diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1fd95269..a2470ed2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -16,6 +16,7 @@ set (timew_SRCS AtomicFile.cpp AtomicFile.h
                 Extensions.cpp Extensions.h
                 Interval.cpp   Interval.h
                 IntervalFactory.cpp IntervalFactory.h
+                IntervalFilter.cpp IntervalFilter.h
                 Journal.cpp    Journal.h
                 Range.cpp      Range.h
                 Rules.cpp      Rules.h
diff --git a/src/IntervalFilter.cpp b/src/IntervalFilter.cpp
new file mode 100644
index 00000000..5f9f7f01
--- /dev/null
+++ b/src/IntervalFilter.cpp
@@ -0,0 +1,43 @@
+// ///////////////////////////////////////////////////////////////////////////
+//
+//  Copyright , Thomas Lauf, Paul Beckingham, Federico Hernandez.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included
+//  in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+//  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+//  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+//  https://www.opensource.org/licenses/mit-license.php
+//
+// ///////////////////////////////////////////////////////////////////////////
+//
+
+#include <IntervalFilter.h>
+
+bool IntervalFilter::is_done () const
+{
+  return _done;
+}
+
+void IntervalFilter::set_done (bool done)
+{
+  _done = done;
+}
+
+void IntervalFilter::reset ()
+{
+  set_done (false);
+}
diff --git a/src/IntervalFilter.h b/src/IntervalFilter.h
new file mode 100644
index 00000000..ed967832
--- /dev/null
+++ b/src/IntervalFilter.h
@@ -0,0 +1,47 @@
+////////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2021, Thomas Lauf, Paul Beckingham, Federico Hernandez.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+// https://www.opensource.org/licenses/mit-license.php
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef INCLUDED_INTERVALFILTER
+#define INCLUDED_INTERVALFILTER
+
+#include <Interval.h>
+
+class IntervalFilter
+{
+public:
+  virtual bool accepts (const Interval&) = 0;
+  virtual void reset ();
+
+  bool is_done () const;
+
+protected:
+  void set_done (bool);
+
+private:
+  bool _done = false;
+};
+
+#endif //INCLUDED_INTERVALFILTER