Moved `Apply`'s placeholder into separate detail header

* separate actual `Apply` specializations in `detail/apply.h` from placeholder details

2 files changed, 45 insertions, 29 deletions

diff --git a/src/function/detail/apply.h b/src/function/detail/apply.h
index aca0af4..2f4c782 100644
--- a/src/function/detail/apply.h
+++ b/src/function/detail/apply.h
@@ -1,38 +1,11 @@
 #ifndef TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_
 #define TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_
 
-#include <type_traits>
-
-#include "list/list.h"
-#include "list/operation/nth.h"
-#include "list/operation/higher/query.h"
+#include "placeholder.h"
 
 namespace tav {
-namespace detail {
-
-struct placeholder_tag { };
-
-template <typename Type>
-using is_placeholder = Eval<std::is_base_of<placeholder_tag, Type>>;
-
-template <int Index>
-struct placeholder : placeholder_tag { };
-
-template <typename, typename Argument>
-struct resolve_placeholder {
-	typedef Argument type;
-};
 
-template <
-	typename Partials,
-	int      Index
->
-struct resolve_placeholder<Partials, placeholder<Index>> {
-	typedef Nth<Size<Index>, Partials> type;
-};
-
-template <typename... Arguments>
-using count_placeholders = Count<is_placeholder, List<Arguments...>>;
+namespace detail {
 
 template <
 	template<typename...> class Function,
@@ -81,6 +54,7 @@ struct apply_pair : apply_variadic<Function, Arguments...> {
 };
 
 }
+
 }
 
 #endif  // TYPEASVALUE_SRC_FUNCTION_DETAIL_APPLY_H_
diff --git a/src/function/detail/placeholder.h b/src/function/detail/placeholder.h
new file mode 100644
index 0000000..8105de5
--- /dev/null
+++ b/src/function/detail/placeholder.h
@@ -0,0 +1,42 @@
+#ifndef TYPEASVALUE_SRC_FUNCTION_DETAIL_PLACEHOLDER_H_
+#define TYPEASVALUE_SRC_FUNCTION_DETAIL_PLACEHOLDER_H_
+
+#include <type_traits>
+
+#include "list/list.h"
+#include "list/operation/nth.h"
+#include "list/operation/higher/query.h"
+
+namespace tav {
+
+namespace detail {
+
+struct placeholder_tag { };
+
+template <int Index>
+struct placeholder : placeholder_tag { };
+
+template <typename Type>
+using is_placeholder = Eval<std::is_base_of<placeholder_tag, Type>>;
+
+template <typename... Arguments>
+using count_placeholders = Count<is_placeholder, List<Arguments...>>;
+
+template <typename, typename Argument>
+struct resolve_placeholder {
+	typedef Argument type;
+};
+
+template <
+	typename Partials,
+	int      Index
+>
+struct resolve_placeholder<Partials, placeholder<Index>> {
+	typedef Nth<Size<Index>, Partials> type;
+};
+
+}
+
+}
+
+#endif  // TYPEASVALUE_SRC_FUNCTION_DETAIL_PLACEHOLDER_H_