runtime/JSArray.h

   1 /*
   2  *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
   3  *  Copyright (C) 2003, 2007, 2008, 2009 Apple Inc. All rights reserved.
   4  *
   5  *  This library is free software; you can redistribute it and/or
   6  *  modify it under the terms of the GNU Lesser General Public
   7  *  License as published by the Free Software Foundation; either
   8  *  version 2 of the License, or (at your option) any later version.
   9  *
  10  *  This library is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  Lesser General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU Lesser General Public
  16  *  License along with this library; if not, write to the Free Software
  17  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  18  *
  19  */
  20
  21 #ifndef JSArray_h
  22 #define JSArray_h
  23
  24 #include "JSObject.h"
  25
  26 #define CHECK_ARRAY_CONSISTENCY 0
  27
  28 namespace JSC {
  29
  30     typedef HashMap<unsigned, WriteBarrier<Unknown> > SparseArrayValueMap;
  31
  32     // This struct holds the actual data values of an array.  A JSArray object points to it's contained ArrayStorage
  33     // struct by pointing to m_vector.  To access the contained ArrayStorage struct, use the getStorage() and
  34     // setStorage() methods.  It is important to note that there may be space before the ArrayStorage that
  35     // is used to quick unshift / shift operation.  The actual allocated pointer is available by using:
  36     //     getStorage() - m_indexBias * sizeof(JSValue)
  37     struct ArrayStorage {
  38         unsigned m_length; // The "length" property on the array
  39         unsigned m_numValuesInVector;
  40         SparseArrayValueMap* m_sparseValueMap;
  41         void* subclassData; // A JSArray subclass can use this to fill the vector lazily.
  42         void* m_allocBase; // Pointer to base address returned by malloc().  Keeping this pointer does eliminate false positives from the leak detector.
  43         size_t reportedMapCapacity;
  44 #if CHECK_ARRAY_CONSISTENCY
  45         bool m_inCompactInitialization;
  46 #endif
  47         WriteBarrier<Unknown> m_vector[1];
  48     };
  49
  50     // The CreateCompact creation mode is used for fast construction of arrays
  51     // whose size and contents are known at time of creation.
  52     //
  53     // There are two obligations when using this mode:
  54     //
  55     //   - uncheckedSetIndex() must be used when initializing the array.
  56     //   - setLength() must be called after initialization.
  57
  58     enum ArrayCreationMode { CreateCompact, CreateInitialized };
  59
  60     class JSArray : public JSNonFinalObject {
  61         friend class Walker;
  62
  63     public:
  64         JSArray(VPtrStealingHackType);
  65
  66         explicit JSArray(JSGlobalData&, Structure*);
  67         JSArray(JSGlobalData&, Structure*, unsigned initialLength, ArrayCreationMode);
  68         JSArray(JSGlobalData&, Structure*, const ArgList& initialValues);
  69         virtual ~JSArray();
  70
  71         virtual bool getOwnPropertySlot(ExecState*, const Identifier& propertyName, PropertySlot&);
  72         virtual bool getOwnPropertySlot(ExecState*, unsigned propertyName, PropertySlot&);
  73         virtual bool getOwnPropertyDescriptor(ExecState*, const Identifier&, PropertyDescriptor&);
  74         virtual void put(ExecState*, unsigned propertyName, JSValue); // FIXME: Make protected and add setItem.
  75
  76         static JS_EXPORTDATA const ClassInfo s_info;
  77
  78         unsigned length() const { return m_storage->m_length; }
  79         void setLength(unsigned); // OK to use on new arrays, but not if it might be a RegExpMatchArray.
