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