runtime/JSPropertyNameEnumerator.h

   1 /*
   2  * Copyright (C) 2014 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef JSPropertyNameEnumerator_h
  27 #define JSPropertyNameEnumerator_h
  28
  29 #include "JSCell.h"
  30 #include "Operations.h"
  31 #include "PropertyNameArray.h"
  32 #include "Structure.h"
  33
  34 namespace JSC {
  35
  36 class Identifier;
  37
  38 class JSPropertyNameEnumerator final : public JSCell {
  39 public:
  40     typedef JSCell Base;
  41     static const unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
  42
  43     static JSPropertyNameEnumerator* create(VM&);
  44     static JSPropertyNameEnumerator* create(VM&, Structure*, uint32_t, uint32_t, PropertyNameArray&);
  45
  46     static const bool needsDestruction = true;
  47     static void destroy(JSCell*);
  48
  49     static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
  50     {
  51         return Structure::create(vm, globalObject, prototype, TypeInfo(CellType, StructureFlags), info());
  52     }
  53
  54     DECLARE_EXPORT_INFO;
  55
  56     JSString* propertyNameAtIndex(uint32_t index) const
  57     {
  58         if (index >= m_propertyNames.size())
  59             return nullptr;
  60         return m_propertyNames[index].get();
  61     }
  62
  63     StructureChain* cachedPrototypeChain() const { return m_prototypeChain.get(); }
  64     void setCachedPrototypeChain(VM& vm, StructureChain* prototypeChain) { return m_prototypeChain.set(vm, this, prototypeChain); }
  65
  66     Structure* cachedStructure(VM& vm) const
  67     {
  68         if (!m_cachedStructureID)
  69             return nullptr;
  70         return vm.heap.structureIDTable().get(m_cachedStructureID);
  71     }
  72     StructureID cachedStructureID() const { return m_cachedStructureID; }
  73     uint32_t indexedLength() const { return m_indexedLength; }
  74     uint32_t endStructurePropertyIndex() const { return m_endStructurePropertyIndex; }
  75     uint32_t endGenericPropertyIndex() const { return m_endGenericPropertyIndex; }
  76     uint32_t cachedInlineCapacity() const { return m_cachedInlineCapacity; }
  77     static ptrdiff_t cachedStructureIDOffset() { return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_cachedStructureID); }
  78     static ptrdiff_t indexedLengthOffset() { return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_indexedLength); }
  79     static ptrdiff_t endStructurePropertyIndexOffset() { return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_endStructurePropertyIndex); }
  80     static ptrdiff_t endGenericPropertyIndexOffset() { return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_endGenericPropertyIndex); }
  81     static ptrdiff_t cachedInlineCapacityOffset() { return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_cachedInlineCapacity); }
  82     static ptrdiff_t cachedPropertyNamesVectorOffset()
  83     {
  84         return OBJECT_OFFSETOF(JSPropertyNameEnumerator, m_propertyNames) + Vector<WriteBarrier<JSString>>::dataMemoryOffset();
  85     }
  86
  87     static void visitChildren(JSCell*, SlotVisitor&);
  88
  89 private:
  90     JSPropertyNameEnumerator(VM&, StructureID, uint32_t);
  91     void finishCreation(VM&, uint32_t, uint32_t, PassRefPtr<PropertyNameArrayData>);
  92
  93     Vector<WriteBarrier<JSString>> m_propertyNames;
  94     StructureID m_cachedStructureID;
  95     WriteBarrier<StructureChain> m_prototypeChain;
  96     uint32_t m_indexedLength;
  97     uint32_t m_endStructurePropertyIndex;
  98     uint32_t m_endGenericPropertyIndex;
  99     uint32_t m_cachedInlineCapacity;
 100 };
 101
 102 inline JSPropertyNameEnumerator* propertyNameEnumerator(ExecState* exec, JSObject* base)
 103 {
 104     VM& vm = exec->vm();
 105
 106     uint32_t indexedLength = base->methodTable(vm)->getEnumerableLength(exec, base);
 107
 108     JSPropertyNameEnumerator* enumerator = nullptr;
 109
 110     Structure* structure = base->structure(vm);
 111     if (!indexedLength
 112         && (enumerator = structure->cachedPropertyNameEnumerator())
 113         && enumerator->cachedPrototypeChain() == structure->prototypeChain(exec))
 114         return enumerator;
 115
 116     uint32_t numberStructureProperties = 0;
 117
 118     PropertyNameArray propertyNames(exec);
 119
 120     if (structure->canAccessPropertiesQuickly() && indexedLength == base->getArrayLength()) {
 121         base->methodTable(vm)->getStructurePropertyNames(base, exec, propertyNames, EnumerationMode());
 122
 123         numberStructureProperties = propertyNames.size();
 124
 125         base->methodTable(vm)->getGenericPropertyNames(base, exec, propertyNames, EnumerationMode());
 126     } else
 127         base->methodTable(vm)->getPropertyNames(base, exec, propertyNames, EnumerationMode());
 128
 129     ASSERT(propertyNames.size() < UINT32_MAX);
 130
 131     normalizePrototypeChain(exec, structure);
 132
 133     enumerator = JSPropertyNameEnumerator::create(vm, structure, indexedLength, numberStructureProperties, propertyNames);
 134     enumerator->setCachedPrototypeChain(vm, structure->prototypeChain(exec));
 135     if (!indexedLength && structure->canCachePropertyNameEnumerator())
 136         structure->setCachedPropertyNameEnumerator(vm, enumerator);
 137     return enumerator;
 138 }
 139
 140 } // namespace JSC
 141
 142 #endif // JSPropertyNameEnumerator_h