1 files changed, 122 insertions, 0 deletions
diff --git a/libkcal/comparisonvisitor.h b/libkcal/comparisonvisitor.h
new file mode 100644
index 000000000..0712f9c04
--- /dev/null
+++ b/libkcal/comparisonvisitor.h
@@ -0,0 +1,122 @@
+/*
+  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