Fix compilation on VS2010 (#207)

SergiusTheBest · Apr 26, 2022 · e2650b8 · e2650b8
1 parent 130801c
commit e2650b8
Showing 1 changed file with 45 additions and 8 deletions.
diff --git a/include/plog/Record.h b/include/plog/Record.h
@@ -27,6 +27,43 @@ namespace plog
 
             template<class T>
             struct enableIf<true, T> { typedef T type; };
+
+		    struct No  { char a[1]; };
+            struct Yes { char a[2]; };
+
+            template <class From, class To>
+            struct isConvertible
+            {
+                // `+ sizeof(U*)` is required for GCC 4.5-4.7
+                template<class U>
+                static typename enableIf<!!(sizeof(static_cast<To>(meta::declval<U>())) + sizeof(U*)), Yes>::type test(int);
+
+                template<class U>
+                static No test(...);
+
+                enum { value = sizeof(test<From>(0)) == sizeof(Yes) };
+            };
+
+            template <class T>
+            struct isConvertibleToNString : isConvertible<T, std::basic_string<util::nchar> > {};
+
+            template <class T>
+            struct isContainer
+            {
+                template<class U>
+                static typename meta::enableIf<!!(sizeof(
+#if defined(_MSC_VER) && _MSC_VER < 1700 // MSVC 2010 doesn't understand `typename T::const_iterator`
+                    meta::declval<U>().begin()) + sizeof(meta::declval<U>().end()
+#else
+                    typename U::const_iterator
+#endif
+                    )), Yes>::type test(int);
+
+                template<class U>
+                static No test(...);
+
+                enum { value = sizeof(test<T>(0)) == sizeof(Yes) };
+            };
         }
 
         //////////////////////////////////////////////////////////////////////////
@@ -88,20 +125,20 @@ namespace plog
         }
 
 #if defined(__clang__) || !defined(__GNUC__) || __GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ > 4 // skip for GCC < 4.5 due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38600
-        // Print data that can be casted to `std::basic_string`. `+ sizeof(T*)` is required for GCC 4.5-4.7.
-        template<typename T>
-        inline typename meta::enableIf<!!(sizeof(static_cast<std::basic_string<util::nchar> >(meta::declval<T>())) + sizeof(T*)), void>::type operator<<(util::nostringstream& stream, const T& data)
+        // Print data that can be casted to `std::basic_string`.
+        template<class T>
+        inline typename meta::enableIf<meta::isConvertibleToNString<T>::value, void>::type operator<<(util::nostringstream& stream, const T& data)
         {
             plog::detail::operator<<(stream, static_cast<std::basic_string<util::nchar> >(data));
         }
 
         // Print std containers
-        template<class Container>
-        inline typename meta::enableIf<!!(sizeof(typename Container::const_iterator)), void>::type operator<<(util::nostringstream& stream, const Container& data)
+        template<class T>
+        inline typename meta::enableIf<meta::isContainer<T>::value && !meta::isConvertibleToNString<T>::value, void>::type operator<<(util::nostringstream& stream, const T& data)
         {
             stream << "[";
 
-            for (typename Container::const_iterator it = data.begin(); it != data.end();)
+            for (typename T::const_iterator it = data.begin(); it != data.end();)
             {
                 stream << *it;
 
@@ -129,12 +166,12 @@ namespace plog
         namespace meta
         {
             template<class T, class Stream>
-            inline char operator<<(Stream&, const T&);
+            inline No operator<<(Stream&, const T&);
 
             template <class T, class Stream>
             struct isStreamable
             {
-                enum { value = sizeof(operator<<(meta::declval<Stream>(), meta::declval<const T>())) != sizeof(char) };
+                enum { value = sizeof(operator<<(meta::declval<Stream>(), meta::declval<const T>())) != sizeof(No) };
             };
 
             template <class Stream>