Source/JavaScriptCore/runtime/JSString.h - WebKit - Git at Google

 /*
  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
  *  Copyright (C) 2003, 2004, 2005, 2006, 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.
  *
  */

 #ifndef JSString_h
 #define JSString_h
 #include "CallFrame.h"
 #include "CommonIdentifiers.h"
 #include "Identifier.h"
 #include "PropertyDescriptor.h"
 #include "PropertySlot.h"
 #include "Structure.h"

 namespace JSC {

     class JSString;
     class JSRopeString;
     class LLIntOffsetsExtractor;

     JSString* jsEmptyString(JSGlobalData*);
     JSString* jsEmptyString(ExecState*);
     JSString* jsString(JSGlobalData*, const UString&); // returns empty string if passed null string
     JSString* jsString(ExecState*, const UString&); // returns empty string if passed null string

     JSString* jsSingleCharacterString(JSGlobalData*, UChar);
     JSString* jsSingleCharacterString(ExecState*, UChar);
     JSString* jsSingleCharacterSubstring(ExecState*, const UString&, unsigned offset);
     JSString* jsSubstring(JSGlobalData*, const UString&, unsigned offset, unsigned length);
     JSString* jsSubstring(ExecState*, const UString&, unsigned offset, unsigned length);

     // Non-trivial strings are two or more characters long.
     // These functions are faster than just calling jsString.
     JSString* jsNontrivialString(JSGlobalData*, const UString&);
     JSString* jsNontrivialString(ExecState*, const UString&);
     JSString* jsNontrivialString(JSGlobalData*, const char*);
     JSString* jsNontrivialString(ExecState*, const char*);

     // Should be used for strings that are owned by an object that will
     // likely outlive the JSValue this makes, such as the parse tree or a
     // DOM object that contains a UString
     JSString* jsOwnedString(JSGlobalData*, const UString&);
     JSString* jsOwnedString(ExecState*, const UString&);

     JSRopeString* jsStringBuilder(JSGlobalData*);

     class JSString : public JSCell {
     public:
         friend class JIT;
         friend class JSGlobalData;
         friend class SpecializedThunkJIT;
         friend class JSRopeString;
         friend struct ThunkHelpers;

         typedef JSCell Base;

         static void destroy(JSCell*);

     private:
         JSString(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
             : JSCell(globalData, globalData.stringStructure.get())
             , m_value(value)
         {
         }

         JSString(JSGlobalData& globalData)
             : JSCell(globalData, globalData.stringStructure.get())
         {
         }

         void finishCreation(JSGlobalData& globalData, size_t length)
         {
             ASSERT(!m_value.isNull());
             Base::finishCreation(globalData);
             m_length = length;
             m_is8Bit = m_value.impl()->is8Bit();
         }

         void finishCreation(JSGlobalData& globalData, size_t length, size_t cost)
         {
             ASSERT(!m_value.isNull());
             Base::finishCreation(globalData);
             m_length = length;
             m_is8Bit = m_value.impl()->is8Bit();
             Heap::heap(this)->reportExtraMemoryCost(cost);
         }

     protected:
         void finishCreation(JSGlobalData& globalData)
         {
             Base::finishCreation(globalData);
             m_length = 0;
             m_is8Bit = true;
         }

     public:
         static JSString* create(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
         {
             ASSERT(value);
             size_t length = value->length();
             size_t cost = value->cost();
             JSString* newString = new (NotNull, allocateCell<JSString>(globalData.heap)) JSString(globalData, value);
             newString->finishCreation(globalData, length, cost);
             return newString;
         }
         static JSString* createHasOtherOwner(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
         {
             ASSERT(value);
             size_t length = value->length();
             JSString* newString = new (NotNull, allocateCell<JSString>(globalData.heap)) JSString(globalData, value);
             newString->finishCreation(globalData, length);
             return newString;
         }

         const UString& value(ExecState*) const;
         const UString& tryGetValue() const;
         unsigned length() { return m_length; }

         JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
         JS_EXPORT_PRIVATE bool toBoolean(ExecState*) const;
         bool getPrimitiveNumber(ExecState*, double& number, JSValue&) const;
         JSObject* toObject(ExecState*, JSGlobalObject*) const;
         double toNumber(ExecState*) const;

         bool getStringPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
         bool getStringPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
         bool getStringPropertyDescriptor(ExecState*, const Identifier& propertyName, PropertyDescriptor&);

         bool canGetIndex(unsigned i) { return i < m_length; }
         JSString* getIndex(ExecState*, unsigned);

         static Structure* createStructure(JSGlobalData& globalData, JSGlobalObject* globalObject, JSValue proto)
         {
             return Structure::create(globalData, globalObject, proto, TypeInfo(StringType, OverridesGetOwnPropertySlot), &s_info);
         }

         static size_t offsetOfLength() { return OBJECT_OFFSETOF(JSString, m_length); }
         static size_t offsetOfValue() { return OBJECT_OFFSETOF(JSString, m_value); }

         static JS_EXPORTDATA const ClassInfo s_info;

         static void visitChildren(JSCell*, SlotVisitor&);

     protected:
         bool isRope() const { return m_value.isNull(); }
         bool is8Bit() const { return m_is8Bit; }

         // A string is represented either by a UString or a rope of fibers.
         bool m_is8Bit : 1;
         unsigned m_length;
         mutable UString m_value;

     private:
         friend class LLIntOffsetsExtractor;

         static JSObject* toThisObject(JSCell*, ExecState*);

         // Actually getPropertySlot, not getOwnPropertySlot (see JSCell).
         static bool getOwnPropertySlot(JSCell*, ExecState*, const Identifier& propertyName, PropertySlot&);
         static bool getOwnPropertySlotByIndex(JSCell*, ExecState*, unsigned propertyName, PropertySlot&);

         UString& string() { ASSERT(!isRope()); return m_value; }

         friend JSValue jsString(ExecState*, JSString*, JSString*);
         friend JSString* jsSubstring(ExecState*, JSString*, unsigned offset, unsigned length);
     };

     class JSRopeString : public JSString {
         friend class JSString;

         friend JSRopeString* jsStringBuilder(JSGlobalData*);

         class RopeBuilder {
         public:
             RopeBuilder(JSGlobalData& globalData)
             : m_globalData(globalData)
             , m_jsString(jsStringBuilder(&globalData))
             , m_index(0)
             {
             }

             void append(JSString* jsString)
             {
                 if (m_index == JSRopeString::s_maxInternalRopeLength)
                     expand();
                 m_jsString->m_fibers[m_index++].set(m_globalData, m_jsString, jsString);
                 m_jsString->m_length += jsString->m_length;
                 m_jsString->m_is8Bit = m_jsString->m_is8Bit && jsString->m_is8Bit;
             }

             JSRopeString* release()
             {
                 JSRopeString* tmp = m_jsString;
                 m_jsString = 0;
                 return tmp;
             }

             unsigned length() { return m_jsString->m_length; }

         private:
             void expand();

             JSGlobalData& m_globalData;
             JSRopeString* m_jsString;
             size_t m_index;
         };

     private:
         JSRopeString(JSGlobalData& globalData)
             : JSString(globalData)
         {
         }

         void finishCreation(JSGlobalData& globalData, JSString* s1, JSString* s2)
         {
             Base::finishCreation(globalData);
             m_length = s1->length() + s2->length();
             m_is8Bit = (s1->is8Bit() && s2->is8Bit());
             m_fibers[0].set(globalData, this, s1);
             m_fibers[1].set(globalData, this, s2);
         }

         void finishCreation(JSGlobalData& globalData, JSString* s1, JSString* s2, JSString* s3)
         {
             Base::finishCreation(globalData);
             m_length = s1->length() + s2->length() + s3->length();
             m_is8Bit = (s1->is8Bit() && s2->is8Bit() &&  s3->is8Bit());
             m_fibers[0].set(globalData, this, s1);
             m_fibers[1].set(globalData, this, s2);
             m_fibers[2].set(globalData, this, s3);
         }

         void finishCreation(JSGlobalData& globalData)
         {
             JSString::finishCreation(globalData);
         }

         static JSRopeString* createNull(JSGlobalData& globalData)
         {
             JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
             newString->finishCreation(globalData);
             return newString;
         }

     public:
         static JSString* create(JSGlobalData& globalData, JSString* s1, JSString* s2)
         {
             JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
             newString->finishCreation(globalData, s1, s2);
             return newString;
         }
         static JSString* create(JSGlobalData& globalData, JSString* s1, JSString* s2, JSString* s3)
         {
             JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
             newString->finishCreation(globalData, s1, s2, s3);
             return newString;
         }

         void visitFibers(SlotVisitor&);

     private:
         friend JSValue jsString(ExecState*, Register*, unsigned);
         friend JSValue jsStringFromArguments(ExecState*, JSValue);

