From 8e49cc6f8f2186ef028bfa765fd06e52ce5218c5 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sun, 15 Feb 2015 20:31:07 +0100
Subject: Reduced `Filter` and `Remove` implementations to direct aliases *
 i.e. instead of defining full class templates in the `detail` namespace we
 only define predicate helpers * I don't like how some symbols have to be
 prefixed with `tav::` in the `detail` namespace to prevent conflicts - this
 is one reason why as much implementation as possible should be moved to
 template aliases

---
 src/list/operation/higher/filter.h | 36 ++++++++++++++++--------------------
 src/list/operation/higher/remove.h | 21 ++++++++-------------
 2 files changed, 24 insertions(+), 33 deletions(-)

diff --git a/src/list/operation/higher/filter.h b/src/list/operation/higher/filter.h
index 17d49c2..9dcdf37 100644
--- a/src/list/operation/higher/filter.h
+++ b/src/list/operation/higher/filter.h
@@ -8,25 +8,17 @@ namespace tav {
 
 namespace detail {
 
-template <
-	template<typename> class Predicate,
-	typename                 List
->
-class Filter {
-	private:
-		template <
-			typename Current,
-			typename Previous
-		>
-		using predicate_wrapper = If<
-			Eval<Predicate<Current>>,
-			Cons<Current, Previous>,
-			Previous
-		>;
-
-	public:
-		typedef tav::Fold<predicate_wrapper, void, List> type;
-
+template <template<typename> class Predicate>
+struct filter_predicate {
+	template <
+		typename Current,
+		typename Previous
+	>
+	using function = If<
+		Eval<Predicate<Current>>,
+		Cons<Current, