Add a hybrid loop over a sparse range

dune/solvers/common/algorithm.hh

@@ -242,6 +242,33 @@ constexpr auto hybridSize(const T& t)
 
 
 
+/**
+ * \brief Hybrid for loop over sparse range
+ */
+template<class... T, class F>
+void sparseRangeFor(Dune::MultiTypeBlockMatrix<T...>& range, F&& f)
+{
+  integralRangeFor<std::size_t>(Indices::_0, hybridSize(range), [&](auto&& i) {
+      f(range[i], i);
+  });
+}
+
+
+
+/**
+ * \brief Hybrid for loop over sparse range
+ */
+template<class Range, class F>
+void sparseRangeFor(Range&& range, F&& f)
+{
+  auto it = range.begin();
+  auto end = range.end();
+  for(; it!=end; ++it)
+    f(*it, it.index());
+}
+
+
+
 } // namespace Solvers
 } // namespace Dune