         JS_EXPORT_PRIVATE void resolveRope(ExecState*) const;
         void resolveRopeSlowCase8(LChar*) const;
         void resolveRopeSlowCase(UChar*) const;
         void outOfMemory(ExecState*) const;

         JSString* getIndexSlowCase(ExecState*, unsigned);

         static const unsigned s_maxInternalRopeLength = 3;

         mutable FixedArray<WriteBarrier<JSString>, s_maxInternalRopeLength> m_fibers;
     };

     JSString* asString(JSValue);

     inline JSString* asString(JSValue value)
     {
         ASSERT(value.asCell()->isString());
         return jsCast<JSString*>(value.asCell());
     }

     inline JSString* jsEmptyString(JSGlobalData* globalData)
     {
         return globalData->smallStrings.emptyString(globalData);
     }

     inline JSString* jsSingleCharacterString(JSGlobalData* globalData, UChar c)
     {
         if (c <= maxSingleCharacterString)
             return globalData->smallStrings.singleCharacterString(globalData, c);
         return JSString::create(*globalData, UString(&c, 1).impl());
     }

     inline JSString* jsSingleCharacterSubstring(ExecState* exec, const UString& s, unsigned offset)
     {
         JSGlobalData* globalData = &exec->globalData();
         ASSERT(offset < static_cast<unsigned>(s.length()));
         UChar c = s[offset];
         if (c <= maxSingleCharacterString)
             return globalData->smallStrings.singleCharacterString(globalData, c);
         return JSString::create(*globalData, StringImpl::create(s.impl(), offset, 1));
     }

     inline JSString* jsNontrivialString(JSGlobalData* globalData, const char* s)
     {
         ASSERT(s);
         ASSERT(s[0]);
         ASSERT(s[1]);
         return JSString::create(*globalData, UString(s).impl());
     }

     inline JSString* jsNontrivialString(JSGlobalData* globalData, const UString& s)
     {
         ASSERT(s.length() > 1);
         return JSString::create(*globalData, s.impl());
     }

     inline const UString& JSString::value(ExecState* exec) const
     {
         if (isRope())
             static_cast<const JSRopeString*>(this)->resolveRope(exec);
         return m_value;
     }

     inline const UString& JSString::tryGetValue() const
     {
         if (isRope())
             static_cast<const JSRopeString*>(this)->resolveRope(0);
         return m_value;
     }

     inline JSString* JSString::getIndex(ExecState* exec, unsigned i)
     {
         ASSERT(canGetIndex(i));
         if (isRope())
             return static_cast<JSRopeString*>(this)->getIndexSlowCase(exec, i);
         ASSERT(i < m_value.length());
         return jsSingleCharacterSubstring(exec, m_value, i);
     }

     inline JSString* jsString(JSGlobalData* globalData, const UString& s)
     {
         int size = s.length();
         if (!size)
             return globalData->smallStrings.emptyString(globalData);
         if (size == 1) {
             UChar c = s[0];
             if (c <= maxSingleCharacterString)
                 return globalData->smallStrings.singleCharacterString(globalData, c);
         }
         return JSString::create(*globalData, s.impl());
     }

     inline JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length)
     {
         ASSERT(offset <= static_cast<unsigned>(s->length()));
         ASSERT(length <= static_cast<unsigned>(s->length()));
         ASSERT(offset + length <= static_cast<unsigned>(s->length()));
         JSGlobalData* globalData = &exec->globalData();
         if (!length)
             return globalData->smallStrings.emptyString(globalData);
         return jsSubstring(globalData, s->value(exec), offset, length);
     }

     inline JSString* jsSubstring8(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
     {
         ASSERT(offset <= static_cast<unsigned>(s.length()));
         ASSERT(length <= static_cast<unsigned>(s.length()));
         ASSERT(offset + length <= static_cast<unsigned>(s.length()));
         if (!length)
             return globalData->smallStrings.emptyString(globalData);
         if (length == 1) {
             UChar c = s[offset];
             if (c <= maxSingleCharacterString)
                 return globalData->smallStrings.singleCharacterString(globalData, c);
         }
         return JSString::createHasOtherOwner(*globalData, StringImpl::create8(s.impl(), offset, length));
     }

