runtime/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 "JSObject.h"
  33 #include "Register.h"
  34 #include "SymbolTable.h"
  35 #include "UnusedParam.h"
  36 #include <wtf/OwnArrayPtr.h>
  37 #include <wtf/UnusedParam.h>
  38
  39 namespace JSC {
  40
  41     class Register;
  42
  43     class JSVariableObject : public JSObject {
  44         friend class JIT;
  45
  46     public:
  47         SymbolTable& symbolTable() const { return *d->symbolTable; }
  48
  49         virtual void putWithAttributes(ExecState*, const Identifier&, JSValue, unsigned attributes) = 0;
  50
  51         virtual bool deleteProperty(ExecState*, const Identifier&);
  52         virtual void getOwnPropertyNames(ExecState*, PropertyNameArray&, EnumerationMode mode = ExcludeDontEnumProperties);
  53
  54         virtual bool isVariableObject() const;
  55         virtual bool isDynamicScope() const = 0;
  56
  57         Register& registerAt(int index) const { return d->registers[index]; }
  58
  59         static PassRefPtr<Structure> createStructure(JSValue prototype)
  60         {
  61             return Structure::create(prototype, TypeInfo(ObjectType, StructureFlags), AnonymousSlotCount);
  62         }
  63
  64     protected:
  65         static const unsigned StructureFlags = OverridesGetPropertyNames | JSObject::StructureFlags;
  66         // Subclasses of JSVariableObject can subclass this struct to add data
  67         // without increasing their own size (since there's a hard limit on the
  68         // size of a JSCell).
  69         struct JSVariableObjectData {
  70             JSVariableObjectData(SymbolTable* symbolTable, Register* registers)
  71                 : symbolTable(symbolTable)
  72                 , registers(registers)
  73             {
  74                 ASSERT(symbolTable);
  75             }
  76
  77             SymbolTable* symbolTable; // Maps name -> offset from "r" in register file.
  78             Register* registers; // "r" in the register file.
  79             OwnArrayPtr<Register> registerArray; // Independent copy of registers, used when a variable object copies its registers out of the register file.
  80
  81         private:
  82             JSVariableObjectData(const JSVariableObjectData&);
  83             JSVariableObjectData& operator=(const JSVariableObjectData&);
  84         };
  85
  86         JSVariableObject(NonNullPassRefPtr<Structure> structure, JSVariableObjectData* data)
  87             : JSObject(structure)
  88             , d(data) // Subclass owns this pointer.
  89         {
  90         }
  91
  92         Register* copyRegisterArray(Register* src, size_t count);
  93         void setRegisters(Register* r, Register* registerArray);
  94
  95         bool symbolTableGet(const Identifier&, PropertySlot&);
  96         bool symbolTableGet(const Identifier&, PropertyDescriptor&);
  97         bool symbolTableGet(const Identifier&, PropertySlot&, bool& slotIsWriteable);
  98         bool symbolTablePut(const Identifier&, JSValue);
  99         bool symbolTablePutWithAttributes(const Identifier&, JSValue, unsigned attributes);
 100
 101         JSVariableObjectData* d;
 102     };
 103
 104     inline bool JSVariableObject::symbolTableGet(const Identifier& propertyName, PropertySlot& slot)
 105     {
 106         SymbolTableEntry entry = symbolTable().inlineGet(propertyName.ustring().rep());
 107         if (!entry.isNull()) {
 108             slot.setRegisterSlot(&registerAt(entry.getIndex()));
 109             return true;
 110         }
 111         return false;
 112     }
 113
 114     inline bool JSVariableObject::symbolTableGet(const Identifier& propertyName, PropertySlot& slot, bool& slotIsWriteable)
 115     {
 116         SymbolTableEntry entry = symbolTable().inlineGet(propertyName.ustring().rep());
 117         if (!entry.isNull()) {
 118             slot.setRegisterSlot(&registerAt(entry.getIndex()));
 119             slotIsWriteable = !entry.isReadOnly();
 120             return true;
 121         }
 122         return false;
 123     }
 124
 125     inline bool JSVariableObject::symbolTablePut(const Identifier& propertyName, JSValue value)
 126     {
 127         ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
 128
 129         SymbolTableEntry entry = symbolTable().inlineGet(propertyName.ustring().rep());
 130         if (entry.isNull())
 131             return false;
 132         if (entry.isReadOnly())
 133             return true;
 134         registerAt(entry.getIndex()) = value;
 135         return true;
 136     }
 137
 138     inline bool JSVariableObject::symbolTablePutWithAttributes(const Identifier& propertyName, JSValue value, unsigned attributes)
 139     {
 140         ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
 141
 142         SymbolTable::iterator iter = symbolTable().find(propertyName.ustring().rep());
 143         if (iter == symbolTable().end())
 144             return false;
 145         SymbolTableEntry& entry = iter->second;
 146         ASSERT(!entry.isNull());
 147         entry.setAttributes(attributes);
 148         registerAt(entry.getIndex()) = value;
 149         return true;
 150     }
 151
 152     inline Register* JSVariableObject::copyRegisterArray(Register* src, size_t count)
 153     {
 154         Register* registerArray = new Register[count];
 155         memcpy(registerArray, src, count * sizeof(Register));
 156
 157         return registerArray;
 158     }
 159
 160     inline void JSVariableObject::setRegisters(Register* registers, Register* registerArray)
 161     {
 162         ASSERT(registerArray != d->registerArray.get());
 163         d->registerArray.set(registerArray);
 164         d->registers = registers;
 165     }
 166
 167 } // namespace JSC
 168
 169 #endif // JSVariableObject_h