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+/*
+ Copyright 2009 Ingo Klöcker <kloecker@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.
+*/
+
+#ifndef KCAL_COMPARISONVISITOR_H
+#define KCAL_COMPARISONVISITOR_H
+
+#include "incidencebase.h"
+
+namespace KCal {
+
+/**
+ Helper for type correct comparison of incidences via pointers.
+
+ This class provides a way of correctly comparing one incidence to another,
+ given two IncidenceBase derived pointers. It effectively provides a virtual
+ comparison method which first type checks the two pointers to ensure they
+ reference the same incidence type, before performing the comparison.
+
+ Usage example:
+ @code
+ KCal::Incidence *incidence; // assume this is set somewhere else
+ KCal::Incidence *referenceIncidence; // assume this is set somewhere else
+
+ KCal::ComparisonVisitor visitor;
+
+ // compare
+ if ( visitor.compare( incidence, referenceIncidence ) ) {
+ // incidence and referenceIncidence point to identical incidences
+ }
+ @endcode
+
+ @author Ingo Klöcker <kloecker@kde.org>
+ */
+class ComparisonVisitor : public IncidenceBase::Visitor
+{
+ public:
+ /**
+ Creates a visitor instance.
+ */
+ ComparisonVisitor();
+
+ /**
+ Destroys the instance.
+ */
+ virtual ~ComparisonVisitor();
+
+ /**
+ Compares the incidence referenced by @p incidence to the incidence
+ referenced by @p reference. Returns true, if the incidence referenced
+ by @p incidence is identical to the incidence referenced by @p reference.
+ Also returns true, if @p incidence and @p reference are both @c 0.
+
+ Basically it is a virtual equivalent of
+ @code
+ *incidence == *reference
+ @endcode
+
+ @param incidence pointer to the incidence to compare with the reference incidence
+ @param reference pointer to the reference incidence
+
+ @return @c true if the two incidences are identical or both @c 0
+ */
+ bool compare( IncidenceBase *incidence, const IncidenceBase *reference );
+
+ /**
+ Compares the event referenced by @p event to the incidence passed to
+ compare().
+
+ @return @c true if the event is identical to the reference incidence
+ */
+ virtual bool visit( Event *event );
+
+ /**
+ Compares the todo referenced by @p todo to the incidence passed to
+ compare().
+
+ @return @c true if the todo is identical to the reference incidence
+ */
+ virtual bool visit( Todo *todo );
+
+ /**
+ Compares the journal referenced by @p journal to the incidence passed to
+ compare().
+
+ @return @c true if the journal is identical to the reference incidence
+ */
+ virtual bool visit( Journal *journal );
+
+ /**
+ Compares the freebusy object referenced by @p freebusy to the incidence passed to
+ compare().
+
+ @return @c true if the freebusy object is identical to the reference incidence
+ */
+ virtual bool visit( FreeBusy *freebusy );
+
+ private:
+ //@cond PRIVATE
+ class Private;
+ Private *const d;
+ //@endcond
+};
+
+}
+
+#endif // KCAL_COMPARISONVISITOR_H