/*
 * Copyright (C) 2007, 2008, 2012 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer. 
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution. 
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef JSEnvironmentRecord_h
#define JSEnvironmentRecord_h

#include "JSObject.h"
#include "JSSymbolTableObject.h"
#include "Register.h"
#include "SymbolTable.h"
#include <wtf/UnusedParam.h>
#include <wtf/OwnArrayPtr.h>

namespace JSC {

    class LLIntOffsetsExtractor;
    class Register;

    class JSEnvironmentRecord : public JSSymbolTableObject {
        friend class JIT;
        friend class LLIntOffsetsExtractor;

    public:
        typedef JSSymbolTableObject Base;

        WriteBarrierBase<Unknown>* variables()
        {
            return bitwise_cast<WriteBarrierBase<Unknown>*>(bitwise_cast<char*>(this) + offsetOfVariables());
        }

        bool isValidScopeOffset(ScopeOffset offset)
        {
            return !!offset && offset.offset() < symbolTable()->scopeSize();
        }

        WriteBarrierBase<Unknown>& variableAt(ScopeOffset offset)
        {
            ASSERT(isValidScopeOffset(offset));
            return variables()[offset.offset()];
        }

        static size_t offsetOfVariables()
        {
            return WTF::roundUpToMultipleOf<sizeof(WriteBarrier<Unknown>)>(sizeof(JSEnvironmentRecord));
        }

        static ptrdiff_t offsetOfVariable(ScopeOffset offset)
        {
            return offsetOfVariables() + offset.offset() * sizeof(WriteBarrier<Unknown>);
        }

        DECLARE_INFO;

        static size_t allocationSizeForScopeSize(unsigned scopeSize)
        {
            return offsetOfVariables() + scopeSize * sizeof(WriteBarrier<Unknown>);
        }

        static size_t allocationSize(SymbolTable* symbolTable)
        {
            return allocationSizeForScopeSize(symbolTable->scopeSize());
        }

    protected:
        static const unsigned StructureFlags = Base::StructureFlags;

        JSEnvironmentRecord(
			JSGlobalData& globalData,
			Structure* structure,
            JSScope* scope,
            SymbolTable* symbolTable
        )
        : Base(globalData, structure, scope, symbolTable)
        {
        }

        void finishCreationUninitialized(VM& vm)
        {
            Base::finishCreation(vm);
        }

        void finishCreation(VM& vm, JSValue value)
        {
            finishCreationUninitialized(vm);
            ASSERT(value == jsUndefined() || value == jsTDZValue());
            for (unsigned i = symbolTable()->scopeSize(); i--;) {
                // Filling this with undefined/TDZEmptyValue is useful because that's what variables start out as.
                variableAt(ScopeOffset(i)).setStartingValue(value);
            }
        }

        static void visitChildren(JSCell*, SlotVisitor&);
    };

} // namespace JSC

#endif // JSEnvironmentRecord_h
