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

**

** 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 "qscriptclass.h"

#include "qscriptstring.h"

/*!

  \since 4.4

  \class QScriptClass

  \brief The QScriptClass class provides an interface for defining custom behavior of (a class of) Qt Script objects.

  \ingroup script

  \mainclass

  The QScriptClass class defines an interface for handling various

  aspects of interaction with the Qt Script objects associated with

  the class. Such objects are created by calling

  QScriptEngine::newObject(), passing a pointer to the QScriptClass as

  argument.

  By subclassing QScriptClass, you can define precisely how access to

  properties of the objects that use your class is handled. This

  enables a fully dynamic handling of properties, e.g. it's more

  powerful than QScriptEngine::newQObject(). For example, you can use

  QScriptClass to implement array-type objects (i.e. objects that

  handle the \c{length} property, and properties whose names are valid

  array indexes, in a special way), or to implement a "live"

  (runtime-defined) proxy to an underlying object.

  If you just need to handle access to a set of properties that are

  known at the time an object is created (i.e. "semi-statically"), you

  might consider using QScriptValue::setProperty() to define

  getter/setter functions for the relevant properties, rather than

  subclassing QScriptClass.

  Reimplement queryProperty() to specify which properties are handled

  in a custom way by your script class (i.e. should be

  \bold{delegated} to the QScriptClass), and which properties should

  be handled just like normal Qt Script object properties.

  Reimplement property() and setProperty() to perform the actual

  access (read or write) to the properties that your class

  handles. Additionally, you can reimplement propertyFlags() to

  specify custom flags for your properties.

  Reimplement newIterator() to provide an iterator for objects of your

  custom class. This is only necessary if objects of your class can

  have custom properties that you want to be reported when an object

  is used together with the QScriptValueIterator class, or when an

  object is used in a for-in enumeration statement in a script.

  When implementing custom classes of objects, you typically use

  QScriptValue::setData() to store instance-specific data as part of

  object initialization; the data won't be accessible from scripts

  directly, but you can access it in e.g. your reimplementations of

  property() and setProperty() (by calling QScriptValue::data()) to

  perform custom processing.

  Reimplement prototype() to provide a custom prototype object for

  your script class.

  Reimplement supportsExtension() and extension() if your custom

  script class supports one or more of the extensions specified by the

  Extension enum.

  \sa QScriptClassPropertyIterator, QScriptEngine::newObject(), {Custom Script Class Example}

*/

/*!

    \enum QScriptClass::Extension

    This enum specifies the possible extensions to a QScriptClass.

    \value Callable Instances of this class can be called as functions.

    \value HasInstance Instances of this class implement [[HasInstance]].

    \sa extension()

*/

/*!

    \enum QScriptClass::QueryFlag

    This enum describes flags that are used to query a QScriptClass

    regarding how access to a property should be handled.

    \value HandlesReadAccess The QScriptClass handles read access to this property.

    \value HandlesWriteAccess The QScriptClass handles write access to this property.

    \sa queryProperty()

*/

QT_BEGIN_NAMESPACE

class QScriptClassPrivate

{

    Q_DECLARE_PUBLIC(QScriptClass)

public:

    QScriptClassPrivate() {}

    virtual ~QScriptClassPrivate() {}

    QScriptEngine *engine;

    QScriptClass *q_ptr;

};

/*!

  Constructs a QScriptClass object to be used in the given \a engine.

  The engine does not take ownership of the QScriptClass object.

*/

QScriptClass::QScriptClass(QScriptEngine *engine)

    : d_ptr(new QScriptClassPrivate)

{

    d_ptr->q_ptr = this;

    d_ptr->engine = engine;

}

/*!

  \internal

*/

QScriptClass::QScriptClass(QScriptEngine *engine, QScriptClassPrivate &dd)

    : d_ptr(&dd)

{

    d_ptr->q_ptr = this;

    d_ptr->engine = engine;

}

/*!

  Destroys the QScriptClass object.

  If a QScriptClass object is deleted before the associated engine(),

  any Qt Script objects using the QScriptClass will be "demoted" to

  normal Qt Script objects.

*/

QScriptClass::~QScriptClass()

{

}

/*!

  Returns the engine that this QScriptClass is associated with.

*/

QScriptEngine *QScriptClass::engine() const

{

    Q_D(const QScriptClass);

    return d->engine;

}

/*!

  Returns the object to be used as the prototype of new instances

  of this class (created with QScriptEngine::newObject()).

  The default implementation returns an invalid QScriptValue, meaning

  that the standard Object prototype will be used.  Reimplement this

  function to provide your own custom prototype.

  Typically you initialize your prototype object in the constructor of

  your class, then return it in this function.

  See the "Making Use of Prototype-Based Inheritance" section in the

  QtScript documentation for more information on how prototypes are

  used.

*/

QScriptValue QScriptClass::prototype() const

{

    return QScriptValue();

}

/*!

  Returns the name of the script class.

  Qt Script uses this name to generate a default string representation

  of objects in case you do not provide a toString function.

  The default implementation returns a null string.

