Move transform_traits into its own file

Author: davidstone

CMakeLists.txt

@@ -250,6 +250,7 @@ target_sources(containers PUBLIC
 		source/containers/algorithms/splice.cpp
 		source/containers/algorithms/transform.cpp
 		source/containers/algorithms/transform_iterator.cpp
+		source/containers/algorithms/transform_traits.cpp
 		source/containers/algorithms/uninitialized.cpp
 		source/containers/algorithms/unique.cpp
 		source/containers/algorithms/zip.cpp

source/containers/algorithms/transform.cpp

@@ -10,6 +10,7 @@ module;
 export module containers.algorithms.transform;
 
 import containers.algorithms.compare;
+import containers.algorithms.transform_traits;
 import containers.array;
 import containers.algorithms.transform_iterator;
 import containers.adapt;

source/containers/algorithms/transform_iterator.cpp

@@ -9,6 +9,7 @@ module;
 
 export module containers.algorithms.transform_iterator;
 
+import containers.algorithms.transform_traits;
 import containers.default_adapt_traits;
 import containers.is_iterator;
 import containers.iterator_adapter;
@@ -17,39 +18,6 @@ import std_module;
 
 namespace containers {
 
-export template<typename UnaryFunction>
-struct transform_traits : default_add, default_subtract, default_compare {
-private:
-	[[no_unique_address]] UnaryFunction m_dereference;
-
-public:
-	constexpr explicit transform_traits(UnaryFunction dereference_):
-		m_dereference(std::move(dereference_))
-	{
-	}
-	
-	constexpr auto dereference(iterator auto const & it) const OPERATORS_RETURNS(
-		std::invoke(m_dereference, *it)
-	)
-};
-
-export template<typename UnaryFunction>
-struct transform_traits_dereference : default_add, default_subtract, default_compare {
-private:
-	[[no_unique_address]] UnaryFunction m_dereference;
-
-public:
-	constexpr explicit transform_traits_dereference(UnaryFunction dereference_):
-		m_dereference(std::move(dereference_))
-	{
-	}
-	
-	constexpr auto dereference(iterator auto const & it) const OPERATORS_RETURNS(
-		std::invoke(m_dereference, it)
-	)
-
-};
-
 export constexpr auto transform_iterator(iterator auto it, auto dereference) {
 	return adapt_iterator(std::move(it), transform_traits(std::move(dereference)));
 }

source/containers/algorithms/transform_traits.cpp

@@ -0,0 +1,46 @@
+// Copyright David Stone 2018.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+export module containers.algorithms.transform_traits;
+
+import containers.default_adapt_traits;
+import containers.is_iterator;
+import containers.iter_reference_t;
+
+import std_module;
+
+namespace containers {
+
+export template<typename UnaryFunction>
+struct transform_traits : default_add, default_subtract, default_compare {
+	constexpr explicit transform_traits(UnaryFunction dereference_):
+		m_dereference(std::move(dereference_))
+	{
+	}
+	
+	template<iterator It> requires std::invocable<UnaryFunction const &, iter_reference_t<It>>
+	constexpr auto dereference(It const & it) const -> decltype(auto) {
+		return std::invoke(m_dereference, *it);
+	}
+private:
+	[[no_unique_address]] UnaryFunction m_dereference;
+};
+
+export template<typename UnaryFunction>
+struct transform_traits_dereference : default_add, default_subtract, default_compare {
+	constexpr explicit transform_traits_dereference(UnaryFunction dereference_):
+		m_dereference(std::move(dereference_))
+	{
+	}
+	
+	template<iterator It> requires std::invocable<UnaryFunction const &, It>
+	constexpr auto dereference(It const & it) const -> decltype(auto) {
+		return std::invoke(m_dereference, it);
+	}
+private:
+	[[no_unique_address]] UnaryFunction m_dereference;
+};
+
+} // namespace containers