/*!
  Returns true if the function was called as a constructor
  (e.g. \c{"new foo()"}); otherwise returns false.

  When a function is called as constructor, the thisObject()
  contains the newly constructed object to be initialized.

  \note This function is only guaranteed to work for a context
  corresponding to native functions.
*/
bool QScriptContext::isCalledAsConstructor() const
{
    JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this));
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));

    //For native functions, look up flags.
    uint flags = QScriptEnginePrivate::contextFlags(frame);
    if (flags & QScriptEnginePrivate::NativeContext)
        return flags & QScriptEnginePrivate::CalledAsConstructorContext;

    //Not a native function, try to look up in the bytecode if we where called from op_construct
    JSC::Instruction* returnPC = frame->returnPC();

    if (!returnPC)
        return false;

    JSC::CallFrame *callerFrame = QScriptEnginePrivate::frameForContext(parentContext());
    if (!callerFrame)
        return false;

    if (returnPC[-JSC::op_construct_length].u.opcode == frame->interpreter()->getOpcode(JSC::op_construct)) {
        //We are maybe called from the op_construct opcode which has 6 opperands.
        //But we need to check we are not called from op_call with 4 opperands

        //we make sure that the returnPC[-1] (thisRegister) is smaller than the returnPC[-3] (registerOffset)
        //as if it was an op_call, the returnPC[-1] would be the registerOffset, bigger than returnPC[-3] (funcRegister)
        return returnPC[-1].u.operand < returnPC[-3].u.operand;
    }
    return false;
}
/*!
  \internal
*/
QScriptContextInfoPrivate::QScriptContextInfoPrivate(const QScriptContext *context)
{
    Q_ASSERT(context);
    functionType = QScriptContextInfo::NativeFunction;
    functionMetaIndex = -1;
    functionStartLineNumber = -1;
    functionEndLineNumber = -1;
    scriptId = -1;
    lineNumber = -1;
    columnNumber = -1;

    JSC::CallFrame *frame = const_cast<JSC::CallFrame *>(QScriptEnginePrivate::frameForContext(context));

    // Get the line number:

    //We need to know the context directly up in the backtrace, in order to get the line number, and adjust the global context
    JSC::CallFrame *rewindContext = QScriptEnginePrivate::get(context->engine())->currentFrame;
    if (QScriptEnginePrivate::contextForFrame(rewindContext) == context) {  //top context
        frame = rewindContext; //for retreiving the global context's "fake" frame
        // An agent might have provided the line number.
        lineNumber = QScript::scriptEngineFromExec(frame)->agentLineNumber;
        if (lineNumber == -1)
            lineNumber = QScript::scriptEngineFromExec(frame)->uncaughtExceptionLineNumber;
    } else {
        // rewind the stack from the top in order to find the frame from the caller where the returnPC is stored
        while (rewindContext && QScriptEnginePrivate::contextForFrame(rewindContext->callerFrame()->removeHostCallFrameFlag()) != context)
            rewindContext = rewindContext->callerFrame()->removeHostCallFrameFlag();
        if (rewindContext) {
            frame = rewindContext->callerFrame()->removeHostCallFrameFlag(); //for retreiving the global context's "fake" frame

            JSC::Instruction *returnPC = rewindContext->returnPC();
            JSC::CodeBlock *codeBlock = frame->codeBlock();
            if (returnPC && codeBlock && QScriptEnginePrivate::hasValidCodeBlockRegister(frame)) {
#if ENABLE(JIT)
                JSC::JITCode code = codeBlock->getJITCode();
                uintptr_t jitOffset = reinterpret_cast<uintptr_t>(JSC::ReturnAddressPtr(returnPC).value()) - reinterpret_cast<uintptr_t>(code.addressForCall().executableAddress());
                // We can only use the JIT code offset if it's smaller than the JIT size;
                // otherwise calling getBytecodeIndex() is meaningless.
                if (jitOffset < code.size()) {
                    unsigned bytecodeOffset = codeBlock->getBytecodeIndex(frame, JSC::ReturnAddressPtr(returnPC));
#else
                unsigned bytecodeOffset = returnPC - codeBlock->instructions().begin();
#endif
                bytecodeOffset--; //because returnPC is on the next instruction. We want the current one
                lineNumber = codeBlock->lineNumberForBytecodeOffset(const_cast<JSC::ExecState *>(frame), bytecodeOffset);
#if ENABLE(JIT)
                }
#endif
            }
        }
    }

    // Get the filename and the scriptId:
    JSC::CodeBlock *codeBlock = frame->codeBlock();
    if (codeBlock && QScriptEnginePrivate::hasValidCodeBlockRegister(frame)) {
           JSC::SourceProvider *source = codeBlock->source();
           scriptId = source->asID();
           fileName = source->url();
    }

    // Get the others information:
    JSC::JSObject *callee = frame->callee();
    if (callee && callee->inherits(&JSC::InternalFunction::info))
        functionName = JSC::asInternalFunction(callee)->name(frame);
    if (callee && callee->inherits(&JSC::JSFunction::info)
        && !JSC::asFunction(callee)->isHostFunction()) {
        functionType = QScriptContextInfo::ScriptFunction;
        JSC::FunctionExecutable *body = JSC::asFunction(callee)->jsExecutable();
        functionStartLineNumber = body->lineNo();
        functionEndLineNumber = body->lastLine();
        for (size_t i = 0; i < body->parameterCount(); ++i)
            parameterNames.append(body->parameterName(i));
        // ### get the function name from the AST
    } else if (callee && callee->inherits(&QScript::QtFunction::info)) {
        functionType = QScriptContextInfo::QtFunction;
        functionMetaIndex = static_cast<QScript::QtFunction*>(callee)->specificIndex(context);
        const QMetaObject *meta = static_cast<QScript::QtFunction*>(callee)->metaObject();
        if (meta != 0) {
            QMetaMethod method = meta->method(functionMetaIndex);
            QList<QByteArray> formals = method.parameterNames();
            for (int i = 0; i < formals.count(); ++i)
                parameterNames.append(QLatin1String(formals.at(i)));
        }
    }
    else if (callee && callee->inherits(&QScript::QtPropertyFunction::info)) {
        functionType = QScriptContextInfo::QtPropertyFunction;
        functionMetaIndex = static_cast<QScript::QtPropertyFunction*>(callee)->propertyIndex();
    }
}