[local.discretefunction] improve performance for fv spaces

dune/gdt/local/discretefunction.hh

@@ -64,12 +64,13 @@ public:
   ConstLocalDiscreteFunction(const SpaceType& spc, const ConstDofVectorType& dof_vector)
     : BaseType()
     , space_(spc.copy())
+    , space_is_fv_(space_->type() == GDT::SpaceType::finite_volume)
     , dof_vector_(dof_vector.localize())
     , basis_(space_->basis().localize())
-    , basis_values_(space_->mapper().max_local_size())
-    , dynamic_basis_values_(space_->mapper().max_local_size())
-    , basis_derivatives_(space_->mapper().max_local_size())
-    , dynamic_basis_derivatives_(space_->mapper().max_local_size())
+    , basis_values_(space_is_fv_ ? 0 : space_->mapper().max_local_size())
+    , dynamic_basis_values_(basis_values_.size())
+    , basis_derivatives_(basis_values_.size())
+    , dynamic_basis_derivatives_(basis_values_.size())
   {}
 
   virtual ~ConstLocalDiscreteFunction() = default;
@@ -119,7 +120,7 @@ public:
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     RangeReturnType result(0);
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       for (size_t ii = 0; ii < r; ++ii)
         result[ii] = dof_vector_[ii];
     } else {
@@ -135,7 +136,7 @@ public:
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     DerivativeRangeReturnType result(0);
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       return result;
     } else {
       basis_->jacobians(point_in_reference_element, basis_derivatives_, param);
@@ -150,7 +151,7 @@ public:
                                        const XT::Common::Parameter& /*param*/ = {}) const override final
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
-    DUNE_THROW_IF(space_->type() != GDT::SpaceType::finite_volume,
+    DUNE_THROW_IF(space_is_fv_,
                   Exceptions::discrete_function_error,
                   "arbitrary derivatives are not supported by the local finite elements!\n\n"
                       << "alpha = " << alpha << "\n"
@@ -182,11 +183,11 @@ public:
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     RangeSelector::ensure_size(result);
-    result *= 0;
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       for (size_t ii = 0; ii < r; ++ii)
         result[ii] = dof_vector_[ii];
     } else {
+      result *= 0;
       basis_->evaluate(point_in_reference_element, dynamic_basis_values_, param);
       for (size_t ii = 0; ii < basis_->size(); ++ii)
         result.axpy(dof_vector_[ii], dynamic_basis_values_[ii]);
@@ -200,7 +201,7 @@ public:
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     DerivativeRangeSelector::ensure_size(result);
     result *= 0;
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       return;
     } else {
       basis_->jacobians(point_in_reference_element, dynamic_basis_derivatives_, param);
@@ -215,7 +216,7 @@ public:
                   const XT::Common::Parameter& /*param*/ = {}) const override final
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
-    DUNE_THROW_IF(space_->type() != GDT::SpaceType::finite_volume,
+    DUNE_THROW_IF(space_is_fv_,
                   Exceptions::discrete_function_error,
                   "arbitrary derivatives are not supported by the local finite elements!\n\n"
                       << "alpha = " << alpha << "\n"
@@ -248,7 +249,7 @@ public:
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     this->assert_correct_dims(row, col, "evaluate");
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       return dof_vector_[row];
     } else {
       R result(0);
@@ -266,7 +267,7 @@ public:
   {
     DUNE_THROW_IF(!this->is_bound_, Exceptions::not_bound_to_an_element_yet, "");
     this->assert_correct_dims(row, col, "jacobian");
-    if (space_->type() == GDT::SpaceType::finite_volume) {
+    if (space_is_fv_) {
       return 0;
     } else {
       SingleDerivativeRangeReturnType result(0);
@@ -281,6 +282,7 @@ public:
 
 private:
   std::unique_ptr<const SpaceType> space_;
+  const bool space_is_fv_;
   ConstLocalDofVectorType dof_vector_;
   std::unique_ptr<LocalBasisType> basis_;
   mutable std::vector<RangeType> basis_values_;