/*

 *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)

 *  Copyright (C) 2001 Peter Kelly (pmk@post.com)

 *  Copyright (C) 2003, 2007, 2008 Apple Inc. All rights reserved.

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Library General Public

 *  License as published by the Free Software Foundation; either

 *  version 2 of the License, or (at your option) any later version.

 *

 *  This library is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 *  Library General Public License for more details.

 *

 *  You should have received a copy of the GNU Library General Public License

 *  along with this library; see the file COPYING.LIB.  If not, write to

 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 *  Boston, MA 02110-1301, USA.

 *

 */

#ifndef CallFrame_h

#define CallFrame_h

#include "JSGlobalData.h"

#include "MacroAssemblerCodeRef.h"

#include "RegisterFile.h"

#include "ScopeChain.h"

namespace JSC  {

    class Arguments;

    class JSActivation;

    class Interpreter;

    // Represents the current state of script execution.

    // Passed as the first argument to most functions.

    class ExecState : private Register {

    public:

        JSObject* callee() const { return this[RegisterFile::Callee].function(); }

        CodeBlock* codeBlock() const { return this[RegisterFile::CodeBlock].Register::codeBlock(); }

        ScopeChainNode* scopeChain() const

        {

            ASSERT(this[RegisterFile::ScopeChain].Register::scopeChain());

            return this[RegisterFile::ScopeChain].Register::scopeChain();

        }

        // Global object in which execution began.

        JSGlobalObject* dynamicGlobalObject();

        // Global object in which the currently executing code was defined.

        // Differs from dynamicGlobalObject() during function calls across web browser frames.

        JSGlobalObject* lexicalGlobalObject() const

        {

            return scopeChain()->globalObject;

        }

        // Differs from lexicalGlobalObject because this will have DOM window shell rather than

        // the actual DOM window, which can't be "this" for security reasons.

        JSObject* globalThisValue() const

        {

            return scopeChain()->globalThis;

        }

        // FIXME: Elsewhere, we use JSGlobalData* rather than JSGlobalData&.

        // We should make this more uniform and either use a reference everywhere

        // or a pointer everywhere.

        JSGlobalData& globalData() const

        {

            ASSERT(scopeChain()->globalData);

            return *scopeChain()->globalData;

        }

        // Convenience functions for access to global data.

        // It takes a few memory references to get from a call frame to the global data

        // pointer, so these are inefficient, and should be used sparingly in new code.

        // But they're used in many places in legacy code, so they're not going away any time soon.

        void clearException() { globalData().exception = JSValue(); }

        JSValue exception() const { return globalData().exception; }

        JSValue* exceptionSlot() { return &globalData().exception; }

        bool hadException() const { return globalData().exception; }

        const CommonIdentifiers& propertyNames() const { return *globalData().propertyNames; }

        const MarkedArgumentBuffer& emptyList() const { return *globalData().emptyList; }

        Interpreter* interpreter() { return globalData().interpreter; }

        Heap* heap() { return &globalData().heap; }

#ifndef NDEBUG

        void dumpCaller();

#endif

        static const HashTable* arrayTable(CallFrame* callFrame) { return callFrame->globalData().arrayTable; }

        static const HashTable* dateTable(CallFrame* callFrame) { return callFrame->globalData().dateTable; }

        static const HashTable* jsonTable(CallFrame* callFrame) { return callFrame->globalData().jsonTable; }

        static const HashTable* mathTable(CallFrame* callFrame) { return callFrame->globalData().mathTable; }

        static const HashTable* numberTable(CallFrame* callFrame) { return callFrame->globalData().numberTable; }

        static const HashTable* regExpTable(CallFrame* callFrame) { return callFrame->globalData().regExpTable; }

        static const HashTable* regExpConstructorTable(CallFrame* callFrame) { return callFrame->globalData().regExpConstructorTable; }

        static const HashTable* stringTable(CallFrame* callFrame) { return callFrame->globalData().stringTable; }

        static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }

        Register* registers() { return this; }

        CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }

        CallFrame* callerFrame() const { return this[RegisterFile::CallerFrame].callFrame(); }

#if ENABLE(JIT)

        ReturnAddressPtr returnPC() const { return ReturnAddressPtr(this[RegisterFile::ReturnPC].vPC()); }

#endif

#if ENABLE(INTERPRETER)

        Instruction* returnVPC() const { return this[RegisterFile::ReturnPC].vPC(); }

#endif

        void setCallerFrame(CallFrame* callerFrame) { static_cast<Register*>(this)[RegisterFile::CallerFrame] = callerFrame; }

        void setScopeChain(ScopeChainNode* scopeChain) { static_cast<Register*>(this)[RegisterFile::ScopeChain] = scopeChain; }

        ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, ScopeChainNode* scopeChain,

            CallFrame* callerFrame, int argc, JSObject* callee)

        {

            ASSERT(callerFrame); // Use noCaller() rather than 0 for the outer host call frame caller.

            ASSERT(callerFrame == noCaller() || callerFrame->removeHostCallFrameFlag()->registerFile()->end() >= this);

            setCodeBlock(codeBlock);

            setScopeChain(scopeChain);

            setCallerFrame(callerFrame);

            setReturnPC(vPC); // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.

            setArgumentCountIncludingThis(argc); // original argument count (for the sake of the "arguments" object)

            setCallee(callee);

        }

        // Read a register from the codeframe (or constant from the CodeBlock).

        inline Register& r(int);

        // Access to arguments.

        int hostThisRegister() { return -RegisterFile::CallFrameHeaderSize - argumentCountIncludingThis(); }

        JSValue hostThisValue() { return this[hostThisRegister()].jsValue(); }

        size_t argumentCount() const { return argumentCountIncludingThis() - 1; }

        size_t argumentCountIncludingThis() const { return this[RegisterFile::ArgumentCount].i(); }

        JSValue argument(int argumentNumber)

        {

            int argumentIndex = -RegisterFile::CallFrameHeaderSize - this[RegisterFile::ArgumentCount].i() + argumentNumber + 1;

            if (argumentIndex >= -RegisterFile::CallFrameHeaderSize)

                return jsUndefined();

            return this[argumentIndex].jsValue();

        }

        static CallFrame* noCaller() { return reinterpret_cast<CallFrame*>(HostCallFrameFlag); }

        bool hasHostCallFrameFlag() const { return reinterpret_cast<intptr_t>(this) & HostCallFrameFlag; }

        CallFrame* addHostCallFrameFlag() const { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) | HostCallFrameFlag); }

        CallFrame* removeHostCallFrameFlag() { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) & ~HostCallFrameFlag); }

        void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[RegisterFile::ArgumentCount] = Register::withInt(count); }

        void setCallee(JSObject* callee) { static_cast<Register*>(this)[RegisterFile::Callee] = Register::withCallee(callee); }

        void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[RegisterFile::CodeBlock] = codeBlock; }

        void setReturnPC(void* value) { static_cast<Register*>(this)[RegisterFile::ReturnPC] = (Instruction*)value; }

    private:

        static const intptr_t HostCallFrameFlag = 1;

#ifndef NDEBUG

        RegisterFile* registerFile();

#endif

        ExecState();

        ~ExecState();

    };

} // namespace JSC

#endif // CallFrame_h