make getNumberOfComponents a free function for functions. Update the Function concept

Author: thelfer

include/MGIS/Function/FixedSizeModifier.ixx

@@ -16,7 +16,7 @@ namespace mgis::function {
   requires(N > 0)  //
       constexpr bool FixedSizeModifier<EvaluatorType, N>::checkPreconditions(
           AbstractErrorHandler& eh, const EvaluatorType& values) {
-    if (values.getNumberOfComponents() != N) {
+    if (internals::disambiguateGetNumberOfComponents(values) != N) {
       return eh.registerErrorMessage("invalid number of components");
     }
     return true;

include/MGIS/Function/FixedSizeView.ixx

@@ -16,7 +16,7 @@ namespace mgis::function {
   requires(N > 0)  //
       constexpr bool FixedSizeView<FunctionType, N>::checkPreconditions(
           AbstractErrorHandler& eh, const FunctionType& values) {
-    if (values.getNumberOfComponents() != N) {
+    if (internals::disambiguateGetNumberOfComponents(values) != N) {
       return eh.registerErrorMessage("invalid number of components");
     }
     return true;

include/MGIS/Function/FunctionConcept.hxx

@@ -234,6 +234,9 @@ namespace mgis::function {
   concept FunctionConcept =
       (SpaceConcept<
           std::decay_t<decltype(getSpace(std::declval<FunctionType>()))>>)&&  //
+      (requires(const FunctionType& e) {
+        { getNumberOfComponents(e) } -> std::same_as<mgis::size_type>;
+      }) &&
       ((internals::FunctionResultQuery<FunctionType>::b1) ||
        (internals::FunctionResultQuery<FunctionType>::b2) ||
        (internals::FunctionResultQuery<FunctionType>::b3) ||
@@ -341,6 +344,14 @@ namespace mgis::function {
     template <FunctionConcept FunctionType>
     constexpr decltype(auto) disambiguateGetSpace(const FunctionType&)  //
         requires(!EvaluatorConcept<FunctionType>);
+    /*!
+     * This helper function allows to disambiguate the call to
+     * the getNumberOfComponents function
+     */
+    template <FunctionConcept FunctionType>
+    constexpr mgis::size_type disambiguateGetNumberOfComponents(
+        const FunctionType&)  //
+        requires(!EvaluatorConcept<FunctionType>);
 
     /*!
      * \brief number of components of a type when known at compile-time,

include/MGIS/Function/FunctionConcept.ixx

@@ -17,7 +17,14 @@ namespace mgis::function::internals {
   constexpr decltype(auto) disambiguateGetSpace(const FunctionType& f)  //
       requires(!EvaluatorConcept<FunctionType>) {
     return getSpace(f);
-  }
+  } // end of disambiguateGetSpace
+
+  template <FunctionConcept FunctionType>
+  constexpr mgis::size_type disambiguateGetNumberOfComponents(
+      const FunctionType& f)  //
+      requires(!EvaluatorConcept<FunctionType>) {
+    return getNumberOfComponents(f);
+  }  // end of disambiguateGetNumberOfComponents
 
 }  // end of namespace mgis::function::internals
 

include/MGIS/Function/Tensors/TensorView.ixx

@@ -15,7 +15,7 @@ namespace mgis::function {
   template <FunctionConcept FunctionType, TensorConcept TensorType>
   constexpr bool TensorView<FunctionType, TensorType>::checkPreconditions(
       AbstractErrorHandler& eh, const FunctionType& values) {
-    const auto nc = values.getNumberOfComponents();
+    const auto nc = internals::disambiguateGetNumberOfComponents(values);
     if (nc != compile_time_size<TensorType>) {
       return eh.registerErrorMessage("invalid number of components");
     }