src/script/api/qscriptclass.cpp
changeset 0 1918ee327afb
child 3 41300fa6a67c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/script/api/qscriptclass.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,397 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 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.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** 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