qscriptcontext.cpp

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/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** 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
** us via http://www.qt-project.org/.
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** $QT_END_LICENSE$
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****************************************************************************/

#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

QScriptContext::QScriptContext()
{
    //QScriptContext doesn't exist,  pointer to QScriptContext are just pointer to  JSC::CallFrame
    Q_ASSERT(false);
}

QScriptValue QScriptContext::throwValue(const QScriptValue &value)
{
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    JSC::JSValue jscValue = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(value);
    frame->setException(jscValue);
    return value;
}

QScriptValue QScriptContext::throwError(Error error, const QString &text)
{
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    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);
}

QScriptValue QScriptContext::throwError(const QString &text)
{
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    JSC::JSObject *result = JSC::throwError(frame, JSC::GeneralError, text);
    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);
}

QScriptContext::~QScriptContext()
{
    //QScriptContext doesn't exist,  pointer to QScriptContext are just pointer to JSC::CallFrame
    Q_ASSERT(false);
}

QScriptEngine *QScriptContext::engine() const
{
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame));
}

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;
}

QScriptValue QScriptContext::callee() const
{
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScriptEnginePrivate *eng = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(eng);
    if (frame->callee() == eng->originalGlobalObject()) {
        // This is a pushContext()-created context; the callee is a lie.
        Q_ASSERT(QScriptEnginePrivate::contextFlags(const_cast<JSC::CallFrame*>(frame)) & QScriptEnginePrivate::NativeContext);
        return QScriptValue();
    }
    return eng->scriptValueFromJSCValue(frame->callee());
}

QScriptValue QScriptContext::argumentsObject() const
{
    JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this));
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));

    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()) {
        if (!QScriptEnginePrivate::hasValidCodeBlockRegister(frame)) {
            // We have a built-in JS host call.
            // codeBlock is needed by retrieveArguments(), but since it
            // contains junk, we would crash. Return an invalid value for now.
            return QScriptValue();
        }
        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()
        && QScriptEnginePrivate::hasValidCodeBlockRegister(frame)) { // Make sure we don't go here for host JSFunctions
        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());
}

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;
}

QScriptContext *QScriptContext::parentContext() const
{
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    JSC::CallFrame *callerFrame = frame->callerFrame()->removeHostCallFrameFlag();
    return QScriptEnginePrivate::contextForFrame(callerFrame);
}

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;
}

QScriptValue QScriptContext::returnValue() const
{
    qWarning("QScriptContext::returnValue() not implemented");
    return QScriptValue();
}

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);
}

QScriptValue QScriptContext::activationObject() const
{
    JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this));
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    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);
}

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);
    QScript::APIShim shim(engine);
    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;
    }
}

QScriptValue QScriptContext::thisObject() const
{
    JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this));
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    JSC::JSValue result = engine->thisForContext(frame);
    if (!result || result.isNull())
        result = frame->globalThisValue();
    return engine->scriptValueFromJSCValue(result);
}

void QScriptContext::setThisObject(const QScriptValue &thisObject)
{
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    if (!thisObject.isObject())
        return;
    if (thisObject.engine() != engine()) {
        qWarning("QScriptContext::setThisObject() failed: "
                 "cannot set an object created in "
                 "a different engine");
        return;
    }
    if (frame == frame->lexicalGlobalObject()->globalExec()) {
        engine()->setGlobalObject(thisObject);
        return;
    }
    JSC::JSValue jscThisObject = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(thisObject);
    JSC::CodeBlock *cb = frame->codeBlock();
    if (cb != 0) {
        frame[cb->thisRegister()] = jscThisObject;
    } else {
        JSC::Register* thisRegister = QScriptEnginePrivate::thisRegisterForFrame(frame);
        thisRegister[0] = jscThisObject;
    }
}

QScriptContext::ExecutionState QScriptContext::state() const
{
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    if (frame->hadException())
        return QScriptContext::ExceptionState;
    return QScriptContext::NormalState;
}

