/****************************************************************************

**

** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtScript module of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL-ONLY$

** GNU Lesser General Public License Usage

** This file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

** $QT_END_LICENSE$

**

****************************************************************************/

#include "config.h"

#include "qscriptcontext.h"

#include "qscriptcontext_p.h"

#include "qscriptcontextinfo.h"

#include "qscriptengine.h"

#include "qscriptengine_p.h"

#include "../bridge/qscriptactivationobject_p.h"

#include "Arguments.h"

#include "CodeBlock.h"

#include "Error.h"

#include "JSFunction.h"

#include "JSObject.h"

#include "JSGlobalObject.h"

#include <QtCore/qstringlist.h>

QT_BEGIN_NAMESPACE

/*!

  \since 4.3

  \class QScriptContext

  \brief The QScriptContext class represents a Qt Script function invocation.

  \ingroup script

  \mainclass

  A QScriptContext provides access to the `this' object and arguments

  passed to a script function. You typically want to access this

  information when you're writing a native (C++) function (see

  QScriptEngine::newFunction()) that will be called from script

  code. For example, when the script code

  \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 0

  is evaluated, a QScriptContext will be created, and the context will

  carry the arguments as QScriptValues; in this particular case, the

  arguments will be one QScriptValue containing the number 20.5, a second

  QScriptValue containing the string \c{"hello"}, and a third QScriptValue

  containing a Qt Script object.

  Use argumentCount() to get the number of arguments passed to the

  function, and argument() to get an argument at a certain index. The

  argumentsObject() function returns a Qt Script array object

  containing all the arguments; you can use the QScriptValueIterator

  to iterate over its elements, or pass the array on as arguments to

  another script function using QScriptValue::call().

  Use thisObject() to get the `this' object associated with the function call,

  and setThisObject() to set the `this' object. If you are implementing a

  native "instance method", you typically fetch the thisObject() and access

  one or more of its properties:

  \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 1

  Use isCalledAsConstructor() to determine if the function was called

  as a constructor (e.g. \c{"new foo()"} (as constructor) or just

  \c{"foo()"}).  When a function is called as a constructor, the

  thisObject() contains the newly constructed object that the function

  is expected to initialize.

  Use throwValue() or throwError() to throw an exception.

  Use callee() to obtain the QScriptValue that represents the function being

  called. This can for example be used to call the function recursively.

  Use parentContext() to get a pointer to the context that precedes

  this context in the activation stack. This is mostly useful for

  debugging purposes (e.g. when constructing some form of backtrace).

  The activationObject() function returns the object that is used to

  hold the local variables associated with this function call. You can

  replace the activation object by calling setActivationObject(). A

  typical usage of these functions is when you want script code to be

  evaluated in the context of the parent context, e.g. to implement an

  include() function:

  \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 2

  Use backtrace() to get a human-readable backtrace associated with

  this context. This can be useful for debugging purposes when

  implementing native functions. The toString() function provides a

  string representation of the context. (QScriptContextInfo provides

  more detailed debugging-related information about the

  QScriptContext.)

  Use engine() to obtain a pointer to the QScriptEngine that this context

  resides in.

  \sa QScriptContextInfo, QScriptEngine::newFunction(), QScriptable

*/

/*!

    \enum QScriptContext::ExecutionState

    This enum specifies the frameution state of the context.

    \value NormalState The context is in a normal state.

    \value ExceptionState The context is in an exceptional state.

*/

/*!

    \enum QScriptContext::Error

    This enum specifies types of error.

    \value ReferenceError A reference error.

    \value SyntaxError A syntax error.

    \value TypeError A type error.

    \value RangeError A range error.

    \value URIError A URI error.

    \value UnknownError An unknown error.

*/

/*!

  \internal

*/

QScriptContext::QScriptContext()

{

    //QScriptContext doesn't exist,  pointer to QScriptContext are just pointer to  JSC::CallFrame

    Q_ASSERT(false);

}

/*!

  Throws an exception with the given \a value.

  Returns the value thrown (the same as the argument).

  \sa throwError(), state()

*/

QScriptValue QScriptContext::throwValue(const QScriptValue &value)

{

    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    JSC::JSValue jscValue = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(value);

    frame->setException(jscValue);

    return value;

}

/*!

  Throws an \a error with the given \a text.

  Returns the created error object.

  The \a text will be stored in the \c{message} property of the error

  object.

  The error object will be initialized to contain information about

  the location where the error occurred; specifically, it will have

  properties \c{lineNumber}, \c{fileName} and \c{stack}. These

  properties are described in \l {QtScript Extensions to ECMAScript}.

