From 11a1c26494dc09f3dd713a1efee448805bda87cb Mon Sep 17 00:00:00 2001
From: Anton Bachin <antonbachin@yahoo.com>
Date: Fri, 12 Jun 2015 12:56:51 -0500
Subject: [PATCH] Internal improvements to stream operators.

---
 enum.h | 42 +++++++++++++++---------------------------
 1 file changed, 15 insertions(+), 27 deletions(-)

diff --git a/enum.h b/enum.h
index 02e7345..91b9289 100644
--- a/enum.h
+++ b/enum.h
@@ -1041,49 +1041,37 @@ BETTER_ENUMS__CONSTEXPR inline bool operator !=(const Enum &a, const Enum &b)  \
 
 namespace better_enums {
 
-// This template is used both as a sort of enable_if for SFINAE, and to delay
-// the compiler from type-checking certain expressions. enum.h does not include
-// <iostream> or <string>, because those headers parse very slowly. Therefore,
-// it is necessary to prevent the compiler from trying to do anything with types
-// from those headers unless the operators <<, >> are actually used, by which
-// point the user is expected to have included <iostream> and/or <string>. The
-// alternative is to simply move the operator definitions into a separate add-on
-// header file.
-//
-// It should be possible to use std::enable_if, however <type_traits> is not
-// available in C++98.
+// This template is used as a sort of enable_if for SFINAE. It should be
+// possible to use std::enable_if, however <type_traits> is not available in
+// C++98. Non-char streams are currently not supported.
 template <typename T, typename Enum>
-struct hide { typedef T type; };
+struct only_if_enum { typedef T type; };
 
 }
 
-template <typename Enum>
-inline typename better_enums::hide<std::ostream,
-                                   typename Enum::_enumerated>::type&
-operator <<(std::ostream& stream, const Enum& value)
+template <typename Char, typename Traits, typename Enum>
+inline typename better_enums::only_if_enum<std::basic_ostream<Char, Traits>,
+                                           typename Enum::_enumerated>::type&
+operator <<(std::basic_ostream<Char, Traits>& stream, const Enum &value)
 {
     return stream << value._to_string();
 }
 
-template <typename Enum>
-inline typename better_enums::hide<std::istream,
-                                   typename Enum::_enumerated>::type&
-operator >>(typename better_enums::hide<std::istream, Enum>::type& stream,
-            Enum& value)
+template <typename Char, typename Traits, class Enum>
+inline typename better_enums::only_if_enum<std::basic_istream<Char, Traits>,
+                                           typename Enum::_enumerated>::type&
+operator >>(std::basic_istream<Char, Traits>& stream, Enum &value)
 {
-    typedef typename better_enums::hide<std::ios_base, Enum>::type  ios_base;
-    typedef typename better_enums::hide<std::string,   Enum>::type  string;
-
-    string      buffer;
+    std::basic_string<Char, Traits>     buffer;
 
     stream >> buffer;
-    better_enums::optional<Enum>  converted =
+    better_enums::optional<Enum>        converted =
         Enum::_from_string_nothrow(buffer.c_str());
 
     if (converted)
         value = *converted;
     else
-        stream.setstate(ios_base::failbit);
+        stream.setstate(std::basic_istream<Char, Traits>::failbit);
 
     return stream;
 }