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