From 8a9252826187085da4db5398a2c30d2c7672223a Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Sun, 23 Dec 2012 20:49:45 +0900
Subject: [PATCH] fix distance

---
 sprout/iterator/distance.hpp | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/sprout/iterator/distance.hpp b/sprout/iterator/distance.hpp
index 1187be1c..4a9db58e 100644
--- a/sprout/iterator/distance.hpp
+++ b/sprout/iterator/distance.hpp
@@ -68,11 +68,22 @@ namespace sprout {
 		}
 
 		template<typename InputIterator>
-		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
+		inline SPROUT_CONSTEXPR typename std::enable_if<
+			std::is_literal_type<InputIterator>::value,
+			typename std::iterator_traits<InputIterator>::difference_type
+		>::type
 		iterator_distance(InputIterator first, InputIterator last) {
 			typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
 			return sprout::iterator_detail::iterator_distance(first, last, category());
 		}
+		template<typename InputIterator>
+		inline SPROUT_CONSTEXPR typename std::enable_if<
+			!std::is_literal_type<InputIterator>::value,
+			typename std::iterator_traits<InputIterator>::difference_type
+		>::type
+		iterator_distance(InputIterator first, InputIterator last) {
+			return std::distance(first, last);
+		}
 	}	// namespace iterator_detail
 }	// namespace sprout
 
@@ -92,7 +103,8 @@ namespace sprout {
 	//
 	//	effect:
 	//		ADL callable iterator_distance(first, last) -> iterator_distance(first, last)
-	//		[first, last) is RandomAccessIterator && not Pointer -> last - first
+	//		otherwise, [first, last) is LiteralType -> std::distance(first, last)
+	//		otherwise, [first, last) is RandomAccessIterator && not Pointer -> last - first
 	//		otherwise -> linearly count: first to last
 	//
 	template<typename InputIterator>