[!241] MultiTypeBlockVector: Inherit tuple constructors

Merge branch 'feature/mtbv-inherit-tuple-constructors' into 'master'

ref:core/dune-istl

-   Makes member function count const
-   Inherits tuple constructors so that MultiTypeBlockVector can be
    constructed from existing Vectors, or we can even construct it with
    references to existing vectors.
-   Test construction from references in the test
-   Fixes the static_assert in the test that shouldn't really have compiled
    before

See merge request [!241]

  [!241]: gitlab.dune-project.org/core/dune-istl/merge_requests/241

CHANGELOG.md

@@ -11,6 +11,12 @@
 - Support for SuiteSparse's CHOLMOD providing a sparse Cholesky
   factorization.
 
+- `MultiTypeBlockVector<Args...>` now inherits the constructors from its
+  parent type (`std::tuple<Args...>`). This means you can now also construct
+  `MultiTypeBlockVector`s from values or references of BlockVectors.
+
+- `MultiTypeBlockVector::count()` is now `const`
+
 # Release 2.6
 
 - `BDMatrix` objects can now be constructed and assigned from `std::initializer_list`.

dune/istl/multitypeblockvector.hh

@@ -55,9 +55,14 @@ namespace Dune {
   : public std::tuple<Args...>
   {
     /** \brief Helper type */
-    typedef std::tuple<Args...> tupleType;
+    typedef std::tuple<Args...> TupleType;
   public:
 
+    /**
+     * \brief Get the constructors from tuple
+     */
+    using TupleType::TupleType;
+
     /**
      * own class' type
      */
@@ -81,7 +86,7 @@ namespace Dune {
     /**
      * number of elements
      */
-    int count()
+    int count() const
     {
       return sizeof...(Args);
     }
@@ -105,7 +110,7 @@ namespace Dune {
      * \endcode
      */
     template< std::size_t index >
-    typename std::tuple_element<index,tupleType>::type&
+    typename std::tuple_element<index,TupleType>::type&
     operator[] ( const std::integral_constant< std::size_t, index > indexVariable )
     {
       DUNE_UNUSED_PARAMETER(indexVariable);
@@ -118,7 +123,7 @@ namespace Dune {
      * explanation of how to use it.
      */
     template< std::size_t index >
-    const typename std::tuple_element<index,tupleType>::type&
+    const typename std::tuple_element<index,TupleType>::type&
     operator[] ( const std::integral_constant< std::size_t, index > indexVariable ) const
     {
       DUNE_UNUSED_PARAMETER(indexVariable);

dune/istl/test/multitypeblockvectortest.cc

@@ -14,74 +14,92 @@
 #include <dune/common/exceptions.hh>
 #include <dune/common/fvector.hh>
 #include <dune/common/indices.hh>
+#include <dune/common/float_cmp.hh>
 
 #include <dune/istl/bvector.hh>
 #include <dune/istl/multitypeblockvector.hh>
 
 using namespace Dune;
 
-int main(int argc, char** argv) try
+template<typename... Args>
+void testMultiVector(const MultiTypeBlockVector<Args...>& multiVector)
 {
-  using namespace Indices;
+    // test operator<<
+    std::cout << multiVector << std::endl;
 
-  MultiTypeBlockVector<BlockVector<FieldVector<double,3> >, BlockVector<FieldVector<double,1> > > multiVector;
+    // test method 'count'
+    std::cout << "multi vector has " << multiVector.count() << " first level blocks" << std::endl;
 
-  multiVector[_0] = {{1,0,0},
-                     {0,1,0},
-                     {0,0,1}};
+    static_assert(MultiTypeBlockVector<Args...>::size()==2, "Method MultiTypeBlockVector::size() returned wrong value!");
 
-  multiVector[_1] = {3.14, 42};
+    if (multiVector.count() != 2)
+      DUNE_THROW(Exception, "Method MultiTypeBlockVector::count returned wrong value!");
+
+    // Test copy construction
+    auto multiVector2 = multiVector;
 