QStringList QScriptContext::backtrace() const
{
    QStringList result;
    const QScriptContext *ctx = this;
    while (ctx) {
        result.append(ctx->toString());
        ctx = ctx->parentContext();
    }
    return result;
}

QString QScriptContext::toString() const
{
    QScriptContextInfo info(this);
    QString result;

    QString functionName = info.functionName();
    if (functionName.isEmpty()) {
        if (parentContext()) {
            const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
            if (info.functionType() == QScriptContextInfo::ScriptFunction)
                result.append(QLatin1String("<anonymous>"));
            else if(frame->callerFrame()->hasHostCallFrameFlag())
                result.append(QLatin1String("<eval>"));
            else
                result.append(QLatin1String("<native>"));
        } else {
            result.append(QLatin1String("<global>"));
        }
    } else {
        result.append(functionName);
    }

    QStringList parameterNames = info.functionParameterNames();
    result.append(QLatin1Char('('));
    for (int i = 0; i < argumentCount(); ++i) {
        if (i > 0)
            result.append(QLatin1String(", "));
        if (i < parameterNames.count()) {
            result.append(parameterNames.at(i));
            result.append(QLatin1String(" = "));
        }
        QScriptValue arg = argument(i);
        if (arg.isString())
            result.append(QLatin1Char('\''));
        result.append(arg.toString());
        if (arg.isString())
            result.append(QLatin1Char('\''));

    }
    result.append(QLatin1Char(')'));

    QString fileName = info.fileName();
    int lineNumber = info.lineNumber();
    result.append(QLatin1String(" at "));
    if (!fileName.isEmpty()) {
        result.append(fileName);
        result.append(QLatin1Char(':'));
    }
    result.append(QString::number(lineNumber));
    return result;
}

QScriptValueList QScriptContext::scopeChain() const
{
    activationObject(); //ensure the creation of the normal scope for native context
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    QScriptValueList result;
    JSC::ScopeChainNode *node = frame->scopeChain();
    JSC::ScopeChainIterator it(node);
    for (it = node->begin(); it != node->end(); ++it) {
        JSC::JSObject *object = *it;
        if (!object)
            continue;
        if (object->inherits(&QScript::QScriptActivationObject::info)
            && (static_cast<QScript::QScriptActivationObject*>(object)->delegate() != 0)) {
            // Return the object that property access is being delegated to
            object = static_cast<QScript::QScriptActivationObject*>(object)->delegate();
        }
        result.append(engine->scriptValueFromJSCValue(object));
    }
    return result;
}

void QScriptContext::pushScope(const QScriptValue &object)
{
    activationObject(); //ensure the creation of the normal scope for native context
    if (!object.isObject())
        return;
    else if (object.engine() != engine()) {
        qWarning("QScriptContext::pushScope() failed: "
                 "cannot push an object created in "
                 "a different engine");
        return;
    }
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    JSC::JSObject *jscObject = JSC::asObject(engine->scriptValueToJSCValue(object));
    if (jscObject == engine->originalGlobalObjectProxy)
        jscObject = engine->originalGlobalObject();
    JSC::ScopeChainNode *scope = frame->scopeChain();
    Q_ASSERT(scope != 0);
    if (!scope->object) {
        // pushing to an "empty" chain
        if (!jscObject->isGlobalObject()) {
            qWarning("QScriptContext::pushScope() failed: initial object in scope chain has to be the Global Object");
            return;
        }
        scope->object = jscObject;
    }
    else
        frame->setScopeChain(scope->push(jscObject));
}

QScriptValue QScriptContext::popScope()
{
    activationObject(); //ensure the creation of the normal scope for native context
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    JSC::ScopeChainNode *scope = frame->scopeChain();
    Q_ASSERT(scope != 0);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    QScriptValue result = engine->scriptValueFromJSCValue(scope->object);
    if (!scope->next) {
        // We cannot have a null scope chain, so just zap the object pointer.
        scope->object = 0;
    } else {
        frame->setScopeChain(scope->pop());
    }
    return result;
}

QT_END_NAMESPACE