     inline JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
     {
         ASSERT(offset <= static_cast<unsigned>(s.length()));
         ASSERT(length <= static_cast<unsigned>(s.length()));
         ASSERT(offset + length <= static_cast<unsigned>(s.length()));
         if (!length)
             return globalData->smallStrings.emptyString(globalData);
         if (length == 1) {
             UChar c = s[offset];
             if (c <= maxSingleCharacterString)
                 return globalData->smallStrings.singleCharacterString(globalData, c);
         }
         return JSString::createHasOtherOwner(*globalData, StringImpl::create(s.impl(), offset, length));
     }

     inline JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
     {
         int size = s.length();
         if (!size)
             return globalData->smallStrings.emptyString(globalData);
         if (size == 1) {
             UChar c = s[0];
             if (c <= maxSingleCharacterString)
                 return globalData->smallStrings.singleCharacterString(globalData, c);
         }
         return JSString::createHasOtherOwner(*globalData, s.impl());
     }

     inline JSRopeString* jsStringBuilder(JSGlobalData* globalData)
     {
         return JSRopeString::createNull(*globalData);
     }

     inline JSString* jsEmptyString(ExecState* exec) { return jsEmptyString(&exec->globalData()); }
     inline JSString* jsString(ExecState* exec, const UString& s) { return jsString(&exec->globalData(), s); }
     inline JSString* jsSingleCharacterString(ExecState* exec, UChar c) { return jsSingleCharacterString(&exec->globalData(), c); }
     inline JSString* jsSubstring8(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring8(&exec->globalData(), s, offset, length); }
     inline JSString* jsSubstring(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring(&exec->globalData(), s, offset, length); }
     inline JSString* jsNontrivialString(ExecState* exec, const UString& s) { return jsNontrivialString(&exec->globalData(), s); }
     inline JSString* jsNontrivialString(ExecState* exec, const char* s) { return jsNontrivialString(&exec->globalData(), s); }
     inline JSString* jsOwnedString(ExecState* exec, const UString& s) { return jsOwnedString(&exec->globalData(), s); }

     ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
     {
         if (propertyName == exec->propertyNames().length) {
             slot.setValue(jsNumber(m_length));
             return true;
         }

         bool isStrictUInt32;
         unsigned i = propertyName.toUInt32(isStrictUInt32);
         if (isStrictUInt32 && i < m_length) {
             slot.setValue(getIndex(exec, i));
             return true;
         }

         return false;
     }

     ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
     {
         if (propertyName < m_length) {
             slot.setValue(getIndex(exec, propertyName));
             return true;
         }

         return false;
     }

     inline bool isJSString(JSValue v) { return v.isCell() && v.asCell()->classInfo() == &JSString::s_info; }

     inline bool JSCell::toBoolean(ExecState* exec) const
     {
         if (isString())
             return static_cast<const JSString*>(this)->toBoolean(exec);
         return !structure()->typeInfo().masqueradesAsUndefined();
     }

     // --- JSValue inlines ----------------------------

     inline bool JSValue::toBoolean(ExecState* exec) const
     {
         if (isInt32())
             return asInt32();
         if (isDouble())
             return asDouble() > 0.0 || asDouble() < 0.0; // false for NaN
         if (isCell())
             return asCell()->toBoolean(exec);
         return isTrue(); // false, null, and undefined all convert to false.
     }

     inline JSString* JSValue::toString(ExecState* exec) const
     {
         if (isString())
             return jsCast<JSString*>(asCell());
         return toStringSlowCase(exec);
     }

     inline UString JSValue::toUString(ExecState* exec) const
     {
         if (isString())
             return static_cast<JSString*>(asCell())->value(exec);
         return toUStringSlowCase(exec);
     }

     ALWAYS_INLINE UString inlineJSValueNotStringtoUString(const JSValue& value, ExecState* exec)
     {
         JSGlobalData& globalData = exec->globalData();
         if (value.isInt32())
             return globalData.numericStrings.add(value.asInt32());
         if (value.isDouble())
             return globalData.numericStrings.add(value.asDouble());
         if (value.isTrue())
             return globalData.propertyNames->trueKeyword.ustring();
         if (value.isFalse())
             return globalData.propertyNames->falseKeyword.ustring();
         if (value.isNull())
             return globalData.propertyNames->nullKeyword.ustring();
         if (value.isUndefined())
             return globalData.propertyNames->undefinedKeyword.ustring();
         return value.toString(exec)->value(exec);
     }

