Implement is_pointer, is_lvalue_reference, remove_pointer

These are replacements for TypeTraits::isPointer, TypeTraits::isReference,
TypeTraits::PointeeType.  They reimplement what is available in the
C++11 standard library, and are expected to supersede the TypeTraits
class eventually.

Note: this patch does not pull in the corresponding stl implementation.

dune/common/test/typetraitstest.cc

@@ -39,5 +39,34 @@ int main() {
   assert( (Dune::is_same<int, Dune::TypeTraits<int>::ReferredType>::value) );
   assert( (Dune::is_same<int, Dune::TypeTraits<int&>::ReferredType>::value) );
 
+  // Test is_pointer
+  assert( not Dune::is_pointer<int>::value );
+  assert(     Dune::is_pointer<int*>::value );
+  assert(     Dune::is_pointer<int**>::value );
+  assert(     Dune::is_pointer<int(*)(int)>::value );
+
+  // Test is_reference
+  assert( not Dune::is_lvalue_reference<int>::value );
+  assert(     Dune::is_lvalue_reference<int&>::value );
+#if HAVE_RVALUE_REFERENCES
+  assert( not Dune::is_lvalue_reference<int&&>::value );
+#endif
+
+  // Test remove_pointer
+  // Note: when the argument T is not a pointer, TypeTraits::PointeeType returns Dune::Empty,
+  // while Dune::remove_pointer (as std::remove_pointer), returns T itself
+  assert( (Dune::is_same<int,       Dune::remove_pointer<int>::type>::value) );
+  assert( (Dune::is_same<int,       Dune::remove_pointer<int*>::type>::value) );
+  assert( (Dune::is_same<int*,      Dune::remove_pointer<int**>::type>::value) );
+  assert( (Dune::is_same<const int, Dune::remove_pointer<const int*>::type>::value) );
+  assert( (Dune::is_same<int,       Dune::remove_pointer<int* const>::type>::value) );
+
+  // Test remove_reference
+  assert( (Dune::is_same<int, Dune::remove_reference<int>::type>::value) );
+  assert( (Dune::is_same<int, Dune::remove_reference<int&>::type>::value) );
+#if HAVE_RVALUE_REFERENCES
+  assert( (Dune::is_same<int, Dune::remove_reference<int&&>::type>::value) );
+#endif
+
   return 0;
 }

dune/common/typetraits.hh

@@ -32,6 +32,12 @@ namespace Dune
   /**
    * @brief General type traits class to check whether type is reference or
    * pointer type
+   *
+   * \deprecated This class will be replaced by alternatives found in the C++11 stl.
+   *   - Use is_pointer<T>::value instead of TypeTraits<T>::isPointer
+   *   - Use is_lvalue_reference<T>::value instead of TypeTraits<T>::isReference
+   *   - Use remove_pointer<T>::type instead of TypeTraits<T>::PointeeType
+   *   - Use remove_reference<T>::type instead of TypeTraits<T>::ReferredType
    */
   template <typename T>
   class TypeTraits
@@ -465,6 +471,53 @@ namespace Dune
   typedef integral_constant<bool, false> false_type;
 #endif // #else // #if HAVE_INTEGRAL_CONSTANT
 
+  template<typename>
+  struct __is_pointer_helper
+  : public false_type { };
+
+  template<typename T>
+  struct __is_pointer_helper<T*>
+  : public true_type { };
+
+  /// is_pointer
+  template<typename T>
+  struct is_pointer
+  : public integral_constant<bool, (__is_pointer_helper<T>::value)>
+    { };
+
+  // Helper class for is_lvalue_reference
+  template<typename>
+  struct __is_lvalue_reference_helper
+  : public false_type { };
+
+  template<typename T>
+  struct __is_lvalue_reference_helper<T&>
+  : public true_type { };
+
+  /** \brief Determine whether a type is a lvalue reference type */
+  template<typename T>
+  struct is_lvalue_reference
+  : public integral_constant<bool, (__is_lvalue_reference_helper<T>::value)>
+    { };
+
+  template<typename _Tp>
+    struct __remove_pointer_helper
+    { typedef _Tp     type; };
+
+  template<typename _Tp>
+    struct __remove_pointer_helper<_Tp*>
+    { typedef _Tp     type; };
+
+  /** \brief Return the type a pointer type points to
+   *
+   * \note When the argument T is not a pointer, TypeTraits::PointeeType returns Dune::Empty,
+   * while Dune::remove_pointer (as std::remove_pointer), returns T itself.
+   */
+  template<typename _Tp>
+    struct remove_pointer
+    : public __remove_pointer_helper<typename remove_const<_Tp>::type >
+    { };
+
   /** @} */
 }
 #endif