[BL] added metaprogramming integer sequence

BaseLib/TMPUtil.h

+/**
+ * \copyright
+ * Copyright (c) 2012-2016, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#ifndef BASELIB_TMPUTIL_H
+#define BASELIB_TMPUTIL_H
+
+namespace BaseLib
+{
+//! Has sequence of integers as template parameters
+template <int...>
+struct IntegerSequence {
+};
+
+//! Generates an IntegerSequence.
+//!
+//! \see http://stackoverflow.com/a/7858971
+template <int N, int... S>
+struct GenerateIntegerSequence {
+    // effectively pushes N-1 from the left to the list int... S of integers.
+    typedef typename GenerateIntegerSequence<N - 1, N - 1, S...>::type type;
+};
+
+template <int... S>
+struct GenerateIntegerSequence<0, S...> {
+    typedef IntegerSequence<S...> type;
+};
+/* The template metaprogram proceeds in the following way:
+ *
+ * GenerateIntegerSequence<sizeof...(Args)>::type
+ *
+ * Assume sizeof...(Args) == 3. Let GIS := GenerateIntegerSequence
+ * GIS<3, []>
+ * -> GIS<2, [2]>
+ * -> GIS<1, [1, 2]>
+ * -> GIS<0, [0, 1, 2], which has member typedef IntegerSequence<0, 1, 2>
+ */
+
+}  // namespace BaseLib
+
+#endif  // BASELIB_TMPUTIL_H