JSString.h revision 2bde8e466a4451c7319e3a072d118917957d6554 
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
34namespace 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.impl());
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                StringImpl* 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<StringImpl*>(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.length())
190            , m_value(value)
191            , m_fiberCount(0)
192        {
193            ASSERT(!m_value.isNull());
194            Heap::heap(this)->reportExtraMemoryCost(value.impl()->cost());
195        }
196
197        enum HasOtherOwnerType { HasOtherOwner };
198        JSString(JSGlobalData* globalData, const UString& value, HasOtherOwnerType)
199            : JSCell(globalData->stringStructure.get())
200            , m_length(value.length())
201            , m_value(value)
202            , m_fiberCount(0)
203        {
204            ASSERT(!m_value.isNull());
205        }
206        JSString(JSGlobalData* globalData, PassRefPtr<StringImpl> 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.leakRef();
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.length())
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.length() + 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.length() + u2.length())
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.length() + u2.length() + u3.length())
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.length())
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.impl()->cost());
312        }
313
314        ~JSString()
315        {
316            ASSERT(vptr() == JSGlobalData::jsStringVPtr);
317            if (!m_fiberCount) {
318                if (m_other.m_finalizerCallback)
319                    m_other.m_finalizerCallback(this, m_other.m_finalizerContext);
320            } else {
321                unsigned i = 0;
322                do
323                    RopeImpl::deref(m_other.m_fibers[i]);
324                while (++i < m_fiberCount);
325            }
326        }
327
328        const UString& value(ExecState* exec) const
329        {
330            if (isRope())
331                resolveRope(exec);
332            return m_value;
333        }
334        const UString& tryGetValue() const
335        {
336            if (isRope())
337                resolveRope(0);
338            return m_value;
339        }
340        unsigned length() { return m_length; }
341
342        bool getStringPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
343        bool getStringPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
344        bool getStringPropertyDescriptor(ExecState*, const Identifier& propertyName, PropertyDescriptor&);
345
346        bool canGetIndex(unsigned i) { return i < m_length; }
347        JSString* getIndex(ExecState*, unsigned);
348        JSString* getIndexSlowCase(ExecState*, unsigned);
349
350        JSValue replaceCharacter(ExecState*, UChar, const UString& replacement);
351
352        static PassRefPtr<Structure> createStructure(JSGlobalData& globalData, JSValue proto) { return Structure::create(globalData, proto, TypeInfo(StringType, OverridesGetOwnPropertySlot | NeedsThisConversion), AnonymousSlotCount, 0); }
353
354    private:
355        enum VPtrStealingHackType { VPtrStealingHack };
356        JSString(VPtrStealingHackType)
357            : JSCell(0)
358            , m_fiberCount(0)
359        {
360        }
361
362        void resolveRope(ExecState*) const;
363        JSString* substringFromRope(ExecState*, unsigned offset, unsigned length);
364
365        void appendStringInConstruct(unsigned& index, const UString& string)
366        {
367            StringImpl* impl = string.impl();
368            impl->ref();
369            m_other.m_fibers[index++] = impl;
370        }
371
372        void appendStringInConstruct(unsigned& index, JSString* jsString)
373        {
374            if (jsString->isRope()) {
375                for (unsigned i = 0; i < jsString->m_fiberCount; ++i) {
376                    RopeImpl::Fiber fiber = jsString->m_other.m_fibers[i];
377                    fiber->ref();
378                    m_other.m_fibers[index++] = fiber;
379                }
380            } else
381                appendStringInConstruct(index, jsString->string());
382        }
383
384        void appendValueInConstructAndIncrementLength(ExecState* exec, unsigned& index, JSValue v)
385        {
386            if (v.isString()) {
387                ASSERT(v.asCell()->isString());
388                JSString* s = static_cast<JSString*>(v.asCell());
389                ASSERT(s->fiberCount() == 1);
390                appendStringInConstruct(index, s);
391                m_length += s->length();
392            } else {
393                UString u(v.toString(exec));
394                StringImpl* impl = u.impl();
395                impl->ref();
396                m_other.m_fibers[index++] = impl;
397                m_length += u.length();
398            }
399        }
400
401        virtual JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
402        virtual bool getPrimitiveNumber(ExecState*, double& number, JSValue& value);
403        virtual bool toBoolean(ExecState*) const;
404        virtual double toNumber(ExecState*) const;
405        virtual JSObject* toObject(ExecState*, JSGlobalObject*) const;
406        virtual UString toString(ExecState*) const;
407
408        virtual JSObject* toThisObject(ExecState*) const;
409
410        // Actually getPropertySlot, not getOwnPropertySlot (see JSCell).
411        virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
412        virtual bool getOwnPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
413        virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);
414
415        static const unsigned s_maxInternalRopeLength = 3;
416
417        // A string is represented either by a UString or a RopeImpl.
