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      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
    170