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 LLIntOffsetsExtractor;
  34     class ScopeChainIterator;
  35     class SlotVisitor;
  36
  37     class ScopeChainNode : public JSCell {
  38     private:
  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         }
  48
  49     protected:
  50         void finishCreation(JSGlobalData* globalData, JSGlobalObject* globalObject)
  51         {
  52             Base::finishCreation(*globalData);
  53             ASSERT_UNUSED(globalObject, globalObject);
  54         }
  55
  56     public:
  57         typedef JSCell Base;
  58
  59         static ScopeChainNode* create(ExecState* exec, ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis)
  60         {
  61             ScopeChainNode* node = new (NotNull, allocateCell<ScopeChainNode>(*exec->heap())) ScopeChainNode(next, object, globalData, globalObject, globalThis);
  62             node->finishCreation(globalData, globalObject);
  63             return node;
  64         }
  65         static ScopeChainNode* create(ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis)
  66         {
  67             ScopeChainNode* node = new (NotNull, allocateCell<ScopeChainNode>(globalData->heap)) ScopeChainNode(next, object, globalData, globalObject, globalThis);
  68             node->finishCreation(globalData, globalObject);
  69             return node;
  70         }
  71
  72         JSGlobalData* globalData;
  73         WriteBarrier<ScopeChainNode> next;
  74         WriteBarrier<JSObject> object;
  75         WriteBarrier<JSGlobalObject> globalObject;
  76         WriteBarrier<JSObject> globalThis;
  77
  78         ScopeChainNode* push(JSObject*);
  79         ScopeChainNode* pop();
  80
  81         ScopeChainIterator begin();
  82         ScopeChainIterator end();
  83
  84         int localDepth();
  85
  86 #ifndef NDEBUG
  87         void print();
  88 #endif
  89
  90         static Structure* createStructure(JSGlobalData& globalData, JSGlobalObject* globalObject, JSValue proto) { return Structure::create(globalData, globalObject, proto, TypeInfo(CompoundType, StructureFlags), &s_info); }
  91         static void visitChildren(JSCell*, SlotVisitor&);
  92         static JS_EXPORTDATA const ClassInfo s_info;
  93
  94     private:
  95         friend class LLIntOffsetsExtractor;
  96
  97         static const unsigned StructureFlags = OverridesVisitChildren;
  98     };
  99
 100     inline ScopeChainNode* ScopeChainNode::push(JSObject* o)
 101     {
 102         ASSERT(o);
 103         return ScopeChainNode::create(this, o, globalData, globalObject.get(), globalThis.get());
 104     }
 105
 106     inline ScopeChainNode* ScopeChainNode::pop()
 107     {
 108         ASSERT(next);
 109         return next.get();
 110     }
 111
 112     class ScopeChainIterator {
 113     public:
 114         ScopeChainIterator(ScopeChainNode* node)
 115             : m_node(node)
 116         {
 117         }
 118
 119         WriteBarrier<JSObject> const & operator*() const { return m_node->object; }
 120         WriteBarrier<JSObject> const * operator->() const { return &(operator*()); }
 121
 122         ScopeChainIterator& operator++() { m_node = m_node->next.get(); return *this; }
 123
 124         // postfix ++ intentionally omitted
 125
 126         bool operator==(const ScopeChainIterator& other) const { return m_node == other.m_node; }
 127         bool operator!=(const ScopeChainIterator& other) const { return m_node != other.m_node; }
 128
 129     private:
 130         ScopeChainNode* m_node;
 131     };
 132
 133     inline ScopeChainIterator ScopeChainNode::begin()
 134     {
 135         return ScopeChainIterator(this);
 136     }
 137
 138     inline ScopeChainIterator ScopeChainNode::end()
 139     {
 140         return ScopeChainIterator(0);
 141     }
 142
 143     ALWAYS_INLINE JSGlobalData& ExecState::globalData() const
 144     {
 145         ASSERT(scopeChain()->globalData);
 146         return *scopeChain()->globalData;
 147     }
 148
 149     ALWAYS_INLINE JSGlobalObject* ExecState::lexicalGlobalObject() const
 150     {
 151         return scopeChain()->globalObject.get();
 152     }
 153
 154     ALWAYS_INLINE JSObject* ExecState::globalThisValue() const
 155     {
 156         return scopeChain()->globalThis.get();
 157     }
 158
 159     ALWAYS_INLINE ScopeChainNode* Register::scopeChain() const
 160     {
 161         return static_cast<ScopeChainNode*>(jsValue().asCell());
 162     }
 163
 164     ALWAYS_INLINE Register& Register::operator=(ScopeChainNode* scopeChain)
 165     {
 166         *this = JSValue(scopeChain);
 167         return *this;
 168     }
 169
 170 } // namespace JSC
 171
 172 #endif // ScopeChain_h