418        unsigned m_length;
419        mutable UString m_value;
420        mutable unsigned m_fiberCount;
421        // This structure exists to support a temporary workaround for a GC issue.
422        struct JSStringFinalizerStruct {
423            JSStringFinalizerStruct() : m_finalizerCallback(0) {}
424            union {
425                mutable FixedArray<RopeImpl::Fiber, s_maxInternalRopeLength> m_fibers;
426                struct {
427                    JSStringFinalizerCallback m_finalizerCallback;
428                    void* m_finalizerContext;
429                };
430            };
431        } m_other;
432
433        bool isRope() const { return m_fiberCount; }
434        UString& string() { ASSERT(!isRope()); return m_value; }
435        unsigned fiberCount() { return m_fiberCount ? m_fiberCount : 1; }
436
437        friend JSValue jsString(ExecState* exec, JSString* s1, JSString* s2);
438        friend JSValue jsString(ExecState* exec, const UString& u1, JSString* s2);
439        friend JSValue jsString(ExecState* exec, JSString* s1, const UString& u2);
440        friend JSValue jsString(ExecState* exec, Register* strings, unsigned count);
441        friend JSValue jsString(ExecState* exec, JSValue thisValue);
442        friend JSString* jsStringWithFinalizer(ExecState*, const UString&, JSStringFinalizerCallback callback, void* context);
443        friend JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length);
444    };
445
446    JSString* asString(JSValue);
447
448    // When an object is created from a different DLL, MSVC changes vptr to a "local" one right after invoking a constructor,
449    // see <http://groups.google.com/group/microsoft.public.vc.language/msg/55cdcefeaf770212>.
450    // This breaks isJSString(), and we don't need that hack anyway, so we change vptr back to primary one.
451    // The below function must be called by any inline function that invokes a JSString constructor.
452#if COMPILER(MSVC) && !defined(BUILDING_JavaScriptCore)
453    inline JSString* fixupVPtr(JSGlobalData* globalData, JSString* string) { string->setVPtr(globalData->jsStringVPtr); return string; }
454#else
455    inline JSString* fixupVPtr(JSGlobalData*, JSString* string) { return string; }
456#endif
457
458    inline JSString* asString(JSValue value)
459    {
460        ASSERT(value.asCell()->isString());
461        return static_cast<JSString*>(value.asCell());
462    }
463
464    inline JSString* jsEmptyString(JSGlobalData* globalData)
465    {
466        return globalData->smallStrings.emptyString(globalData);
467    }
468
469    inline JSString* jsSingleCharacterString(JSGlobalData* globalData, UChar c)
470    {
471        if (c <= maxSingleCharacterString)
472            return globalData->smallStrings.singleCharacterString(globalData, c);
473        return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(&c, 1)));
474    }
475
476    inline JSString* jsSingleCharacterSubstring(ExecState* exec, const UString& s, unsigned offset)
477    {
478        JSGlobalData* globalData = &exec->globalData();
479        ASSERT(offset < static_cast<unsigned>(s.length()));
480        UChar c = s.characters()[offset];
481        if (c <= maxSingleCharacterString)
482            return globalData->smallStrings.singleCharacterString(globalData, c);
483        return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(StringImpl::create(s.impl(), offset, 1))));
484    }
485
486    inline JSString* jsNontrivialString(JSGlobalData* globalData, const char* s)
487    {
488        ASSERT(s);
489        ASSERT(s[0]);
490        ASSERT(s[1]);
491        return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
492    }
493
494    inline JSString* jsNontrivialString(JSGlobalData* globalData, const UString& s)
495    {
496        ASSERT(s.length() > 1);
497        return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
498    }
499
500    inline JSString* JSString::getIndex(ExecState* exec, unsigned i)
501    {
502        ASSERT(canGetIndex(i));
503        if (isRope())
504            return getIndexSlowCase(exec, i);
505        ASSERT(i < m_value.length());
506        return jsSingleCharacterSubstring(exec, m_value, i);
507    }
508
509    inline JSString* jsString(JSGlobalData* globalData, const UString& s)
510    {
511        int size = s.length();
512        if (!size)
513            return globalData->smallStrings.emptyString(globalData);
514        if (size == 1) {
515            UChar c = s.characters()[0];
516            if (c <= maxSingleCharacterString)
517                return globalData->smallStrings.singleCharacterString(globalData, c);
518        }
519        return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
520    }
521
522    inline JSString* jsStringWithFinalizer(ExecState* exec, const UString& s, JSStringFinalizerCallback callback, void* context)
523    {
524        ASSERT(s.length() && (s.length() > 1 || s.characters()[0] > maxSingleCharacterString));
525        JSGlobalData* globalData = &exec->globalData();
526        return fixupVPtr(globalData, new (globalData) JSString(globalData, s, callback, context));
527    }
528
529    inline JSString* jsSubstring(ExecState* exec, JSString* s, unsigned offset, unsigned length)
