Merge branch 'feature/partial-const' into 'master'

[common][partial] Add MTBV containing const references

See merge request !2215

dumux/common/partial.hh

@@ -42,6 +42,17 @@ auto partial(Dune::MultiTypeBlockVector<Args...>& v, Dune::index_constant<i>...
     return Dune::MultiTypeBlockVector<std::add_lvalue_reference_t<std::decay_t<std::tuple_element_t<indices, std::tuple<Args...>>>>...>(v[indices]...);
 }
 
+/*!
+ * \brief a function to get a MultiTypeBlockVector with const references to some entries of another MultiTypeBlockVector
+ * \param v a MultiTypeBlockVector
+ * \param indices the indices of the entries that should be referenced
+ */
+template<class ...Args, std::size_t ...i>
+auto partial(const Dune::MultiTypeBlockVector<Args...>& v, Dune::index_constant<i>... indices)
+{
+    return Dune::MultiTypeBlockVector<std::add_lvalue_reference_t<const std::decay_t<std::tuple_element_t<indices, std::tuple<Args...>>>>...>(v[indices]...);
+}
+
 /*!
  * \brief a function to get a tuple with references to some entries of another tuple
  * \param v a tuple
@@ -53,6 +64,17 @@ auto partial(std::tuple<Args...>& v, Dune::index_constant<i>... indices)
     return std::tuple<std::add_lvalue_reference_t<std::decay_t<std::tuple_element_t<indices, std::tuple<Args...>>>>...>(std::get<indices>(v)...);
 }
 
+/*!
+ * \brief a function to get a tuple with const references to some entries of another tuple
+ * \param v a tuple
+ * \param indices a tuple of indices of the entries that should be referenced
+ */
+template<class ...Args, std::size_t ...i>
+auto partial(const std::tuple<Args...>& v, Dune::index_constant<i>... indices)
+{
+    return std::tuple<std::add_lvalue_reference_t<const std::decay_t<std::tuple_element_t<indices, std::tuple<Args...>>>>...>(std::get<indices>(v)...);
+}
+
 /*!
  * \brief a function to get a MultiTypeBlockVector with references to some entries of another MultiTypeBlockVector
  * \param t an std::tuple or Dune::MultiTypeBlockVector

test/common/test_partial.cc

@@ -2,6 +2,7 @@
 
 #include <iostream>
 #include <tuple>
+#include <type_traits>
 
 #include <dune/common/indices.hh>
 #include <dune/common/classname.hh>
@@ -48,6 +49,24 @@ void runTest()
 
     if (!Dune::FloatCmp::eq(std::get<2>(m)[0][0], 5.0))
         DUNE_THROW(Dune::Exception, "Modifying referenced partial vector failed! (m = " << std::get<2>(m)[0][0] << ", p = " << std::get<1>(p)[0][0] << ")");
+
+    const auto mConst = m;
+    auto pConst = partial(mConst, _0, _2);
+    static_assert(std::is_const_v<std::remove_reference_t<decltype(std::get<0>(pConst))>>);
+    static_assert(std::is_const_v<std::remove_reference_t<decltype(std::get<1>(pConst))>>);
+
+    if (!Dune::FloatCmp::eq(std::get<0>(mConst)[0][0], std::get<0>(pConst)[0][0]))
+        DUNE_THROW(Dune::Exception, "Values differ! (mConst = " << std::get<0>(mConst)[0][0] << ", pConst = " << std::get<0>(pConst)[0][0] << ")");
+
+    const auto& mConstRef = m;
+    auto pConstRef = partial(mConstRef, _0, _2);
+    static_assert(std::is_const_v<std::remove_reference_t<decltype(std::get<0>(pConstRef))>>);
+    static_assert(std::is_const_v<std::remove_reference_t<decltype(std::get<1>(pConstRef))>>);
+
+    std::get<2>(m)[0][0] = 10.0;
+
+    if (!Dune::FloatCmp::eq(std::get<1>(pConstRef)[0][0], 10.0))
+        DUNE_THROW(Dune::Exception, "Modifying referenced partial vector failed! (m = " << std::get<2>(m)[0][0] << ", pConstRef = " << std::get<1>(pConstRef)[0][0] << ")");
 }
 
 } // end namespace Dumux
@@ -60,7 +79,6 @@ int main(int argc, char* argv[]) try
     runTest<std::tuple>();
 
     return 0;
-
 }
 catch (const Dune::Exception& e)
 {