diff --git a/src/source.h b/src/source.h
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+++ b/src/source.h
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+/*
+  Copyright © 2018 Hasan Yavuz Özderya
+
+  This file is part of serialplot.
+
+  serialplot is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  serialplot 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with serialplot.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SOURCE_H
+#define SOURCE_H
+
+#include <QList>
+
+#include "sink.h"
+#include "samplepack.h"
+
+class Source
+{
+public:
+    /// Virtual destructor. Must be called by implementors to notify sinks.
+    virtual ~Source();
+
+    /// Returns true if source has X data
+    virtual bool hasX() const = 0;
+
+    /// Returns number of channels
+    virtual unsigned numChannels() const = 0;
+
+    /// Connects a sink to this source.
+    ///
+    /// If `Sink` is already connected to a source, it's disconnected first.
+    void connectSink(Sink* sink);
+
+    /// Disconnects an already connected sink. Trying to disconnect an
+    /// unconnected sink is an error.
+    void disconnect(Sink* sink);
+
+    /// Disconnects all connected sinks.
+    void disconnectSinks();
+
+protected:
+    /// Feeds "in" given data to connected sinks
+    virtual void feedOut(const SamplePack& data) const;
+
+    /// Updates "number of channels" of connected sinks. Must be
+    /// called when num. channels or hasX changes.
+    void updateNumChannels() const;
+
+private:
+    QList<Sink*> sinks;
+};
+
+#endif // SOURCE_H