530    {
531        ASSERT(offset <= static_cast<unsigned>(s->length()));
532        ASSERT(length <= static_cast<unsigned>(s->length()));
533        ASSERT(offset + length <= static_cast<unsigned>(s->length()));
534        JSGlobalData* globalData = &exec->globalData();
535        if (!length)
536            return globalData->smallStrings.emptyString(globalData);
537        if (s->isRope())
538            return s->substringFromRope(exec, offset, length);
539        return jsSubstring(globalData, s->m_value, offset, length);
540    }
541
542    inline JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
543    {
544        ASSERT(offset <= static_cast<unsigned>(s.length()));
545        ASSERT(length <= static_cast<unsigned>(s.length()));
546        ASSERT(offset + length <= static_cast<unsigned>(s.length()));
547        if (!length)
548            return globalData->smallStrings.emptyString(globalData);
549        if (length == 1) {
550            UChar c = s.characters()[offset];
551            if (c <= maxSingleCharacterString)
552                return globalData->smallStrings.singleCharacterString(globalData, c);
553        }
554        return fixupVPtr(globalData, new (globalData) JSString(globalData, UString(StringImpl::create(s.impl(), offset, length)), JSString::HasOtherOwner));
555    }
556
557    inline JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
558    {
559        int size = s.length();
560        if (!size)
561            return globalData->smallStrings.emptyString(globalData);
562        if (size == 1) {
563            UChar c = s.characters()[0];
564            if (c <= maxSingleCharacterString)
565                return globalData->smallStrings.singleCharacterString(globalData, c);
566        }
567        return fixupVPtr(globalData, new (globalData) JSString(globalData, s, JSString::HasOtherOwner));
568    }
569
570    inline JSString* jsEmptyString(ExecState* exec) { return jsEmptyString(&exec->globalData()); }
571    inline JSString* jsString(ExecState* exec, const UString& s) { return jsString(&exec->globalData(), s); }
572    inline JSString* jsSingleCharacterString(ExecState* exec, UChar c) { return jsSingleCharacterString(&exec->globalData(), c); }
573    inline JSString* jsSubstring(ExecState* exec, const UString& s, unsigned offset, unsigned length) { return jsSubstring(&exec->globalData(), s, offset, length); }
574    inline JSString* jsNontrivialString(ExecState* exec, const UString& s) { return jsNontrivialString(&exec->globalData(), s); }
575    inline JSString* jsNontrivialString(ExecState* exec, const char* s) { return jsNontrivialString(&exec->globalData(), s); }
576    inline JSString* jsOwnedString(ExecState* exec, const UString& s) { return jsOwnedString(&exec->globalData(), s); }
577
578    ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
579    {
580        if (propertyName == exec->propertyNames().length) {
581            slot.setValue(jsNumber(m_length));
582            return true;
583        }
584
585        bool isStrictUInt32;
586        unsigned i = propertyName.toUInt32(isStrictUInt32);
587        if (isStrictUInt32 && i < m_length) {
588            slot.setValue(getIndex(exec, i));
589            return true;
590        }
591
592        return false;
593    }
594
595    ALWAYS_INLINE bool JSString::getStringPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
596    {
597        if (propertyName < m_length) {
598            slot.setValue(getIndex(exec, propertyName));
599            return true;
600        }
601
602        return false;
603    }
604
605    inline bool isJSString(JSGlobalData* globalData, JSValue v) { return v.isCell() && v.asCell()->vptr() == globalData->jsStringVPtr; }
606
607    // --- JSValue inlines ----------------------------
608
609    inline UString JSValue::toString(ExecState* exec) const
610    {
611        if (isString())
612            return static_cast<JSString*>(asCell())->value(exec);
613        if (isInt32())
614            return exec->globalData().numericStrings.add(asInt32());
615        if (isDouble())
616            return exec->globalData().numericStrings.add(asDouble());
617        if (isTrue())
618            return "true";
619        if (isFalse())
620            return "false";
621        if (isNull())
622            return "null";
623        if (isUndefined())
624            return "undefined";
625        ASSERT(isCell());
626        return asCell()->toString(exec);
627    }
628
629    inline UString JSValue::toPrimitiveString(ExecState* exec) const
630    {
631        ASSERT(!isString());
632        if (isInt32())
633            return exec->globalData().numericStrings.add(asInt32());
634        if (isDouble())
635            return exec->globalData().numericStrings.add(asDouble());
636        if (isTrue())
637            return "true";
638        if (isFalse())
639            return "false";
640        if (isNull())
641            return "null";
642        if (isUndefined())
643            return "undefined";
644        ASSERT(isCell());
645        return asCell()->toPrimitive(exec, NoPreference).toString(exec);
646    }
647
648} // namespace JSC
649
650#endif // JSString_h
651