make range_iterator, range_difference, and range_size SFINAE-friendly, refs #11187

include/boost/range/difference_type.hpp

@@ -15,20 +15,37 @@
 # pragma once
 #endif
 
+#include <boost/mpl/and.hpp>
 #include <boost/range/config.hpp>
 #include <boost/range/iterator.hpp>
+#include <boost/range/has_range_iterator.hpp>
 #include <boost/iterator/iterator_traits.hpp>
 #include <boost/type_traits/remove_reference.hpp>
 
 namespace boost
 {
+    namespace range_detail
+    {
+        template< class T, class Enabler=void >
+        struct range_difference
+        { };
+
+        template< class T >
+        struct range_difference<
+            T,
+            BOOST_DEDUCED_TYPENAME ::boost::enable_if_c<
+                has_type<range_iterator<T> >::value
+            >::type
+        >
+          : iterator_difference<
+                BOOST_DEDUCED_TYPENAME range_iterator<T>::type
+            >
+        { };
+    }
+
     template< class T >
     struct range_difference
-            : iterator_difference<
-                BOOST_DEDUCED_TYPENAME range_iterator<
-                    BOOST_DEDUCED_TYPENAME remove_reference<T>::type
-                >::type
-            >
+      : range_detail::range_difference<BOOST_DEDUCED_TYPENAME remove_reference<T>::type>
     { };
 }
 

include/boost/range/iterator.hpp

@@ -46,31 +46,29 @@ namespace boost
        };       
     }  
     
-#endif  
-
     template< typename C, typename Enabler=void >
     struct range_iterator
     {
-#if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
-  
+
         typedef BOOST_RANGE_DEDUCED_TYPENAME  
                range_detail_vc7_1::range_iterator<C>::type type;  
-           
-#else  
 
-    private:
-        typedef typename remove_reference<C>::type param_t;
-
-    public:
-        typedef typename mpl::eval_if_c<
-            is_const<param_t>::value,
-            range_const_iterator<typename remove_const<param_t>::type>,
-            range_mutable_iterator<param_t>
-        >::type type;
-        
-#endif         
     };
-    
+
+#else
+
+    template< typename C, typename Enabler=void >
+    struct range_iterator
+      : mpl::if_c<
+            is_const<typename remove_reference<C>::type>::value,
+            range_const_iterator<typename remove_const<typename remove_reference<C>::type>::type>,
+            range_mutable_iterator<typename remove_reference<C>::type>
+        >::type
+    {
+    };
+
+#endif
+
 } // namespace boost
 
 #endif

include/boost/range/size_type.hpp

@@ -18,6 +18,7 @@
 #include <boost/range/config.hpp>
 #include <boost/range/difference_type.hpp>
 #include <boost/range/concepts.hpp>
+#include <boost/range/has_range_iterator.hpp>
 
 #include <boost/utility/enable_if.hpp>
 #include <boost/type_traits/make_unsigned.hpp>
@@ -51,7 +52,7 @@ namespace boost
         };
 
         template<typename C, typename Enabler=void>
-        struct range_size
+        struct range_size_
         {
             typedef BOOST_DEDUCED_TYPENAME make_unsigned<
                 BOOST_DEDUCED_TYPENAME range_difference<C>::type
@@ -59,7 +60,7 @@ namespace boost
         };
 
         template<typename C>
-        struct range_size<
+        struct range_size_<
             C,
             BOOST_DEDUCED_TYPENAME ::boost::enable_if<has_size_type<C>, void>::type
         >
@@ -67,29 +68,38 @@ namespace boost
             typedef BOOST_DEDUCED_TYPENAME C::size_type type;
         };
 
-    }
+        template<typename C, typename Enabler=void>
+        struct range_size
+        { };
 
-    template< class T >
-    struct range_size :
-        detail::range_size<T>
-    {
+        template<typename C>
+        struct range_size<
+            C,
+            BOOST_DEDUCED_TYPENAME ::boost::enable_if_c<
+                range_detail::has_type< range_iterator<C> >::value
+            >::type
+        >
+          : range_size_<C>
+        {
 // Very strange things happen on some compilers that have the range concept
 // asserts disabled. This preprocessor condition is clearly redundant on a
 // working compiler but is vital for at least some compilers such as clang 4.2
 // but only on the Mac!
 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT == 1
-        BOOST_RANGE_CONCEPT_ASSERT((boost::SinglePassRangeConcept<T>));
+            BOOST_RANGE_CONCEPT_ASSERT((boost::SinglePassRangeConcept<C>));
 #endif
-    };
+        };
+    }
 
     template< class T >
-    struct range_size<const T >
-        : detail::range_size<T>
-    {
-#if BOOST_RANGE_ENABLE_CONCEPT_ASSERT == 1        
-        BOOST_RANGE_CONCEPT_ASSERT((boost::SinglePassRangeConcept<T>));
-#endif
-    };
+    struct range_size :
+        detail::range_size<T>
+    { };
+
+    template< class T >
+    struct range_size<const T > :
+        detail::range_size<T>
+    { };
 
 } // namespace boost