From a7def70996e7172cb6e5d01134d38fa2e479ecd7 Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Thu, 11 Jul 2013 03:05:49 +0900
Subject: [PATCH] add types::upper_bound_index meta-function

---
 sprout/type/algorithm.hpp                   |  1 +
 sprout/type/algorithm/lower_bound_index.hpp | 48 +++++++++++-----
 sprout/type/algorithm/upper_bound_index.hpp | 61 +++++++++++++++++++++
 3 files changed, 96 insertions(+), 14 deletions(-)
 create mode 100644 sprout/type/algorithm/upper_bound_index.hpp

diff --git a/sprout/type/algorithm.hpp b/sprout/type/algorithm.hpp
index 32f0390d..55298a9f 100644
--- a/sprout/type/algorithm.hpp
+++ b/sprout/type/algorithm.hpp
@@ -5,5 +5,6 @@
 #include <sprout/type/algorithm/find_index.hpp>
 #include <sprout/type/algorithm/find_index_if.hpp>
 #include <sprout/type/algorithm/lower_bound_index.hpp>
+#include <sprout/type/algorithm/upper_bound_index.hpp>
 
 #endif	// #ifndef SPROUT_TYPE_ALGORITHM_HPP
diff --git a/sprout/type/algorithm/lower_bound_index.hpp b/sprout/type/algorithm/lower_bound_index.hpp
index 0f21056d..2f915a03 100644
--- a/sprout/type/algorithm/lower_bound_index.hpp
+++ b/sprout/type/algorithm/lower_bound_index.hpp
@@ -10,30 +10,50 @@
 namespace sprout {
 	namespace types {
 		namespace detail {
-			template<std::size_t I, typename Tuple, typename T, typename Compare, typename = void>
-			struct lower_bound_index_impl
-				: public std::integral_constant<std::size_t, I>
-			{};
-			template<std::size_t I, typename Tuple, typename T, typename Compare>
-			struct lower_bound_index_impl<
-				I, Tuple, T, Compare,
-				typename std::enable_if<(I < sprout::tuples::tuple_size<Tuple>::value)>::type
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last,
+				std::size_t Distance = (Last - First)
 			>
+			struct lower_bound_index_impl;
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last
+			>
+			struct lower_bound_index_impl<
+				Tuple, T, Compare, First, Last,
+				0
+			>
+				: public std::integral_constant<std::size_t, Last>
+			{};
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last
+			>
+			struct lower_bound_index_impl<
+				Tuple, T, Compare, First, Last,
+				1
+			>
+				: public std::integral_constant<
+					std::size_t,
+					Compare::template apply<typename sprout::types::tuple_element<First, Tuple>::type, T>::type::value ? Last : First
+				>
+			{};
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last,
+				std::size_t Distance
+			>
+			struct lower_bound_index_impl
 				: public std::conditional<
-					Compare::template apply<typename sprout::tuples::tuple_element<I, Tuple>::type, T>::type::value,
-					sprout::types::detail::lower_bound_index_impl<I + 1, Tuple, T, Compare>,
-					std::integral_constant<std::size_t, I>
+					Compare::template apply<typename sprout::types::tuple_element<First + Distance / 2, Tuple>::type, T>::type::value,
+					sprout::types::detail::lower_bound_index_impl<Tuple, T, Compare, First + Distance / 2, Last>,
+					sprout::types::detail::lower_bound_index_impl<Tuple, T, Compare, First, First + Distance / 2>
 				>::type
 			{};
 		}	// namespace detail
 		//
 		// lower_bound_index
 		//
-		//	TODO: O(log N) implementation
-		//
 		template<typename Tuple, typename T, typename Compare = sprout::types::less_>
 		struct lower_bound_index
-			: public sprout::types::detail::lower_bound_index_impl<0, Tuple, T, Compare>
+			: public sprout::types::detail::lower_bound_index_impl<Tuple, T, Compare, 0, sprout::types::tuple_size<Tuple>::value>
 		{};
 	}	// namespace types
 }	// namespace sprout
diff --git a/sprout/type/algorithm/upper_bound_index.hpp b/sprout/type/algorithm/upper_bound_index.hpp
new file mode 100644
index 00000000..f77e0053
--- /dev/null
+++ b/sprout/type/algorithm/upper_bound_index.hpp
@@ -0,0 +1,61 @@
+#ifndef SPROUT_TYPE_ALGORITHM_UPPER_BOUND_INDEX_HPP
+#define SPROUT_TYPE_ALGORITHM_UPPER_BOUND_INDEX_HPP
+
+#include <cstddef>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/type/functional/less.hpp>
+#include <sprout/type/tuple.hpp>
+
+namespace sprout {
+	namespace types {
+		namespace detail {
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last,
+				std::size_t Distance = (Last - First)
+			>
+			struct upper_bound_index_impl;
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last
+			>
+			struct upper_bound_index_impl<
+				Tuple, T, Compare, First, Last,
+				0
+			>
+				: public std::integral_constant<std::size_t, Last>
+			{};
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last
+			>
+			struct upper_bound_index_impl<
+				Tuple, T, Compare, First, Last,
+				1
+			>
+				: public std::integral_constant<
+					std::size_t,
+					!Compare::template apply<T, typename sprout::types::tuple_element<First, Tuple>::type>::type::value ? Last : First
+				>
+			{};
+			template<
+				typename Tuple, typename T, typename Compare, std::size_t First, std::size_t Last,
+				std::size_t Distance
+			>
+			struct upper_bound_index_impl
+				: public std::conditional<
+					!Compare::template apply<T, typename sprout::types::tuple_element<First + Distance / 2, Tuple>::type>::type::value,
+					sprout::types::detail::upper_bound_index_impl<Tuple, T, Compare, First + Distance / 2, Last>,
+					sprout::types::detail::upper_bound_index_impl<Tuple, T, Compare, First, First + Distance / 2>
+				>::type
+			{};
+		}	// namespace detail
+		//
+		// upper_bound_index
+		//
+		template<typename Tuple, typename T, typename Compare = sprout::types::less_>
+		struct upper_bound_index
+			: public sprout::types::detail::upper_bound_index_impl<Tuple, T, Compare, 0, sprout::types::tuple_size<Tuple>::value>
+		{};
+	}	// namespace types
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_TYPE_ALGORITHM_UPPER_BOUND_INDEX_HPP