runtime/ScopeChain.h

   1 /*
   2  *  Copyright (C) 2003, 2008, 2009 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #ifndef ScopeChain_h
  22 #define ScopeChain_h
  23
  24 #include "JSCell.h"
  25 #include "Structure.h"
  26 #include <wtf/FastAllocBase.h>
  27
  28 namespace JSC {
  29
  30     class JSGlobalData;
  31     class JSGlobalObject;
  32     class JSObject;
  33     class MarkStack;
  34     class ScopeChainIterator;
  35     typedef MarkStack SlotVisitor;
  36
  37     class ScopeChainNode : public JSCell {
  38     public:
  39         ScopeChainNode(ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis)
  40             : JSCell(*globalData, globalData->scopeChainNodeStructure.get())
  41             , globalData(globalData)
  42             , next(*globalData, this, next, WriteBarrier<ScopeChainNode>::MayBeNull)
  43             , object(*globalData, this, object)
  44             , globalObject(*globalData, this, globalObject)
  45             , globalThis(*globalData, this, globalThis)
  46         {
  47             ASSERT(globalData);
  48             ASSERT(globalObject);
  49         }
  50
  51         JSGlobalData* globalData;
  52         WriteBarrier<ScopeChainNode> next;
  53         WriteBarrier<JSObject> object;
  54         WriteBarrier<JSGlobalObject> globalObject;
  55         WriteBarrier<JSObject> globalThis;
  56
  57         ScopeChainNode* push(JSObject*);
  58         ScopeChainNode* pop();
  59
  60         ScopeChainIterator begin();
  61         ScopeChainIterator end();
  62
  63         int localDepth();
  64
  65 #ifndef NDEBUG
  66         void print();
  67 #endif
  68
  69         static Structure* createStructure(JSGlobalData& globalData, JSValue proto) { return Structure::create(globalData, proto, TypeInfo(CompoundType, StructureFlags), AnonymousSlotCount, &s_info); }
  70         virtual void visitChildren(SlotVisitor&);
  71         static JS_EXPORTDATA const ClassInfo s_info;
  72
  73     private:
  74         static const unsigned StructureFlags = OverridesVisitChildren;
  75     };
  76
  77     inline ScopeChainNode* ScopeChainNode::push(JSObject* o)
  78     {
  79         ASSERT(o);
  80         return new (globalData) ScopeChainNode(this, o, globalData, globalObject.get(), globalThis.get());
  81     }
  82
  83     inline ScopeChainNode* ScopeChainNode::pop()
  84     {
  85         ASSERT(next);
  86         return next.get();
  87     }
  88
  89     class ScopeChainIterator {
  90     public:
  91         ScopeChainIterator(ScopeChainNode* node)
  92             : m_node(node)
  93         {
  94         }
  95
  96         WriteBarrier<JSObject> const & operator*() const { return m_node->object; }
  97         WriteBarrier<JSObject> const * operator->() const { return &(operator*()); }
  98
  99         ScopeChainIterator& operator++() { m_node = m_node->next.get(); return *this; }
 100
 101         // postfix ++ intentionally omitted
 102
 103         bool operator==(const ScopeChainIterator& other) const { return m_node == other.m_node; }
 104         bool operator!=(const ScopeChainIterator& other) const { return m_node != other.m_node; }
 105
 106     private:
 107         ScopeChainNode* m_node;
 108     };
 109
 110     inline ScopeChainIterator ScopeChainNode::begin()
 111     {
 112         return ScopeChainIterator(this);
 113     }
 114
 115     inline ScopeChainIterator ScopeChainNode::end()
 116     {
 117         return ScopeChainIterator(0);
 118     }
 119
 120     ALWAYS_INLINE JSGlobalData& ExecState::globalData() const
 121     {
 122         ASSERT(scopeChain()->globalData);
 123         return *scopeChain()->globalData;
 124     }
 125
 126     ALWAYS_INLINE JSGlobalObject* ExecState::lexicalGlobalObject() const
 127     {
 128         return scopeChain()->globalObject.get();
 129     }
 130
 131     ALWAYS_INLINE JSObject* ExecState::globalThisValue() const
 132     {
 133         return scopeChain()->globalThis.get();
 134     }
 135
 136     ALWAYS_INLINE ScopeChainNode* Register::scopeChain() const
 137     {
 138         return static_cast<ScopeChainNode*>(jsValue().asCell());
 139     }
 140
 141     ALWAYS_INLINE Register& Register::operator=(ScopeChainNode* scopeChain)
 142     {
 143         *this = JSValue(scopeChain);
 144         return *this;
 145     }
 146
 147 } // namespace JSC
 148
 149 #endif // ScopeChain_h