  \sa throwValue(), state()

*/

QScriptValue QScriptContext::throwError(Error error, const QString &text)

{

    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    JSC::ErrorType jscError = JSC::GeneralError;

    switch (error) {

    case UnknownError:

        break;

    case ReferenceError:

        jscError = JSC::ReferenceError;

        break;

    case SyntaxError:

        jscError = JSC::SyntaxError;

        break;

    case TypeError:

        jscError = JSC::TypeError;

        break;

    case RangeError:

        jscError = JSC::RangeError;

        break;

    case URIError:

        jscError = JSC::URIError;

        break;

    }

    JSC::JSObject *result = JSC::throwError(frame, jscError, text);

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);

}

/*!

  \overload

  Throws an error with the given \a text.

  Returns the created error object.

  \sa throwValue(), state()

*/

QScriptValue QScriptContext::throwError(const QString &text)

{

    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    JSC::JSObject *result = JSC::throwError(frame, JSC::GeneralError, text);

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);

}

/*!

  Destroys this QScriptContext.

*/

QScriptContext::~QScriptContext()

{

    //QScriptContext doesn't exist,  pointer to QScriptContext are just pointer to JSC::CallFrame

    Q_ASSERT(false);

}

/*!

  Returns the QScriptEngine that this QScriptContext belongs to.

*/

QScriptEngine *QScriptContext::engine() const

{

    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame));

}

/*!

  Returns the function argument at the given \a index.

  If \a index >= argumentCount(), a QScriptValue of

  the primitive type Undefined is returned.

  \sa argumentCount()

*/

QScriptValue QScriptContext::argument(int index) const

{

    if (index < 0)

        return QScriptValue();

    if (index >= argumentCount())

        return QScriptValue(QScriptValue::UndefinedValue);

    QScriptValue v = argumentsObject().property(index);

    return v;

}

/*!

  Returns the callee. The callee is the function object that this

  QScriptContext represents an invocation of.

*/

QScriptValue QScriptContext::callee() const

{

    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(frame->callee());

}

/*!

  Returns the arguments object of this QScriptContext.

  The arguments object has properties \c callee (equal to callee())

  and \c length (equal to argumentCount()), and properties \c 0, \c 1,

  ..., argumentCount() - 1 that provide access to the argument

  values. Initially, property \c P (0 <= \c P < argumentCount()) has

  the same value as argument(\c P). In the case when \c P is less

  than the number of formal parameters of the function, \c P shares

  its value with the corresponding property of the activation object

  (activationObject()). This means that changing this property changes

  the corresponding property of the activation object and vice versa.

  \sa argument(), activationObject()

*/

QScriptValue QScriptContext::argumentsObject() const

{

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

    if (frame == frame->lexicalGlobalObject()->globalExec()) {

        // <global> context doesn't have arguments. return an empty object

        return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame))->newObject();

    }

    //for a js function

    if (frame->codeBlock() && frame->callee()) {

        JSC::JSValue result = frame->interpreter()->retrieveArguments(frame, JSC::asFunction(frame->callee()));

        return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);

    }

    if (frame->callerFrame()->hasHostCallFrameFlag()) {

        // <eval> context doesn't have arguments. return an empty object

        return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame))->newObject();

    }

    //for a native function

    if (!frame->optionalCalleeArguments()) {

        Q_ASSERT(frame->argumentCount() > 0); //we need at least 'this' otherwise we'll crash later

        JSC::Arguments* arguments = new (&frame->globalData())JSC::Arguments(frame, JSC::Arguments::NoParameters);

        frame->setCalleeArguments(arguments);

    }

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(frame->optionalCalleeArguments());

}

/*!

  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.

*/

bool QScriptContext::isCalledAsConstructor() const

{

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

    //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;

}

/*!

  Returns the parent context of this QScriptContext.

*/

QScriptContext *QScriptContext::parentContext() const

{

    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    JSC::CallFrame *callerFrame = frame->callerFrame()->removeHostCallFrameFlag();

    return QScriptEnginePrivate::contextForFrame(callerFrame);

}

/*!

  Returns the number of arguments passed to the function

  in this invocation.

  Note that the argument count can be different from the

  formal number of arguments (the \c{length} property of

  callee()).

  \sa argument()

*/

int QScriptContext::argumentCount() const

{

    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    int argc = frame->argumentCount();

    if (argc != 0)

        --argc; // -1 due to "this"

    return argc;

}

/*!

  \internal

*/

QScriptValue QScriptContext::returnValue() const

{

    qWarning("QScriptContext::returnValue() not implemented");

    return QScriptValue();

}

/*!