*/

QString QScriptClass::name() const

{

    return QString();

}

/*!

  Queries this script class for how access to the property with the

  given \a name of the given \a object should be handled. The given \a

  flags specify the aspects of interest. This function should return a

  subset of \a flags to indicate which aspects of property access

  should be further handled by the script class.

  For example, if the \a flags contain HandlesReadAccess, and you

  would like your class to handle the reading of the property (through

  the property() function), the returned flags should include

  HandlesReadAccess. If the returned flags do not contain

  HandlesReadAccess, the property will be handled as a normal script

  object property.

  You can optionally use the \a id argument to store a value that will

  subsequently be passed on to functions such as property() and

  setProperty().

  The default implementation of this function returns 0.

  Note: This function is only called if the given property isn't

  already a normal property of the object. For example, say you

  advertise that you want to handle read access to property \c{foo},

  but not write access; if \c{foo} is then assigned a value, it will

  become a normal script object property, and subsequently you will no

  longer be queried regarding read access to \c{foo}.

  \sa property()

*/

QScriptClass::QueryFlags QScriptClass::queryProperty(

    const QScriptValue &object, const QScriptString &name,

    QueryFlags flags, uint *id)

{

    Q_UNUSED(object);

    Q_UNUSED(name);

    Q_UNUSED(flags);

    Q_UNUSED(id);

    return 0;

}

/*!

  Returns the value of the property with the given \a name of the given

  \a object.

  The \a id argument is only useful if you assigned a value to it in

  queryProperty().

  The default implementation does nothing and returns an invalid QScriptValue.

  \sa setProperty(), propertyFlags()

*/

QScriptValue QScriptClass::property(const QScriptValue &object,

                                    const QScriptString &name, uint id)

{

    Q_UNUSED(object);

    Q_UNUSED(name);

    Q_UNUSED(id);

    return QScriptValue();

}

/*!

  Returns the flags of the property with the given \a name of the given

  \a object.

  The \a id argument is only useful if you assigned a value to it in

  queryProperty().

  The default implementation returns 0.

  \sa property()

*/

QScriptValue::PropertyFlags QScriptClass::propertyFlags(

    const QScriptValue &object, const QScriptString &name, uint id)

{

    Q_UNUSED(object);

    Q_UNUSED(name);

    Q_UNUSED(id);

    return 0;

}

/*!

  Sets the property with the given \a name of the given \a object to

  the given \a value.

  The \a id argument is only useful if you assigned a value to it in

  queryProperty().

  The default implementation does nothing.

  An invalid \a value represents a request to remove the property.

  \sa property()

*/

void QScriptClass::setProperty(QScriptValue &object, const QScriptString &name,

                               uint id, const QScriptValue &value)

{

    Q_UNUSED(object);

    Q_UNUSED(name);

    Q_UNUSED(id);

    Q_UNUSED(value);

}

/*!

  Returns an iterator for traversing custom properties of the given \a

  object.

  The default implementation returns 0, meaning that there are no

  custom properties to traverse.

  Reimplement this function if objects of your script class can have

  one or more custom properties (e.g. those reported to be handled by

  queryProperty()) that you want to appear when an object's properties

  are enumerated (e.g. by a for-in statement in a script).

  Qt Script takes ownership of the new iterator object.

  \sa QScriptValueIterator

*/

QScriptClassPropertyIterator *QScriptClass::newIterator(const QScriptValue &object)

{

    Q_UNUSED(object);

    return 0;

}

/*!

  Returns true if the QScriptClass supports the given \a extension;

  otherwise, false is returned. By default, no extensions

  are supported.

  Reimplement this function to indicate which extensions your custom

  class supports.

  \sa extension()

*/

bool QScriptClass::supportsExtension(Extension extension) const

{

    Q_UNUSED(extension);

    return false;

}

/*!

  This virtual function can be reimplemented in a QScriptClass

  subclass to provide support for extensions. The optional \a argument

  can be provided as input to the \a extension; the result must be

  returned in the form of a QVariant. You can call supportsExtension()

  to check if an extension is supported by the QScriptClass.  By

  default, no extensions are supported, and this function returns an

  invalid QVariant.

  If you implement the Callable extension, Qt Script will call this

  function when an instance of your class is called as a function

  (e.g. from a script or using QScriptValue::call()).  The \a argument

  will contain a pointer to the QScriptContext that represents the

  function call, and you should return a QVariant that holds the

  result of the function call. In the following example the sum of the

  arguments to the script function are added up and returned:

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

  If you implement the HasInstance extension, Qt Script will call this

  function as part of evaluating the \c{instanceof} operator, as

  described in ECMA-262 Section 11.8.6. The \a argument is a

  QScriptValueList containing two items: The first item is the object

  that HasInstance is being applied to (an instance of your class),

  and the second item can be any value. extension() should return true

  if the value delegates behavior to the object, false otherwise.

  \sa supportsExtension()

*/

QVariant QScriptClass::extension(Extension extension, const QVariant &argument)

{

    Q_UNUSED(extension);

    Q_UNUSED(argument);

    return QVariant();

}

QT_END_NAMESPACE