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/*
* The Type2Type template and the Inheritance Detector are from
* <http://www.cuj.com/experts/1810/alexandr.htm>
* (c) Andrei Alexandrescu <andrei@metalanguage.com> and
* free for any use.
*
* The rest is:
* Copyright (C) 2001 Simon Hausmann <hausmann@kde.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
// -*- mode: c++ -*-
//
// W A R N I N G
// -------------
//
// This file is not part of the KDE API. It exists for the convenience
// of KGenericFactory. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#ifndef KGENERICFACTORY_TCC
#define KGENERICFACTORY_TCC
#include <tqmetaobject.h>
#include <ktypelist.h>
namespace KParts
{
class Part;
}
namespace KDEPrivate
{
template <class Base>
struct InheritanceDetector
{
typedef char ConversionExists;
struct ConversionDoesNotExist { char bleh[ 2 ]; };
static ConversionExists test( Base * );
static ConversionDoesNotExist test( ... );
};
/* Simon: KCC doesn't eat the generic InheritanceDetector<Base>.
Instead we have to use concrete specializations :-(
template <class Base, class Derived>
struct InheritanceTest
{
typedef Derived * DerivedPtr;
enum { Result = sizeof( InheritanceDetector<Base>::test( DerivedPtr() ) ) ==
sizeof( InheritanceDetector<Base>::ConversionExists ) };
};
*/
template <class Derived>
struct TQWidgetInheritanceTest
{
typedef Derived * DerivedPtr;
enum { Result = sizeof( InheritanceDetector<TQWidget>::test( DerivedPtr() ) ) ==
sizeof( InheritanceDetector<TQWidget>::ConversionExists ) };
};
template <class Derived>
struct PartInheritanceTest
{
typedef Derived * DerivedPtr;
enum { Result = sizeof( InheritanceDetector<KParts::Part>::test( DerivedPtr() ) ) ==
sizeof( InheritanceDetector<KParts::Part>::ConversionExists ) };
};
template <bool condition, typename Then, typename Else>
struct If
{
typedef Else Result;
};
template <typename Then, typename Else>
struct If<true, Then, Else>
{
typedef Then Result;
};
// a small helper template, to ease the overloading done in ConcreteFactory
// to choose the right constructor for the given class.
template <class T>
struct Type2Type
{
typedef T OriginalType;
};
// this template is called from the MultiFactory one. It instantiates
// the given class if the className matches. Instantiating is done by
// calling the right constructor (a parentwidget/widgetname/parent/name
// one for Parts, a parentwidget/widgetname one for widgets and last
// but not least the standard default constructor of parent/name .
// the choice of the right constructor is done using an ordered inheritance
// test.
template <class Product, class ParentType = TQObject>
class ConcreteFactory
{
public:
typedef typename If< PartInheritanceTest< Product >::Result,
KParts::Part,
typename If< TQWidgetInheritanceTest< Product >::Result,
TQWidget, TQObject >::Result >::Result BaseType;
static inline Product *create( TQWidget *parentWidget, const char *widgetName,
TQObject *parent, const char *name,
const char *className, const TQStringList &args )
{
TQMetaObject *tqmetaObject = Product::tqstaticMetaObject();
while ( tqmetaObject )
{
if ( !qstrcmp( className, tqmetaObject->className() ) )
return create( parentWidget, widgetName,
parent, name, args, Type2Type<BaseType>() );
tqmetaObject = tqmetaObject->tqsuperClass();
}
return 0;
}
private:
typedef typename If< TQWidgetInheritanceTest<ParentType>::Result,
ParentType, TQWidget >::Result WidgetParentType;
static inline Product *create( TQWidget *parentWidget, const char *widgetName,
TQObject *parent, const char *name,
const TQStringList &args, Type2Type<KParts::Part> )
{
return new Product( parentWidget, widgetName, parent, name, args );
}
static inline Product *create( TQWidget* /*parentWidget*/, const char* /*widgetName*/,
TQObject *parent, const char *name,
const TQStringList &args, Type2Type<TQWidget> )
{
WidgetParentType *p = dynamic_cast<WidgetParentType *>( static_cast<TQT_BASE_OBJECT_NAME*>(parent) );
if ( parent && !p )
return 0;
return new Product( p, name, args );
}
static inline Product *create( TQWidget* /*parentWidget*/, const char* /*widgetName*/,
TQObject *parent, const char *name,
const TQStringList &args, Type2Type<TQObject> )
{
ParentType *p = dynamic_cast<ParentType *>( static_cast<TQT_BASE_OBJECT_NAME*>(parent) );
if ( parent && !p )
return 0;
return new Product( p, name, args );
}
};
// this template is used to iterate through the typelist and call the
// concrete factory for each type. the specializations of this template
// are the ones actually being responsible for iterating, in fact.
template <class Product, class ParentType = TQObject>
class MultiFactory
{
public:
inline static TQObject *create( TQWidget *parentWidget, const char *widgetName,
TQObject *parent, const char *name,
const char *className,
const TQStringList &args )
{
return static_cast<TQObject*>(static_cast<QObject*>(ConcreteFactory<Product, ParentType>::create( parentWidget, widgetName,
parent, name, className,
args )));
}
};
// this specialized template we 'reach' at the end of a typelist
// (the last item in a typelist is the NullType)
template <>
class MultiFactory<KDE::NullType>
{
public:
inline static TQObject *create( TQWidget *, const char *, TQObject *,
const char *, const char *,
const TQStringList & )
{ return 0; }
};
// this specialized template we 'reach' at the end of a typelist
// (the last item in a typelist is the NullType)
template <>
class MultiFactory<KDE::NullType, KDE::NullType>
{
public:
inline static TQObject *create( TQWidget *, const char *, TQObject *,
const char *, const char *,
const TQStringList & )
{ return 0; }
};
template <class Product, class ProductListTail>
class MultiFactory< KTypeList<Product, ProductListTail>, TQObject >
{
public:
inline static TQObject *create( TQWidget *parentWidget, const char *widgetName,
TQObject *parent, const char *name,
const char *className,
const TQStringList &args )
{
// try with the head of the typelist first. the head is always
// a concrete type.
TQObject *object = MultiFactory<Product>::create( parentWidget, widgetName,
parent, name, className,
args );
if ( !object )
object = MultiFactory<ProductListTail>::create( parentWidget, widgetName,
parent, name, className,
args );
return object;
}
};
template <class Product, class ProductListTail,
class ParentType, class ParentTypeListTail>
class MultiFactory< KTypeList<Product, ProductListTail>,
KTypeList<ParentType, ParentTypeListTail> >
{
public:
inline static TQObject *create( TQWidget *parentWidget, const char *widgetName,
TQObject *parent, const char *name,
const char *className,
const TQStringList &args )
{
// try with the head of the typelist first. the head is always
// a concrete type.
TQObject *object = MultiFactory<Product, ParentType>
::create( parentWidget, widgetName,
parent, name, className, args );
// if that failed continue by advancing the typelist, calling this
// template specialization recursively (with T2 being a typelist) .
// at the end we reach the nulltype specialization.
if ( !object )
object = MultiFactory<ProductListTail, ParentTypeListTail>
::create( parentWidget, widgetName,
parent, name, className, args );
return object;
}
};
}
#endif
/*
* vim: et sw=4
*/
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