  \internal

*/

void QScriptContext::setReturnValue(const QScriptValue &result)

{

    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    JSC::CallFrame *callerFrame = frame->callerFrame();

    if (!callerFrame->codeBlock())

        return;

    Q_ASSERT_X(false, Q_FUNC_INFO, "check me");

    int dst = frame->registers()[JSC::RegisterFile::ReturnValueRegister].i(); // returnValueRegister() is private

    callerFrame[dst] = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(result);

}

/*!

  Returns the activation object of this QScriptContext. The activation

  object provides access to the local variables associated with this

  context.

  \sa argument(), argumentsObject()

*/

QScriptValue QScriptContext::activationObject() const

{

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

    JSC::JSObject *result = 0;

    uint flags = QScriptEnginePrivate::contextFlags(frame);

    if ((flags & QScriptEnginePrivate::NativeContext) && !(flags & QScriptEnginePrivate::HasScopeContext)) {

        //For native functions, lazily create it if needed

        QScript::QScriptActivationObject *scope = new (frame) QScript::QScriptActivationObject(frame);

        frame->setScopeChain(frame->scopeChain()->copy()->push(scope));

        result = scope;

        QScriptEnginePrivate::setContextFlags(frame, flags | QScriptEnginePrivate::HasScopeContext);

    } else {

        // look in scope chain

        JSC::ScopeChainNode *node = frame->scopeChain();

        JSC::ScopeChainIterator it(node);

        for (it = node->begin(); it != node->end(); ++it) {

            if ((*it) && (*it)->isVariableObject()) {

                result = *it;

                break;

            }

        }

    }

    if (!result) {

        if (!parentContext())

            return engine()->globalObject();

        qWarning("QScriptContext::activationObject:  could not get activation object for frame");

        return QScriptValue();

        /*JSC::CodeBlock *codeBlock = frame->codeBlock();

        if (!codeBlock) {

            // non-Qt native function 

            Q_ASSERT(true); //### this should in theorry not happen

            result = new (frame)QScript::QScriptActivationObject(frame);

        } else {

            // ### this is wrong

            JSC::FunctionBodyNode *body = static_cast<JSC::FunctionBodyNode*>(codeBlock->ownerNode());

            result = new (frame)JSC::JSActivation(frame, body);

        }*/

    }

    if (result && result->inherits(&QScript::QScriptActivationObject::info)

        && (static_cast<QScript::QScriptActivationObject*>(result)->delegate() != 0)) {

        // Return the object that property access is being delegated to

        result = static_cast<QScript::QScriptActivationObject*>(result)->delegate();

    }

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);

}

/*!

  Sets the activation object of this QScriptContext to be the given \a

  activation.

  If \a activation is not an object, this function does nothing.

*/

void QScriptContext::setActivationObject(const QScriptValue &activation)

{

    if (!activation.isObject())

        return;

    else if (activation.engine() != engine()) {

        qWarning("QScriptContext::setActivationObject() failed: "

                 "cannot set an object created in "

                 "a different engine");

        return;

    }

    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);

    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);

    JSC::JSObject *object = JSC::asObject(engine->scriptValueToJSCValue(activation));

    if (object == engine->originalGlobalObjectProxy)

        object = engine->originalGlobalObject();

    uint flags = QScriptEnginePrivate::contextFlags(frame);

    if ((flags & QScriptEnginePrivate::NativeContext) && !(flags & QScriptEnginePrivate::HasScopeContext)) {

        //For native functions, we create a scope node

        JSC::JSObject *scope = object;

        if (!scope->isVariableObject()) {

            // Create a QScriptActivationObject that acts as a proxy

            scope = new (frame) QScript::QScriptActivationObject(frame, scope);

        }

        frame->setScopeChain(frame->scopeChain()->copy()->push(scope));

        QScriptEnginePrivate::setContextFlags(frame, flags | QScriptEnginePrivate::HasScopeContext);

        return;

    }

    // else replace the first activation object in the scope chain

    JSC::ScopeChainNode *node = frame->scopeChain();

    while (node != 0) {

        if (node->object && node->object->isVariableObject()) {

            if (!object->isVariableObject()) {

                if (node->object->inherits(&QScript::QScriptActivationObject::info)) {

                    static_cast<QScript::QScriptActivationObject*>(node->object)->setDelegate(object);

                } else {

                    // Create a QScriptActivationObject that acts as a proxy

                    node->object = new (frame) QScript::QScriptActivationObject(frame, object);

                }

            } else {

                node->object = object;

            }

            break;

        }

        node = node->next;

    }

}

/*!

  Returns the `this' object associated with this QScriptContext.

*/

QScriptValue QScriptContext::thisObject() const

{

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

    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);

    JSC::JSValue result = engine->thisForContext(frame);

    if (!result || result.isNull())

        result = frame->globalThisValue();

    return engine->scriptValueFromJSCValue(result);

}