the begginning

utils/windowfunction/wf_nth_value.h

@@ -0,0 +1,60 @@
+/* Copyright (C) 2014 InfiniDB, Inc.
+
+   This program 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; version 2 of
+   the License.
+
+   This program 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 this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+
+//  $Id: wf_nth_value.h 3868 2013-06-06 22:13:05Z xlou $
+
+
+#ifndef UTILS_WF_NTH_VALUE_H
+#define UTILS_WF_NTH_VALUE_H
+
+#include "windowfunctiontype.h"
+
+
+namespace windowfunction
+{
+
+
+template<typename T>
+class WF_nth_value : public WindowFunctionType
+{
+public:
+	WF_nth_value(int id, const std::string& name) : WindowFunctionType(id, name) {resetData();}
+
+	// pure virtual in base
+	void operator()(int64_t b, int64_t e, int64_t c);
+	WindowFunctionType* clone() const;
+	void resetData();
+	void parseParms(const std::vector<execplan::SRCP>&);
+
+	static boost::shared_ptr<WindowFunctionType> makeFunction(int, const string&, int);
+
+protected:
+	T           fValue;
+	int64_t     fNth;
+	bool        fNthNull;
+	bool        fFromFirst;     // from first | from last
+	bool        fRespectNulls;  // respect null | ignore null
+
+};
+
+
+} // namespace
+
+#endif  // UTILS_WF_NTH_VALUE_H
+
+// vim:ts=4 sw=4:
+