Updating ...

src/tools/ranges/ViewBase.hpp

@@ -40,55 +40,60 @@ class ViewBase {
   /**
    *  @brief Return whether or not the view is empty
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
   constexpr bool empty() const noexcept {
 
+    static_assert(
+      concepts::IsForwardIterator< typename Derived::iterator >::value == true,
+      "the empty() method can only be made available for forward iterators" );
+
     return this->derived().begin() == this->derived().end();
   }
 
   /**
    *  @brief Return whether or not the view is empty
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
   constexpr explicit operator bool() const noexcept {
 
+    static_assert(
+      concepts::IsForwardIterator< typename Derived::iterator >::value == true,
+      "the operator bool() method can only be made available for forward iterators" );
+
     return this->empty();
   }
 
   /**
    *  @brief Return the size of the iterator view
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
   constexpr std::size_t size() const noexcept {
 
+    static_assert(
+      concepts::IsForwardIterator< typename Derived::iterator >::value == true,
+      "the size() method can only be made available for forward iterators" );
+
     return std::distance( this->derived().begin(), this->derived().end() );
   }
 
   /**
    *  @brief Return the reference to the front element of the view
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
   constexpr decltype(auto) front() const noexcept {
 
+    static_assert(
+      concepts::IsForwardIterator< typename Derived::iterator >::value == true,
+      "the front() method can only be made available for forward iterators" );
+
     return *( this->derived().begin() );
   }
 
   /**
    *  @brief Return the reference to the back element of the view
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsBidirectionalIterator,
-                                 typename Range::iterator > = true >
   constexpr decltype(auto) back() const noexcept {
 
+    static_assert(
+      concepts::IsBidirectionalIterator< typename Derived::iterator >::value == true,
+      "the back() method can only be made available for bidirectional iterators" );
+
     return *( std::prev( this->derived().end() ) );
   }
 
@@ -99,11 +104,12 @@ class ViewBase {
    *
    *  @param[in] i    the index
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsRandomAccessIterator,
-                                 typename Range::iterator > = true >
   constexpr decltype(auto) operator[]( std::size_t i ) const noexcept {
 
+    static_assert(
+      concepts::IsRandomAccessIterator< typename Derived::iterator >::value == true,
+      "the operator[] method can only be made available for random access iterators" );
+
     return *( std::next( this->derived().begin(), i ) );
   }
 
@@ -112,11 +118,12 @@ class ViewBase {
    *
    *  @param[in] i    the index
    */
-  template < typename Range = Derived,
-             concepts::Requires< true, concepts::IsRandomAccessIterator,
-                                 typename Range::iterator > = true >
   constexpr decltype(auto) at( std::size_t i ) const {
 
+    static_assert(
+      concepts::IsRandomAccessIterator< typename Derived::iterator >::value == true,
+      "the at() method can only be made available for random access iterators" );
+
     if ( i >= this->size() ) {
 
       throw std::out_of_range( "Index out of range: " +
@@ -154,85 +161,6 @@ class ViewBase {
 
     return !this->operator==( other );
   }
-
-  // the following code is added to make compiler errors more comprehensible
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
-  constexpr bool empty() const noexcept {
-
-    static_assert(
-      concepts::IsForwardIterator< typename Range::iterator >::value == true,
-      "the empty() method can only be made available for forward iterators" );
-    return true;
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
-  constexpr explicit operator bool() const noexcept {
-
-    static_assert(
-      concepts::IsForwardIterator< typename Range::iterator >::value == true,
-      "the operator bool() method can only be made available for forward iterators" );
-    return true;
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
-  constexpr std::size_t size() const noexcept {
-
-    static_assert(
-      concepts::IsForwardIterator< typename Range::iterator >::value == true,
-      "the size() method can only be made available for forward iterators" );
-    return std::size_t{};
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsForwardIterator,
-                                 typename Range::iterator > = true >
-  constexpr decltype(auto) front() const noexcept {
-
-    static_assert(
-      concepts::IsBidirectionalIterator< typename Range::iterator >::value == true,
-      "the front() method can only be made available for bidirectional iterators" );
-    return typename Derived::value_type{};
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsBidirectionalIterator,
-                                 typename Range::iterator > = true >
-  constexpr decltype(auto) back() const noexcept {
-
-    static_assert(
-      concepts::IsBidirectionalIterator< typename Range::iterator >::value == true,
-      "the back() method can only be made available for bidirectional iterators" );
-    return typename Derived::value_type{};
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsRandomAccessIterator,
-                                 typename Range::iterator > = true >
-  constexpr decltype(auto) operator[]( std::size_t i ) const {
-
-    static_assert(
-      concepts::IsRandomAccessIterator< typename Range::iterator >::value == true,
-      "the operator[] method can only be made available for random access iterators" );
-    return typename Derived::value_type{};
-  }
-
-  template < typename Range = Derived,
-             concepts::Requires< false, concepts::IsRandomAccessIterator,
-                                 typename Range::iterator > = true >
-  constexpr decltype(auto) at( std::size_t i ) const {
-
-    static_assert(
-      concepts::IsRandomAccessIterator< typename Range::iterator >::value == true,
-      "the at() method can only be made available for random access iterators" );
-    return typename Derived::value_type{};
-  }
 };
 
 } // ranges namespace