     ALWAYS_INLINE UString JSValue::toUStringInline(ExecState* exec) const
     {
         if (isString())
             return static_cast<JSString*>(asCell())->value(exec);

         return inlineJSValueNotStringtoUString(*this, exec);
     }

 } // namespace JSC

 #endif // JSString_h
	/*
	* Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
	* Copyright (C) 2001 Peter Kelly (pmk@post.com)
	* Copyright (C) 2003, 2004, 2005, 2006, 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.
	*
	*/

	#ifndef JSString_h
	#define JSString_h
	#include "CallFrame.h"
	#include "CommonIdentifiers.h"
	#include "Identifier.h"
	#include "PropertyDescriptor.h"
	#include "PropertySlot.h"
	#include "Structure.h"

	namespace JSC {

	class JSString;
	class JSRopeString;
	class LLIntOffsetsExtractor;

	JSString* jsEmptyString(JSGlobalData*);
	JSString* jsEmptyString(ExecState*);
	JSString* jsString(JSGlobalData*, const UString&); // returns empty string if passed null string
	JSString* jsString(ExecState*, const UString&); // returns empty string if passed null string

	JSString* jsSingleCharacterString(JSGlobalData*, UChar);
	JSString* jsSingleCharacterString(ExecState*, UChar);
	JSString* jsSingleCharacterSubstring(ExecState*, const UString&, unsigned offset);
	JSString* jsSubstring(JSGlobalData*, const UString&, unsigned offset, unsigned length);
	JSString* jsSubstring(ExecState*, const UString&, unsigned offset, unsigned length);

	// Non-trivial strings are two or more characters long.
	// These functions are faster than just calling jsString.
	JSString* jsNontrivialString(JSGlobalData*, const UString&);
	JSString* jsNontrivialString(ExecState*, const UString&);
	JSString* jsNontrivialString(JSGlobalData, const char);
	JSString* jsNontrivialString(ExecState, const char);

	// Should be used for strings that are owned by an object that will
	// likely outlive the JSValue this makes, such as the parse tree or a
	// DOM object that contains a UString
	JSString* jsOwnedString(JSGlobalData*, const UString&);
	JSString* jsOwnedString(ExecState*, const UString&);

	JSRopeString* jsStringBuilder(JSGlobalData*);

	class JSString : public JSCell {
	public:
	friend class JIT;
	friend class JSGlobalData;
	friend class SpecializedThunkJIT;
	friend class JSRopeString;
	friend struct ThunkHelpers;

	typedef JSCell Base;

	static void destroy(JSCell*);

	private:
	JSString(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
	: JSCell(globalData, globalData.stringStructure.get())
	, m_value(value)
	{
	}

	JSString(JSGlobalData& globalData)
	: JSCell(globalData, globalData.stringStructure.get())
	{
	}

	void finishCreation(JSGlobalData& globalData, size_t length)
	{
	ASSERT(!m_value.isNull());
	Base::finishCreation(globalData);
	m_length = length;
	m_is8Bit = m_value.impl()->is8Bit();
	}

	void finishCreation(JSGlobalData& globalData, size_t length, size_t cost)
	{
	ASSERT(!m_value.isNull());
	Base::finishCreation(globalData);
	m_length = length;
	m_is8Bit = m_value.impl()->is8Bit();
	Heap::heap(this)->reportExtraMemoryCost(cost);
	}

	protected:
	void finishCreation(JSGlobalData& globalData)
	{
	Base::finishCreation(globalData);
	m_length = 0;
	m_is8Bit = true;
	}

	public:
	static JSString* create(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
	{
	ASSERT(value);
	size_t length = value->length();
	size_t cost = value->cost();
	JSString* newString = new (NotNull, allocateCell<JSString>(globalData.heap)) JSString(globalData, value);
	newString->finishCreation(globalData, length, cost);
	return newString;
	}
	static JSString* createHasOtherOwner(JSGlobalData& globalData, PassRefPtr<StringImpl> value)
	{
	ASSERT(value);
	size_t length = value->length();
	JSString* newString = new (NotNull, allocateCell<JSString>(globalData.heap)) JSString(globalData, value);
	newString->finishCreation(globalData, length);
	return newString;
	}

	const UString& value(ExecState*) const;
	const UString& tryGetValue() const;
	unsigned length() { return m_length; }

	JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
	JS_EXPORT_PRIVATE bool toBoolean(ExecState*) const;
	bool getPrimitiveNumber(ExecState*, double& number, JSValue&) const;
	JSObject* toObject(ExecState, JSGlobalObject) const;
	double toNumber(ExecState*) const;

	bool getStringPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
	bool getStringPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
	bool getStringPropertyDescriptor(ExecState*, const Identifier& propertyName, PropertyDescriptor&);

	bool canGetIndex(unsigned i) { return i < m_length; }
	JSString* getIndex(ExecState*, unsigned);

	static Structure* createStructure(JSGlobalData& globalData, JSGlobalObject* globalObject, JSValue proto)
	{
	return Structure::create(globalData, globalObject, proto, TypeInfo(StringType, OverridesGetOwnPropertySlot), &s_info);
	}

	static size_t offsetOfLength() { return OBJECT_OFFSETOF(JSString, m_length); }
	static size_t offsetOfValue() { return OBJECT_OFFSETOF(JSString, m_value); }

	static JS_EXPORTDATA const ClassInfo s_info;

	static void visitChildren(JSCell*, SlotVisitor&);

	protected:
	bool isRope() const { return m_value.isNull(); }
	bool is8Bit() const { return m_is8Bit; }

	// A string is represented either by a UString or a rope of fibers.
	bool m_is8Bit : 1;
	unsigned m_length;
	mutable UString m_value;

	private:
	friend class LLIntOffsetsExtractor;

	static JSObject* toThisObject(JSCell, ExecState);

	// Actually getPropertySlot, not getOwnPropertySlot (see JSCell).
	static bool getOwnPropertySlot(JSCell, ExecState, const Identifier& propertyName, PropertySlot&);
	static bool getOwnPropertySlotByIndex(JSCell, ExecState, unsigned propertyName, PropertySlot&);

	UString& string() { ASSERT(!isRope()); return m_value; }

	friend JSValue jsString(ExecState, JSString, JSString*);
	friend JSString* jsSubstring(ExecState, JSString, unsigned offset, unsigned length);
	};

	class JSRopeString : public JSString {
	friend class JSString;

	friend JSRopeString* jsStringBuilder(JSGlobalData*);

	class RopeBuilder {
	public:
	RopeBuilder(JSGlobalData& globalData)
	: m_globalData(globalData)
	, m_jsString(jsStringBuilder(&globalData))
	, m_index(0)
	{
	}

	void append(JSString* jsString)
	{
	if (m_index == JSRopeString::s_maxInternalRopeLength)
	expand();
	m_jsString->m_fibers[m_index++].set(m_globalData, m_jsString, jsString);
	m_jsString->m_length += jsString->m_length;
	m_jsString->m_is8Bit = m_jsString->m_is8Bit && jsString->m_is8Bit;
	}

	JSRopeString* release()
	{
	JSRopeString* tmp = m_jsString;
	m_jsString = 0;
	return tmp;
	}

	unsigned length() { return m_jsString->m_length; }

	private:
	void expand();

	JSGlobalData& m_globalData;
	JSRopeString* m_jsString;
	size_t m_index;
	};

	private:
	JSRopeString(JSGlobalData& globalData)
	: JSString(globalData)
	{
	}

	void finishCreation(JSGlobalData& globalData, JSString* s1, JSString* s2)
	{
	Base::finishCreation(globalData);
	m_length = s1->length() + s2->length();
	m_is8Bit = (s1->is8Bit() && s2->is8Bit());
	m_fibers[0].set(globalData, this, s1);
	m_fibers[1].set(globalData, this, s2);
	}

	void finishCreation(JSGlobalData& globalData, JSString* s1, JSString* s2, JSString* s3)
	{
	Base::finishCreation(globalData);
	m_length = s1->length() + s2->length() + s3->length();
	m_is8Bit = (s1->is8Bit() && s2->is8Bit() && s3->is8Bit());
	m_fibers[0].set(globalData, this, s1);
	m_fibers[1].set(globalData, this, s2);
	m_fibers[2].set(globalData, this, s3);
	}

	void finishCreation(JSGlobalData& globalData)
	{
	JSString::finishCreation(globalData);
	}

	static JSRopeString* createNull(JSGlobalData& globalData)
	{
	JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
	newString->finishCreation(globalData);
	return newString;
	}

	public:
	static JSString* create(JSGlobalData& globalData, JSString* s1, JSString* s2)
	{
	JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
	newString->finishCreation(globalData, s1, s2);
	return newString;
	}
	static JSString* create(JSGlobalData& globalData, JSString* s1, JSString* s2, JSString* s3)
	{
	JSRopeString* newString = new (NotNull, allocateCell<JSRopeString>(globalData.heap)) JSRopeString(globalData);
	newString->finishCreation(globalData, s1, s2, s3);
	return newString;
	}

	void visitFibers(SlotVisitor&);

	private:
	friend JSValue jsString(ExecState, Register, unsigned);
	friend JSValue jsStringFromArguments(ExecState*, JSValue);

