kjs/JSVariableObject.h

   1 /*
   2  * Copyright (C) 2007, 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  *
   8  * 1.  Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  14  *     its contributors may be used to endorse or promote products derived
  15  *     from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #ifndef JSVariableObject_h
  30 #define JSVariableObject_h
  31
  32 #include "LocalStorage.h"
  33 #include "SymbolTable.h"
  34 #include "object.h"
  35
  36 namespace KJS {
  37
  38     class JSVariableObject : public JSObject {
  39     public:
  40         SymbolTable& symbolTable() { return *d->symbolTable; }
  41         LocalStorage& localStorage() { return d->localStorage; }
  42
  43         void saveLocalStorage(SavedProperties&) const;
  44         void restoreLocalStorage(const SavedProperties&);
  45
  46         virtual bool deleteProperty(ExecState*, const Identifier&);
  47         virtual void getPropertyNames(ExecState*, PropertyNameArray&);
  48
  49         virtual void mark();
  50
  51     protected:
  52         // Subclasses of JSVariableObject can subclass this struct to add data
  53         // without increasing their own size (since there's a hard limit on the
  54         // size of a JSCell).
  55         struct JSVariableObjectData {
  56             JSVariableObjectData() { }
  57             JSVariableObjectData(SymbolTable* s)
  58                 : symbolTable(s) // Subclass owns this pointer.
  59             {
  60             }
  61
  62             LocalStorage localStorage; // Storage for variables in the symbol table.
  63             SymbolTable* symbolTable; // Maps name -> index in localStorage.
  64         };
  65
  66         JSVariableObject() { }
  67
  68         JSVariableObject(JSVariableObjectData* data)
  69             : d(data) // Subclass owns this pointer.
  70         {
  71         }
  72
  73         JSVariableObject(JSValue* proto, JSVariableObjectData* data)
  74             : JSObject(proto)
  75             , d(data) // Subclass owns this pointer.
  76         {
  77         }
  78
  79         bool symbolTableGet(const Identifier&, PropertySlot&);
  80         bool symbolTablePut(const Identifier&, JSValue*, bool checkReadOnly);
  81
  82         JSVariableObjectData* d;
  83     };
  84
  85     inline bool JSVariableObject::symbolTableGet(const Identifier& propertyName, PropertySlot& slot)
  86     {
  87         size_t index = symbolTable().get(propertyName.ustring().rep());
  88         if (index != missingSymbolMarker()) {
  89 #ifndef NDEBUG
  90             // During initialization, the variable object needs to advertise that it has certain
  91             // properties, even if they're not ready for access yet. This check verifies that
  92             // no one tries to access such a property.
  93
  94             // In a release build, we optimize this check away and just return an invalid pointer.
  95             // There's no harm in an invalid pointer, since no one dereferences it.
  96             if (index >= d->localStorage.size()) {
  97                 slot.setUngettable(this);
  98                 return true;
  99             }
 100 #endif
 101             slot.setValueSlot(this, &d->localStorage[index].value);
 102             return true;
 103         }
 104         return false;
 105     }
 106
 107     inline bool JSVariableObject::symbolTablePut(const Identifier& propertyName, JSValue* value, bool checkReadOnly)
 108     {
 109         size_t index = symbolTable().get(propertyName.ustring().rep());
 110         if (index == missingSymbolMarker())
 111             return false;
 112         LocalStorageEntry& entry = d->localStorage[index];
 113         if (checkReadOnly && (entry.attributes & ReadOnly))
 114             return true;
 115         entry.value = value;
 116         return true;
 117     }
 118
 119 } // namespace KJS
 120
 121 #endif // JSVariableObject_h