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

**

** 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 "qscriptstaticscopeobject_p.h"

namespace JSC

{

    ASSERT_CLASS_FITS_IN_CELL(QT_PREPEND_NAMESPACE(QScriptStaticScopeObject));

}

QT_BEGIN_NAMESPACE

/*!

  \class QScriptStaticScopeObject

  \internal

    Represents a static scope object.

    This class allows the VM to determine at JS script compile time whether

    the object has a given property or not. If the object has the property,

    a fast, index-based read/write operation will be used. If the object

    doesn't have the property, the compiler knows it can safely skip this

    object when dynamically resolving the property. Either way, this can

    greatly improve performance.

  \sa QScriptContext::pushScope()

*/

const JSC::ClassInfo QScriptStaticScopeObject::info = { "QScriptStaticScopeObject", 0, 0, 0 };

/*!

    Creates a static scope object with a fixed set of undeletable properties.

    It's not possible to add new properties to the object after construction.

*/

QScriptStaticScopeObject::QScriptStaticScopeObject(WTF::NonNullPassRefPtr<JSC::Structure> structure,

                                                   int propertyCount, const PropertyInfo* props)

    : JSC::JSVariableObject(structure, new Data(/*canGrow=*/false))

{

    int index = growRegisterArray(propertyCount);

    for (int i = 0; i < propertyCount; ++i, --index) {

        const PropertyInfo& prop = props[i];

        JSC::SymbolTableEntry entry(index, prop.attributes);

        symbolTable().add(prop.identifier.ustring().rep(), entry);

        registerAt(index) = prop.value;

    }

}

/*!

    Creates an empty static scope object.

    Properties can be added to the object after construction, either by

    calling QScriptValue::setProperty(), or by pushing the object on the

    scope chain; variable declarations ("var" statements) and function

    declarations in JavaScript will create properties on the scope object.

    Note that once the scope object has been used in a closure and the

    resulting function has been compiled, it's no longer safe to add

    properties to the scope object (because the VM will bypass this

    object the next time the function is executed).

*/

QScriptStaticScopeObject::QScriptStaticScopeObject(WTF::NonNullPassRefPtr<JSC::Structure> structure)

    : JSC::JSVariableObject(structure, new Data(/*canGrow=*/true))

{

}

QScriptStaticScopeObject::~QScriptStaticScopeObject()

{

}

bool QScriptStaticScopeObject::getOwnPropertySlot(JSC::ExecState*, const JSC::Identifier& propertyName, JSC::PropertySlot& slot)

{

    return symbolTableGet(propertyName, slot);

}

bool QScriptStaticScopeObject::getOwnPropertyDescriptor(JSC::ExecState*, const JSC::Identifier& propertyName, JSC::PropertyDescriptor& descriptor)

{

    return symbolTableGet(propertyName, descriptor);

}

void QScriptStaticScopeObject::putWithAttributes(JSC::ExecState* exec, const JSC::Identifier &propertyName, JSC::JSValue value, unsigned attributes)

{

    if (symbolTablePutWithAttributes(propertyName, value, attributes))

        return;

    Q_ASSERT(d_ptr()->canGrow);

    addSymbolTableProperty(propertyName, value, attributes);

}

void QScriptStaticScopeObject::put(JSC::ExecState* exec, const JSC::Identifier& propertyName, JSC::JSValue value, JSC::PutPropertySlot&)

{

    if (symbolTablePut(propertyName, value))

        return;

    Q_ASSERT(d_ptr()->canGrow);

    addSymbolTableProperty(propertyName, value, /*attributes=*/0);

}

bool QScriptStaticScopeObject::deleteProperty(JSC::ExecState*, const JSC::Identifier&)

{

    return false;

}

void QScriptStaticScopeObject::markChildren(JSC::MarkStack& markStack)

{

    JSC::Register* registerArray = d_ptr()->registerArray.get();

    if (!registerArray)

        return;

    markStack.appendValues(reinterpret_cast<JSC::JSValue*>(registerArray), d_ptr()->registerArraySize);

}

void QScriptStaticScopeObject::addSymbolTableProperty(const JSC::Identifier& name, JSC::JSValue value, unsigned attributes)

{

    int index = growRegisterArray(1);

    JSC::SymbolTableEntry newEntry(index, attributes | JSC::DontDelete);

    symbolTable().add(name.ustring().rep(), newEntry);

    registerAt(index) = value;

}

/*!

  Grows the register array by \a count elements, and returns the offset of

  the newly added elements (note that the register file grows downwards,

  starting at index -1).

*/

int QScriptStaticScopeObject::growRegisterArray(int count)

{

    size_t oldSize = d_ptr()->registerArraySize;

    size_t newSize = oldSize + count;

    JSC::Register* registerArray = new JSC::Register[newSize];

    if (d_ptr()->registerArray)

        memcpy(registerArray + count, d_ptr()->registerArray.get(), oldSize * sizeof(JSC::Register));

    setRegisters(registerArray + newSize, registerArray);

    d_ptr()->registerArraySize = newSize;

    return -oldSize - 1;

}

QT_END_NAMESPACE