From 5fcb039ab433e4569755d3dce39043dd759ac9e9 Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Sun, 23 Dec 2012 17:59:00 +0900
Subject: [PATCH] fix recursion depth: distance add random::make_range

---
 sprout/iterator/distance.hpp | 43 +++++++++++++++++++++++++++-----
 sprout/random.hpp            |  1 +
 sprout/random/range.hpp      | 48 ++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 6 deletions(-)
 create mode 100644 sprout/random/range.hpp

diff --git a/sprout/iterator/distance.hpp b/sprout/iterator/distance.hpp
index bbb73118..1187be1c 100644
--- a/sprout/iterator/distance.hpp
+++ b/sprout/iterator/distance.hpp
@@ -5,6 +5,7 @@
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/iterator/next.hpp>
+#include <sprout/utility/pair.hpp>
 #include <sprout/adl/not_found.hpp>
 
 namespace sprout_adl {
@@ -22,18 +23,48 @@ namespace sprout {
 			return last - first;
 		}
 
-		// Copyright (C) 2011 RiSK (sscrisk)
 		template<typename InputIterator>
-		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
-		iterator_distance_impl(InputIterator first, InputIterator last) {
-			return first == last ? 0
-				: 1 + sprout::iterator_detail::iterator_distance_impl(sprout::next(first), last)
+		inline SPROUT_CONSTEXPR sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type>
+		iterator_distance_impl_1(
+			sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type> const& current,
+			InputIterator last, typename std::iterator_traits<InputIterator>::difference_type n
+			)
+		{
+			typedef sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type> type;
+			return current.first == last ? current
+				: n == 1 ? type(sprout::next(current.first), current.second + 1)
+				: sprout::iterator_detail::iterator_distance_impl_1(
+					sprout::iterator_detail::iterator_distance_impl_1(
+						current,
+						last, n / 2
+						),
+					last, n - n / 2
+					)
+				;
+		}
+		template<typename InputIterator>
+		inline SPROUT_CONSTEXPR sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type>
+		iterator_distance_impl(
+			sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type> const& current,
+			InputIterator last, typename std::iterator_traits<InputIterator>::difference_type n
+			)
+		{
+			typedef sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type> type;
+			return current.first == last ? current
+				: sprout::iterator_detail::iterator_distance_impl(
+					sprout::iterator_detail::iterator_distance_impl_1(
+						current,
+						last, n
+						),
+					last, n * 2
+					)
 				;
 		}
 		template<typename InputIterator>
 		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
 		iterator_distance(InputIterator first, InputIterator last, void*) {
-			return sprout::iterator_detail::iterator_distance_impl(first, last);
+			typedef sprout::pair<InputIterator, typename std::iterator_traits<InputIterator>::difference_type> type;
+			return sprout::iterator_detail::iterator_distance_impl(type(first, 0), last, 1).second;
 		}
 
 		template<typename InputIterator>
diff --git a/sprout/random.hpp b/sprout/random.hpp
index b7cf38b7..a47897d7 100644
--- a/sprout/random.hpp
+++ b/sprout/random.hpp
@@ -7,6 +7,7 @@
 #include <sprout/random/variate_generator.hpp>
 #include <sprout/random/random_result.hpp>
 #include <sprout/random/iterator.hpp>
+#include <sprout/random/range.hpp>
 #include <sprout/random/unique_seed.hpp>
 
 #endif // #ifndef SPROUT_RANDOM_HPP
diff --git a/sprout/random/range.hpp b/sprout/random/range.hpp
new file mode 100644
index 00000000..e7a56ec5
--- /dev/null
+++ b/sprout/random/range.hpp
@@ -0,0 +1,48 @@
+#ifndef SPROUT_RANDOM_RANGE_HPP
+#define SPROUT_RANDOM_RANGE_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/iterator/generator_iterator.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+#include <sprout/range/range_container.hpp>
+#include <sprout/random/iterator.hpp>
+
+namespace sprout {
+	namespace random {
+		//
+		// make_range
+		//
+		template<
+			typename Engine, typename Distribution,
+			typename sprout::enabler_if<!std::is_integral<Distribution>::value>::type = sprout::enabler
+		>
+		inline SPROUT_CONSTEXPR auto
+		make_range(
+			Engine const& engine, Distribution const& distribution,
+			typename sprout::generator_iterator<typename std::remove_reference<decltype(distribution(engine))>::type>::difference_type count = -1
+			)
+		-> sprout::range::range_container<sprout::generator_iterator<typename std::remove_reference<decltype(distribution(engine))>::type> >
+		{
+			return sprout::range::range_container<sprout::generator_iterator<typename std::remove_reference<decltype(distribution(engine))>::type> >(
+				sprout::random::begin(engine, distribution, count),
+				sprout::random::end(engine, distribution)
+				);
+		}
+		template<typename Engine>
+		inline SPROUT_CONSTEXPR auto
+		make_range(
+			Engine const& engine,
+			typename sprout::generator_iterator<typename std::remove_reference<decltype(engine())>::type>::difference_type count = -1
+			)
+		-> sprout::range::range_container<sprout::generator_iterator<typename std::remove_reference<decltype(distribution(engine))>::type> >
+		{
+			return sprout::range::range_container<sprout::generator_iterator<typename std::remove_reference<decltype(distribution(engine))>::type> >(
+				sprout::random::begin(engine, count),
+				sprout::random::end(engine)
+				);
+		}
+	}	// namespace random
+}	// namespace sprout
+
+#endif // #ifndef SPROUT_RANDOM_RANGE_HPP