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 final : public JSCell {
  44     friend class JIT;
  45
  46 public:
  47     typedef JSCell Base;
  48     static const unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
  49
  50     static StructureChain* create(VM& vm, Structure* head)
  51     {
  52         StructureChain* chain = new (NotNull, allocateCell<StructureChain>(vm.heap)) StructureChain(vm, vm.structureChainStructure.get());
  53         chain->finishCreation(vm, head);
  54         return chain;
  55     }
  56     WriteBarrier<Structure>* head() { return m_vector.get(); }
  57     static void visitChildren(JSCell*, SlotVisitor&);
  58
  59     static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
  60     {
  61         return Structure::create(vm, globalObject, prototype, TypeInfo(CellType, StructureFlags), info());
  62     }
  63
  64     DECLARE_INFO;
  65
  66     static const bool needsDestruction = true;
  67     static void destroy(JSCell*);
  68
  69 protected:
  70     void finishCreation(VM& vm, Structure* head)
  71     {
  72         Base::finishCreation(vm);
  73         size_t size = 0;
  74         for (Structure* current = head; current; current = current->storedPrototype().isNull() ? 0 : asObject(current->storedPrototype())->structure())
  75             ++size;
  76
  77         m_vector = std::make_unique<WriteBarrier<Structure>[]>(size + 1);
  78
  79         size_t i = 0;
  80         for (Structure* current = head; current; current = current->storedPrototype().isNull() ? 0 : asObject(current->storedPrototype())->structure())
  81             m_vector[i++].set(vm, this, current);
  82     }
  83
  84 private:
  85     friend class LLIntOffsetsExtractor;
  86
  87     StructureChain(VM&, Structure*);
  88     std::unique_ptr<WriteBarrier<Structure>[]> m_vector;
  89 };
  90
  91 } // namespace JSC
  92
  93 #endif // StructureChain_h