1 files changed, 78 insertions, 0 deletions
diff --git a/boost/geometry/util/select_sequence_element.hpp b/boost/geometry/util/select_sequence_element.hpp
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+++ b/boost/geometry/util/select_sequence_element.hpp
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+// Boost.Geometry
+
+// Copyright (c) 2017 Adam Wulkiewicz, Lodz, Poland.
+
+// Use, modification and distribution is subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_GEOMETRY_UTIL_SELECT_SEQUENCE_ELEMENT
+#define BOOST_GEOMETRY_UTIL_SELECT_SEQUENCE_ELEMENT
+
+
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/int.hpp>
+#include <boost/mpl/at.hpp>
+#include <boost/mpl/size.hpp>
+
+#include <boost/type_traits/is_same.hpp>
+
+#include <boost/geometry/core/coordinate_type.hpp>
+#include <boost/geometry/util/select_most_precise.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+namespace util
+{
+
+template <typename Curr, typename Next>
+struct pred_more_precise_coordinate_type
+{
+    typedef typename geometry::coordinate_type<Curr>::type curr_coord_t;
+    typedef typename geometry::coordinate_type<Next>::type next_coord_t;
+
+    typedef typename boost::mpl::if_c
+        <
+            boost::is_same
+                <
+                    curr_coord_t,
+                    typename select_most_precise
+                        <
+                            curr_coord_t,
+                            next_coord_t
+                        >::type
+                >::value,
+            Curr,
+            Next
+        >::type type;
+};
+
+template
+<
+    typename Seq,
+    template<typename, typename> class Pred = pred_more_precise_coordinate_type,
+    int I = 0,
+    int N = boost::mpl::size<Seq>::value
+>
+struct select_sequence_element
+{
+    typedef typename boost::mpl::at<Seq, boost::mpl::int_<I> >::type curr_t;
+    typedef typename select_sequence_element<Seq, Pred, I+1, N>::type next_t;
+
+    typedef typename Pred<curr_t, next_t>::type type;
+};
+
+template <typename Seq, template<typename, typename> class Pred, int N>
+struct select_sequence_element<Seq, Pred, N, N>
+{
+    typedef typename boost::mpl::at<Seq, boost::mpl::int_<N-1> >::type type;
+};
+
+} // namespace util
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_UTIL_SELECT_SEQUENCE_ELEMENT