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/home/builduser/trunk/pkgs/soprano/BUILD/soprano-2.4.63/soprano/iterator.h

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00001 /*
00002  * This file is part of Soprano Project.
00003  *
00004  * Copyright (C) 2006 Daniele Galdi <daniele.galdi@gmail.com>
00005  * Copyright (C) 2007 Sebastian Trueg <trueg@kde.org>
00006  *
00007  * This library is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Library General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2 of the License, or (at your option) any later version.
00011  *
00012  * This library is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Library General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Library General Public License
00018  * along with this library; see the file COPYING.LIB.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 
00023 #ifndef SOPRANO_ITERATOR_H
00024 #define SOPRANO_ITERATOR_H
00025 
00026 #include <QtCore/QSharedDataPointer>
00027 #include <QtCore/QList>
00028 
00029 #include "iteratorbackend.h"
00030 #include "error.h"
00031 
00032 namespace Soprano {
00033 
00078     template<typename T> class Iterator : public Error::ErrorCache
00079     {
00080     public:
00084         Iterator();
00085 
00090         Iterator( IteratorBackend<T> *sti );
00091 
00092         Iterator( const Iterator &sti );
00093 
00094         virtual ~Iterator();
00095 
00096         Iterator& operator=( const Iterator& );
00097 
00101         void close();
00102 
00108         bool next();
00109 
00116         T current() const;
00117 
00126         T operator*() const;
00127 
00132         bool isValid() const;
00133 
00143         QList<T> allElements();
00144 
00145     protected:
00151         void setBackend( IteratorBackend<T>* b );
00152 
00153         IteratorBackend<T>* backend() const;
00154 
00155     private:
00156         class Private;
00157         QSharedDataPointer<Private> d;
00158     };
00159 }
00160 
00161 
00163 template<typename T> class Soprano::Iterator<T>::Private : public QSharedData
00164 {
00165 public:
00166     Private()
00167         : backend( 0 ) {
00168     }
00169     
00170         ~Private() {
00171             if( backend ) {
00172                 backend->close();
00173                 delete backend;
00174             }
00175         }
00176     
00177         IteratorBackend<T>* backend;
00178 };
00179 
00180 
00181 template<typename T> Soprano::Iterator<T>::Iterator()
00182     : Error::ErrorCache(),
00183       d( new Private() )
00184     
00185 {
00186 }
00187 
00188 template<typename T> Soprano::Iterator<T>::Iterator( IteratorBackend<T> *sti )
00189     : Error::ErrorCache(),
00190       d( new Private() )
00191 {
00192     d->backend = sti;
00193 }
00194 
00195 template<typename T> Soprano::Iterator<T>::Iterator( const Iterator<T> &other )
00196     : Error::ErrorCache(),
00197       d( other.d )
00198 {
00199 }
00200 
00201 template<typename T> Soprano::Iterator<T>::~Iterator()
00202 {
00203 }
00204 
00205 template<typename T> Soprano::Iterator<T>& Soprano::Iterator<T>::operator=( const Iterator<T>& other )
00206 {
00207     d = other.d;
00208     return *this;
00209 }
00210 
00211     template<typename T> void Soprano::Iterator<T>::setBackend( IteratorBackend<T>* b )
00212 {
00213     if ( d->backend != b ) {
00214         // now we want it to detach
00215         d->backend = b;
00216     }
00217 }
00218 
00219 template<typename T> Soprano::IteratorBackend<T>* Soprano::Iterator<T>::backend() const
00220 {
00221     return d->backend;
00222 }
00223 
00224 template<typename T> void Soprano::Iterator<T>::close()
00225 {
00226     // some evil hacking to avoid detachment of the shared data
00227     if( isValid() ) {
00228         const Private* cd = d.constData();
00229         cd->backend->close();
00230         setError( cd->backend->lastError() );
00231     }
00232 }
00233 
00234 template<typename T> bool Soprano::Iterator<T>::next()
00235 {
00236     // some evil hacking to avoid detachment of the shared data
00237     const Private* cd = d.constData();
00238     if( isValid() ) {
00239         bool hasNext = cd->backend->next();
00240         setError( cd->backend->lastError() );
00241         if( !hasNext ) {
00242             cd->backend->close();
00243         }
00244         return hasNext;
00245     }
00246     else {
00247         setError( QString::fromLatin1( "Invalid iterator." ) );
00248         return false;
00249     }
00250 }
00251 
00252 template<typename T> T Soprano::Iterator<T>::current() const
00253 {
00254     if( isValid() ){
00255         T c = d->backend->current();
00256         setError( d->backend->lastError() );
00257         return c;
00258     }
00259     else {
00260         setError( QString::fromLatin1( "Invalid iterator." ) );
00261         return T();
00262     }
00263 }
00264 
00265 template<typename T> T Soprano::Iterator<T>::operator*() const
00266 {
00267     return current();
00268 }
00269 
00270 template<typename T> bool Soprano::Iterator<T>::isValid() const
00271 {
00272     return d->backend != 0;
00273 }
00274 
00275 
00276 template<typename T> QList<T> Soprano::Iterator<T>::allElements()
00277 {
00278     QList<T> sl;
00279     if( isValid() ) {
00280         while ( next() ) {
00281             sl.append( current() );
00282         }
00283         close();
00284     }
00285     return sl;
00286 }
00289 #endif
00290 

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