static_cast<void*>(0);
	}
	m_ropeLength = 0;

	ASSERT(!isRope());
	return;
	}

	// No! - set the next item up to process.
	currentFiber = workQueue.last();
	workQueue.removeLast();
	}
	}
	}

	JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const
	{
	return const_cast<JSString*>(this);
	}

	bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)
	{
	result = this;
	number = value(exec).toDouble();
	return false;
	}

	bool JSString::toBoolean(ExecState*) const
	{
	return m_stringLength;
	}

	double JSString::toNumber(ExecState* exec) const
	{
	return value(exec).toDouble();
	}

	UString JSString::toString(ExecState* exec) const
	{
	return value(exec);
	}

	UString JSString::toThisString(ExecState* exec) const
	{
	return value(exec);
	}

	JSString* JSString::toThisJSString(ExecState*)
	{
	return this;
	}

	inline StringObject* StringObject::create(ExecState* exec, JSString* string)
	{
	return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);
	}

	JSObject* JSString::toObject(ExecState* exec) const
	{
	return StringObject::create(exec, const_cast<JSString*>(this));
	}

	JSObject* JSString::toThisObject(ExecState* exec) const
	{
	return StringObject::create(exec, const_cast<JSString*>(this));
	}

	bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
	{
	// The semantics here are really getPropertySlot, not getOwnPropertySlot.
	// This function should only be called by JSValue::get.
	if (getStringPropertySlot(exec, propertyName, slot))
	return true;
	if (propertyName == exec->propertyNames().underscoreProto) {
	slot.setValue(exec->lexicalGlobalObject()->stringPrototype());
	return true;
	}
	slot.setBase(this);
	JSObject* object;
	for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {
	object = asObject(prototype);
	if (object->getOwnPropertySlot(exec, propertyName, slot))
	return true;
	}
	slot.setUndefined();
	return true;
	}

	bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
	{
	if (propertyName == exec->propertyNames().length) {
	descriptor.setDescriptor(jsNumber(exec, m_stringLength), DontEnum \| DontDelete \| ReadOnly);
	return true;
	}

	bool isStrictUInt32;
	unsigned i = propertyName.toStrictUInt32(&isStrictUInt32);
	if (isStrictUInt32 && i < m_stringLength) {
	descriptor.setDescriptor(jsSingleCharacterSubstring(exec, value(exec), i), DontDelete \| ReadOnly);
	return true;
	}

	return false;
	}

	bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
	{
	if (getStringPropertyDescriptor(exec, propertyName, descriptor))
	return true;
	if (propertyName != exec->propertyNames().underscoreProto)
	return false;
	descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum);
	return true;
	}

	bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
	{
	// The semantics here are really getPropertySlot, not getOwnPropertySlot.
	// This function should only be called by JSValue::get.
	if (getStringPropertySlot(exec, propertyName, slot))
	return true;
	return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);
	}

	} // namespace JSC