From fce61f0defdef39d7139b2d714d5caed42c06c9b Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Thu, 20 Dec 2012 00:09:05 +0900
Subject: [PATCH] add static_variant_visitor

---
 sprout/variant.hpp                        |  2 ++
 sprout/variant/apply_visitor.hpp          | 34 +-----------------
 sprout/variant/static_variant_visitor.hpp | 22 ++++++++++++
 sprout/variant/static_visitor.hpp         |  3 ++
 sprout/variant/variant.hpp                | 42 ++++++++++++++++++-----
 sprout/variant/visitor_result.hpp         | 41 ++++++++++++++++++++++
 6 files changed, 103 insertions(+), 41 deletions(-)
 create mode 100644 sprout/variant/static_variant_visitor.hpp
 create mode 100644 sprout/variant/visitor_result.hpp

diff --git a/sprout/variant.hpp b/sprout/variant.hpp
index d95fb9b7..5ef1f8dc 100644
--- a/sprout/variant.hpp
+++ b/sprout/variant.hpp
@@ -7,6 +7,8 @@
 #include <sprout/variant/tuple.hpp>
 #include <sprout/variant/get.hpp>
 #include <sprout/variant/static_visitor.hpp>
+#include <sprout/variant/static_variant_visitor.hpp>
+#include <sprout/variant/visitor_result.hpp>
 #include <sprout/variant/apply_visitor.hpp>
 
 #endif	// #ifndef SPROUT_VARIANT_HPP
diff --git a/sprout/variant/apply_visitor.hpp b/sprout/variant/apply_visitor.hpp
index 205a5ed7..99e26cbb 100644
--- a/sprout/variant/apply_visitor.hpp
+++ b/sprout/variant/apply_visitor.hpp
@@ -4,41 +4,9 @@
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/utility/forward.hpp>
-#include <sprout/type_traits/has_xxx.hpp>
+#include <sprout/variant/visitor_result.hpp>
 
 namespace sprout {
-	//
-	// has_visitor_result
-	//
-	SPROUT_HAS_XXX_TEMPLATE_DEF_LAZY(visitor_result);
-
-	namespace detail {
-		template<typename Visitor, typename Visitable, typename = void>
-		struct visitor_result_impl;
-		template<typename Visitor, typename Visitable>
-		struct visitor_result_impl<
-			Visitor, Visitable,
-			typename std::enable_if<sprout::has_visitor_result<Visitable>::value>::type
-		>
-			: public Visitable::template visitor_result<Visitor, Visitable>
-		{};
-		template<typename Visitor, typename Visitable>
-		struct visitor_result_impl<
-			Visitor, Visitable,
-			typename std::enable_if<!sprout::has_visitor_result<Visitable>::value>::type
-		> {
-		public:
-			typedef typename Visitor::result_type type;
-		};
-	}	// namespace detail
-	//
-	// visitor_result
-	//
-	template<typename Visitor, typename Visitable>
-	struct visitor_result
-		: public sprout::detail::visitor_result_impl<Visitor, Visitable>
-	{};
-
 	//
 	// apply_visitor
 	//
diff --git a/sprout/variant/static_variant_visitor.hpp b/sprout/variant/static_variant_visitor.hpp
new file mode 100644
index 00000000..44bbf61b
--- /dev/null
+++ b/sprout/variant/static_variant_visitor.hpp
@@ -0,0 +1,22 @@
+#ifndef SPROUT_VARIANT_STATIC_VARIANT_VISITOR_HPP
+#define SPROUT_VARIANT_STATIC_VARIANT_VISITOR_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/variant/variant.hpp>
+
+namespace sprout {
+	//
+	// static_variant_visitor
+	//
+	class static_variant_visitor {
+	public:
+		template<typename... Types>
+		struct visitor_result {
+		public:
+			typedef sprout::variant<typename std::decay<Types>::type...> type;
+		};
+	};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_VARIANT_STATIC_VARIANT_VISITOR_HPP
diff --git a/sprout/variant/static_visitor.hpp b/sprout/variant/static_visitor.hpp
index 265c13cf..e7bd40e9 100644
--- a/sprout/variant/static_visitor.hpp
+++ b/sprout/variant/static_visitor.hpp
@@ -4,6 +4,9 @@
 #include <sprout/config.hpp>
 
 namespace sprout {
+	//
+	// static_visitor
+	//
 	template<typename R = void>
 	class static_visitor {
 	public:
diff --git a/sprout/variant/variant.hpp b/sprout/variant/variant.hpp
index 1ce6c193..5a62bf7c 100644
--- a/sprout/variant/variant.hpp
+++ b/sprout/variant/variant.hpp
@@ -16,6 +16,7 @@
 #include <sprout/type/algorithm/find_index.hpp>
 #include <sprout/functional/type_traits/has_type.hpp>
 #include <sprout/functional/type_traits/weak_result_type.hpp>
+#include <sprout/variant/visitor_result.hpp>
 