-  // test operator<<
-  std::cout << multiVector << std::endl;
+    // Test assignment operator
+    multiVector2 = multiVector;
 
-  // test method 'count'
-  std::cout << "multi vector has " << multiVector.count() << " first level blocks" << std::endl;
+    // Test operator+=
+    multiVector2 += multiVector;
 
-  static_assert(multiVector.size()==2, "Method MultiTypeBlockVector::size() returned wrong value!");
+    // Test operator-=
+    multiVector2 -= multiVector;
 
-  if (multiVector.count() != 2)
-    DUNE_THROW(Exception, "Method MultiTypeBlockVector::count returned wrong value!");
+    // Test multiplication with scalar
+    multiVector2 *= (double)0.5;
+    multiVector2 *= (int)2;
+    multiVector2 *= (float)0.5;
 
-  // Test copy construction
-  auto multiVector2 = multiVector;
+    // Test assignment from scalar
+    multiVector2 = (double)0.5;
+    multiVector2 = (int)2;
+    multiVector2 = (float)0.5;
 
-  // Test assignment operator
-  multiVector2 = multiVector;
+    // Test axpy
+    multiVector2.axpy(-1, multiVector);
 
-  // Test operator+=
-  multiVector2 += multiVector;
+    // Test two_norm
+    std::cout << "multivector2 has two_norm: " << multiVector2.two_norm() << std::endl;
 
-  // Test operator-=
-  multiVector2 -= multiVector;
+    // Test two_norm2
+    std::cout << "multivector2 has two_norm2: " << multiVector2.two_norm2() << std::endl;
 
-  // Test multiplication with scalar
-  multiVector2 *= (double)0.5;
-  multiVector2 *= (int)2;
-  multiVector2 *= (float)0.5;
+    // Test infinity_norm
+    std::cout << "multivector2 has infinity_norm: " << multiVector2.infinity_norm() << std::endl;
 
-  // Test assignment from scalar
-  multiVector2 = (double)0.5;
-  multiVector2 = (int)2;
-  multiVector2 = (float)0.5;
+    // Test operator*
+    std::cout << multiVector * multiVector2 << std::endl;
 
-  // Test axpy
-  multiVector2.axpy(-1, multiVector);
+    // Test method 'dot'
+    std::cout << multiVector.dot(multiVector2) << std::endl;
+}
+
+int main(int argc, char** argv) try
+{
+  using namespace Indices;
+
+  MultiTypeBlockVector<BlockVector<FieldVector<double,3> >, BlockVector<FieldVector<double,1> > > multiVector;
+
+  multiVector[_0] = {{1,0,0},
+                     {0,1,0},
+                     {0,0,1}};
+
+  multiVector[_1] = {3.14, 42};
 
-  // Test two_norm
-  std::cout << "multivector2 has two_norm: " << multiVector2.two_norm() << std::endl;
+  testMultiVector(multiVector);
 
-  // Test two_norm2
-  std::cout << "multivector2 has two_norm2: " << multiVector2.two_norm2() << std::endl;
+  // create a "shallow" copy
+  MultiTypeBlockVector<BlockVector<FieldVector<double,3> >&, BlockVector<FieldVector<double,1> >& >
+    multiVectorRef(multiVector[_0], multiVector[_1]);
 
-  // Test infinity_norm
-  std::cout << "multivector2 has infinity_norm: " << multiVector2.infinity_norm() << std::endl;
+  multiVectorRef[_0][0][0] = 5.0;
 
-  // Test operator*
-  std::cout << multiVector * multiVector2 << std::endl;
+  if (!FloatCmp::eq(multiVectorRef[_0][0][0], multiVector[_0][0][0]))
+    DUNE_THROW(Exception, "Modifying an entry of the referencing vector failed!");
 
-  // Test method 'dot'
-  std::cout << multiVector.dot(multiVector2) << std::endl;
+  testMultiVector(multiVectorRef);
 
   return 0;
 }