	JS_EXPORT_PRIVATE void resolveRope(ExecState*) const;
	void resolveRopeSlowCase8(LChar*) const;
	void resolveRopeSlowCase(UChar*) const;
	void outOfMemory(ExecState*) const;

	JSString* getIndexSlowCase(ExecState*, unsigned);

	static const unsigned s_maxInternalRopeLength = 3;

	mutable FixedArray<WriteBarrier<JSString>, s_maxInternalRopeLength> m_fibers;
	};

	JSString* asString(JSValue);

	inline JSString* asString(JSValue value)
	{
	ASSERT(value.asCell()->isString());
	return jsCast<JSString*>(value.asCell());
	}

	inline JSString* jsEmptyString(JSGlobalData* globalData)
	{
	return globalData->smallStrings.emptyString(globalData);
	}

	inline JSString* jsSingleCharacterString(JSGlobalData* globalData, UChar c)
	{
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	return JSString::create(*globalData, UString(&c, 1).impl());
	}

	inline JSString* jsSingleCharacterSubstring(ExecState* exec, const UString& s, unsigned offset)
	{
	JSGlobalData* globalData = &exec->globalData();
	ASSERT(offset < static_cast<unsigned>(s.length()));
	UChar c = s[offset];
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	return JSString::create(*globalData, StringImpl::create(s.impl(), offset, 1));
	}

	inline JSString* jsNontrivialString(JSGlobalData* globalData, const char* s)
	{
	ASSERT(s);
	ASSERT(s[0]);
	ASSERT(s[1]);
	return JSString::create(*globalData, UString(s).impl());
	}

	inline JSString* jsNontrivialString(JSGlobalData* globalData, const UString& s)
	{
	ASSERT(s.length() > 1);
	return JSString::create(*globalData, s.impl());
	}

	inline const UString& JSString::value(ExecState* exec) const
	{
	if (isRope())
	static_cast<const JSRopeString*>(this)->resolveRope(exec);
	return m_value;
	}

	inline const UString& JSString::tryGetValue() const
	{
	if (isRope())
	static_cast<const JSRopeString*>(this)->resolveRope(0);
	return m_value;
	}

	inline JSString* JSString::getIndex(ExecState* exec, unsigned i)
	{
	ASSERT(canGetIndex(i));
	if (isRope())
	return static_cast<JSRopeString*>(this)->getIndexSlowCase(exec, i);
	ASSERT(i < m_value.length());
	return jsSingleCharacterSubstring(exec, m_value, i);
	}

	inline JSString* jsString(JSGlobalData* globalData, const UString& s)
	{
	int size = s.length();
	if (!size)
	return globalData->smallStrings.emptyString(globalData);
	if (size == 1) {
	UChar c = s[0];
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	}
	return JSString::create(*globalData, s.impl());
	}

	inline JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length)
	{
	ASSERT(offset <= static_cast<unsigned>(s->length()));
	ASSERT(length <= static_cast<unsigned>(s->length()));
	ASSERT(offset + length <= static_cast<unsigned>(s->length()));
	JSGlobalData* globalData = &exec->globalData();
	if (!length)
	return globalData->smallStrings.emptyString(globalData);
	return jsSubstring(globalData, s->value(exec), offset, length);
	}

	inline JSString* jsSubstring8(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
	{
	ASSERT(offset <= static_cast<unsigned>(s.length()));
	ASSERT(length <= static_cast<unsigned>(s.length()));
	ASSERT(offset + length <= static_cast<unsigned>(s.length()));
	if (!length)
	return globalData->smallStrings.emptyString(globalData);
	if (length == 1) {
	UChar c = s[offset];
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	}
	return JSString::createHasOtherOwner(*globalData, StringImpl::create8(s.impl(), offset, length));
	}

