runtime/StructureChain.h

   1 /*
   2  * Copyright (C) 2008 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. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef StructureChain_h
  27 #define StructureChain_h
  28
  29 #include "JSCell.h"
  30 #include "JSObject.h"
  31 #include "Structure.h"
  32
  33 #include <wtf/PassRefPtr.h>
  34 #include <wtf/RefCounted.h>
  35 #include <wtf/RefPtr.h>
  36 #include <wtf/StdLibExtras.h>
  37
  38 namespace JSC {
  39
  40     class LLIntOffsetsExtractor;
  41     class Structure;
  42
  43     class StructureChain : public JSCell {
  44         friend class JIT;
  45
  46     public:
  47         typedef JSCell Base;
  48
  49         static StructureChain* create(VM& vm, Structure* head)
  50         {
  51             StructureChain* chain = new (NotNull, allocateCell<StructureChain>(vm.heap)) StructureChain(vm, vm.structureChainStructure.get());
  52             chain->finishCreation(vm, head);
  53             return chain;
  54         }
  55         WriteBarrier<Structure>* head() { return m_vector.get(); }
  56         static void visitChildren(JSCell*, SlotVisitor&);
  57
  58         static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
  59         {
  60             return Structure::create(vm, globalObject, prototype, TypeInfo(CompoundType, StructureFlags), info());
  61         }
  62
  63         DECLARE_INFO;
  64
  65         static const bool needsDestruction = true;
  66         static const bool hasImmortalStructure = true;
  67         static void destroy(JSCell*);
  68
  69     protected:
  70         static const unsigned StructureFlags = OverridesVisitChildren | StructureIsImmortal;
  71
  72         void finishCreation(VM& vm, Structure* head)
  73         {
  74             Base::finishCreation(vm);
  75             size_t size = 0;
  76             for (Structure* current = head; current; current = current->storedPrototype().isNull() ? 0 : asObject(current->storedPrototype())->structure())
  77                 ++size;
  78
  79             m_vector = std::make_unique<WriteBarrier<Structure>[]>(size + 1);
  80
  81             size_t i = 0;
  82             for (Structure* current = head; current; current = current->storedPrototype().isNull() ? 0 : asObject(current->storedPrototype())->structure())
  83                 m_vector[i++].set(vm, this, current);
  84         }
  85
  86     private:
  87         friend class LLIntOffsetsExtractor;
  88
  89         StructureChain(VM&, Structure*);
  90         std::unique_ptr<WriteBarrier<Structure>[]> m_vector;
  91     };
  92
  93 } // namespace JSC
  94
  95 #endif // StructureChain_h