 namespace sprout {
 	template<typename... Types>
@@ -75,6 +76,15 @@ namespace sprout {
 	public:
 		typedef typename impl_type::tuple_type tuple_type;
 	private:
+		template<typename Visitor, typename Tuple, typename IndexTuple>
+		struct visitor_result_impl_2;
+		template<typename Visitor, typename Tuple, sprout::index_t... Indexes>
+		struct visitor_result_impl_2<Visitor, Tuple, sprout::index_tuple<Indexes...> > {
+		public:
+			typedef typename Visitor::template visitor_result<
+				decltype((std::declval<Visitor>())(sprout::tuples::get<Indexes>(std::declval<Tuple>())))...
+			>::type type;
+		};
 		template<typename Visitor, typename Tuple, typename IndexTuple>
 		struct visitor_result_impl_1;
 		template<typename Visitor, typename Tuple, sprout::index_t... Indexes>
@@ -91,19 +101,35 @@ namespace sprout {
 		template<typename Visitor, typename Tuple>
 		struct visitor_result_impl<
 			Visitor, Tuple,
-			typename std::enable_if<!sprout::has_result_type<sprout::weak_result_type<Visitor> >::value>::type
-		>
-			: public visitor_result_impl_1<Visitor, Tuple, typename sprout::index_range<0, sprout::tuples::tuple_size<Tuple>::value>::type>
-		{};
-		template<typename Visitor, typename Tuple>
-		struct visitor_result_impl<
-			Visitor, Tuple,
-			typename std::enable_if<sprout::has_result_type<sprout::weak_result_type<Visitor> >::value>::type
+			typename std::enable_if<
+				sprout::has_result_type<sprout::weak_result_type<Visitor> >::value
+			>::type
 		> {
 		public:
 			typedef typename sprout::weak_result_type<Visitor>::result_type type;
 		};
+		template<typename Visitor, typename Tuple>
+		struct visitor_result_impl<
+			Visitor, Tuple,
+			typename std::enable_if<
+				sprout::has_visitor_result<Visitor>::value
+					&& !sprout::has_result_type<sprout::weak_result_type<Visitor> >::value
+			>::type
+		>
+			: public visitor_result_impl_2<Visitor, Tuple, typename sprout::index_range<0, sprout::tuples::tuple_size<Tuple>::value>::type>
+		{};
+		template<typename Visitor, typename Tuple>
+		struct visitor_result_impl<
+			Visitor, Tuple,
+			typename std::enable_if<
+				!sprout::has_visitor_result<Visitor>::value
+					&& !sprout::has_result_type<sprout::weak_result_type<Visitor> >::value
+			>::type
+		>
+			: public visitor_result_impl_1<Visitor, Tuple, typename sprout::index_range<0, sprout::tuples::tuple_size<Tuple>::value>::type>
+		{};
 	public:
+		// visitation support
 		template<typename Visitor, typename Visitable>
 		struct visitor_result
 			: public visitor_result_impl<Visitor, typename Visitable::tuple_type>
diff --git a/sprout/variant/visitor_result.hpp b/sprout/variant/visitor_result.hpp
new file mode 100644
index 00000000..3fcc1836
--- /dev/null
+++ b/sprout/variant/visitor_result.hpp
@@ -0,0 +1,41 @@
+#ifndef SPROUT_VARIANT_VISITOR_RESULT_HPP
+#define SPROUT_VARIANT_VISITOR_RESULT_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/type_traits/has_xxx.hpp>
+
+namespace sprout {
+	//
+	// has_visitor_result
+	//
+	SPROUT_HAS_XXX_TEMPLATE_DEF_LAZY(visitor_result);
+
+	namespace detail {
+		template<typename Visitor, typename Visitable, typename = void>
+		struct visitor_result_impl;
+		template<typename Visitor, typename Visitable>
+		struct visitor_result_impl<
+			Visitor, Visitable,
+			typename std::enable_if<sprout::has_visitor_result<Visitable>::value>::type
+		>
+			: public Visitable::template visitor_result<Visitor, Visitable>
+		{};
+		template<typename Visitor, typename Visitable>
+		struct visitor_result_impl<
+			Visitor, Visitable,
+			typename std::enable_if<!sprout::has_visitor_result<Visitable>::value>::type
+		> {
+		public:
+			typedef typename Visitor::result_type type;
+		};
+	}	// namespace detail
+	//
+	// visitor_result
+	//
+	template<typename Visitor, typename Visitable>
+	struct visitor_result
+		: public sprout::detail::visitor_result_impl<Visitor, Visitable>
+	{};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_VARIANT_VISITOR_RESULT_HPP