	inline JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
	{
	ASSERT(offset <= static_cast<unsigned>(s.length()));
	ASSERT(length <= static_cast<unsigned>(s.length()));
	ASSERT(offset + length <= static_cast<unsigned>(s.length()));
	if (!length)
	return globalData->smallStrings.emptyString(globalData);
	if (length == 1) {
	UChar c = s[offset];
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	}
	return JSString::createHasOtherOwner(*globalData, StringImpl::create(s.impl(), offset, length));
	}

	inline JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
	{
	int size = s.length();
	if (!size)
	return globalData->smallStrings.emptyString(globalData);
	if (size == 1) {
	UChar c = s[0];
	if (c <= maxSingleCharacterString)
	return globalData->smallStrings.singleCharacterString(globalData, c);
	}
	return JSString::createHasOtherOwner(*globalData, s.impl());
	}

	inline JSRopeString* jsStringBuilder(JSGlobalData* globalData)
	{
	return JSRopeString::createNull(*globalData);
	}

	inline JSString* jsEmptyString(ExecState* exec) { return jsEmptyString(&exec->globalData()); }
	inline JSString* jsString(ExecState* exec, const UString& s) { return jsString(&exec->globalData(), s); }
	inline JSString* jsSingleCharacterString(ExecState* exec, UChar c) { return jsSingleCharacterString(&exec->globalData(), c); }
	inline JSString* jsSubstring8(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring8(&exec->globalData(), s, offset, length); }
	inline JSString* jsSubstring(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring(&exec->globalData(), s, offset, length); }
	inline JSString* jsNontrivialString(ExecState* exec, const UString& s) { return jsNontrivialString(&exec->globalData(), s); }
	inline JSString* jsNontrivialString(ExecState* exec, const char* s) { return jsNontrivialString(&exec->globalData(), s); }
	inline JSString* jsOwnedString(ExecState* exec, const UString& s) { return jsOwnedString(&exec->globalData(), s); }

	ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
	{
	if (propertyName == exec->propertyNames().length) {
	slot.setValue(jsNumber(m_length));
	return true;
	}

	bool isStrictUInt32;
	unsigned i = propertyName.toUInt32(isStrictUInt32);
	if (isStrictUInt32 && i < m_length) {
	slot.setValue(getIndex(exec, i));
	return true;
	}

	return false;
	}

	ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
	{
	if (propertyName < m_length) {
	slot.setValue(getIndex(exec, propertyName));
	return true;
	}

	return false;
	}

	inline bool isJSString(JSValue v) { return v.isCell() && v.asCell()->classInfo() == &JSString::s_info; }

	inline bool JSCell::toBoolean(ExecState* exec) const
	{
	if (isString())
	return static_cast<const JSString*>(this)->toBoolean(exec);
	return !structure()->typeInfo().masqueradesAsUndefined();
	}

	// --- JSValue inlines ----------------------------

	inline bool JSValue::toBoolean(ExecState* exec) const
	{
	if (isInt32())
	return asInt32();
	if (isDouble())
	return asDouble() > 0.0 \|\| asDouble() < 0.0; // false for NaN
	if (isCell())
	return asCell()->toBoolean(exec);
	return isTrue(); // false, null, and undefined all convert to false.
	}

	inline JSString* JSValue::toString(ExecState* exec) const
	{
	if (isString())
	return jsCast<JSString*>(asCell());
	return toStringSlowCase(exec);
	}

	inline UString JSValue::toUString(ExecState* exec) const
	{
	if (isString())
	return static_cast<JSString*>(asCell())->value(exec);
	return toUStringSlowCase(exec);
	}

	ALWAYS_INLINE UString inlineJSValueNotStringtoUString(const JSValue& value, ExecState* exec)
	{
	JSGlobalData& globalData = exec->globalData();
	if (value.isInt32())
	return globalData.numericStrings.add(value.asInt32());
	if (value.isDouble())
	return globalData.numericStrings.add(value.asDouble());
	if (value.isTrue())
	return globalData.propertyNames->trueKeyword.ustring();
	if (value.isFalse())
	return globalData.propertyNames->falseKeyword.ustring();
	if (value.isNull())
	return globalData.propertyNames->nullKeyword.ustring();
	if (value.isUndefined())
	return globalData.propertyNames->undefinedKeyword.ustring();
	return value.toString(exec)->value(exec);
	}

	ALWAYS_INLINE UString JSValue::toUStringInline(ExecState* exec) const
	{
	if (isString())
	return static_cast<JSString*>(asCell())->value(exec);

	return inlineJSValueNotStringtoUString(*this, exec);
	}

	} // namespace JSC

	#endif // JSString_h