  80
  81         void sort(ExecState*);
  82         void sort(ExecState*, JSValue compareFunction, CallType, const CallData&);
  83         void sortNumeric(ExecState*, JSValue compareFunction, CallType, const CallData&);
  84
  85         void push(ExecState*, JSValue);
  86         JSValue pop();
  87
  88         void shiftCount(ExecState*, int count);
  89         void unshiftCount(ExecState*, int count);
  90
  91         bool canGetIndex(unsigned i) { return i < m_vectorLength && m_storage->m_vector[i]; }
  92         JSValue getIndex(unsigned i)
  93         {
  94             ASSERT(canGetIndex(i));
  95             return m_storage->m_vector[i].get();
  96         }
  97
  98         bool canSetIndex(unsigned i) { return i < m_vectorLength; }
  99         void setIndex(JSGlobalData& globalData, unsigned i, JSValue v)
 100         {
 101             ASSERT(canSetIndex(i));
 102
 103             WriteBarrier<Unknown>& x = m_storage->m_vector[i];
 104             if (!x) {
 105                 ArrayStorage *storage = m_storage;
 106                 ++storage->m_numValuesInVector;
 107                 if (i >= storage->m_length)
 108                     storage->m_length = i + 1;
 109             }
 110             x.set(globalData, this, v);
 111         }
 112
 113         void uncheckedSetIndex(JSGlobalData& globalData, unsigned i, JSValue v)
 114         {
 115             ASSERT(canSetIndex(i));
 116             ArrayStorage *storage = m_storage;
 117 #if CHECK_ARRAY_CONSISTENCY
 118             ASSERT(storage->m_inCompactInitialization);
 119 #endif
 120             storage->m_vector[i].set(globalData, this, v);
 121         }
 122
 123         void fillArgList(ExecState*, MarkedArgumentBuffer&);
 124         void copyToRegisters(ExecState*, Register*, uint32_t);
 125
 126         static Structure* createStructure(JSGlobalData& globalData, JSValue prototype)
 127         {
 128             return Structure::create(globalData, prototype, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount, &s_info);
 129         }
 130
 131         inline void visitChildrenDirect(SlotVisitor&);
 132
 133         static ptrdiff_t storageOffset()
 134         {
 135             return OBJECT_OFFSETOF(JSArray, m_storage);
 136         }
 137
 138         static ptrdiff_t vectorLengthOffset()
 139         {
 140             return OBJECT_OFFSETOF(JSArray, m_vectorLength);
 141         }
 142
 143     protected:
 144         static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesVisitChildren | OverridesGetPropertyNames | JSObject::StructureFlags;
 145         virtual void put(ExecState*, const Identifier& propertyName, JSValue, PutPropertySlot&);
 146         virtual bool deleteProperty(ExecState*, const Identifier& propertyName);
 147         virtual bool deleteProperty(ExecState*, unsigned propertyName);
 148         virtual void getOwnPropertyNames(ExecState*, PropertyNameArray&, EnumerationMode mode = ExcludeDontEnumProperties);
 149         virtual void visitChildren(SlotVisitor&);
 150
 151         void* subclassData() const;
 152         void setSubclassData(void*);
 153
 154     private:
 155         bool getOwnPropertySlotSlowCase(ExecState*, unsigned propertyName, PropertySlot&);
 156         void putSlowCase(ExecState*, unsigned propertyName, JSValue);
 157
 158         unsigned getNewVectorLength(unsigned desiredLength);
 159         bool increaseVectorLength(unsigned newLength);
 160         bool increaseVectorPrefixLength(unsigned newLength);
 161
 162         unsigned compactForSorting();
 163
 164         enum ConsistencyCheckType { NormalConsistencyCheck, DestructorConsistencyCheck, SortConsistencyCheck };
 165         void checkConsistency(ConsistencyCheckType = NormalConsistencyCheck);
 166
 167         unsigned m_vectorLength; // The valid length of m_vector
 168         int m_indexBias; // The number of JSValue sized blocks before ArrayStorage.
 169         ArrayStorage *m_storage;
 170     };
 171
 172     JSArray* asArray(JSValue);
 173
 174     inline JSArray* asArray(JSCell* cell)
 175     {
 176         ASSERT(cell->inherits(&JSArray::s_info));
 177         return static_cast<JSArray*>(cell);
 178     }
 179
 180     inline JSArray* asArray(JSValue value)
 181     {
 182         return asArray(value.asCell());
 183     }
 184
 185     inline bool isJSArray(JSGlobalData* globalData, JSCell* cell) { return cell->vptr() == globalData->jsArrayVPtr; }
 186     inline bool isJSArray(JSGlobalData* globalData, JSValue v) { return v.isCell() && isJSArray(globalData, v.asCell()); }
 187
 188     inline void JSArray::visitChildrenDirect(SlotVisitor& visitor)
 189     {
 190         JSObject::visitChildrenDirect(visitor);
 191
 192         ArrayStorage* storage = m_storage;
 193
 194         unsigned usedVectorLength = std::min(storage->m_length, m_vectorLength);
 195         visitor.appendValues(storage->m_vector, usedVectorLength, MayContainNullValues);
 196
 197         if (SparseArrayValueMap* map = storage->m_sparseValueMap) {
 198             SparseArrayValueMap::iterator end = map->end();
 199             for (SparseArrayValueMap::iterator it = map->begin(); it != end; ++it)
 200                 visitor.append(&it->second);
 201         }
 202     }
 203
 204     // Rule from ECMA 15.2 about what an array index is.
 205     // Must exactly match string form of an unsigned integer, and be less than 2^32 - 1.
 206     inline unsigned Identifier::toArrayIndex(bool& ok) const
 207     {
 208         unsigned i = toUInt32(ok);
 209         if (ok && i >= 0xFFFFFFFFU)
 210             ok = false;
 211         return i;
 212     }
 213
 214 } // namespace JSC
 215
 216 #endif // JSArray_h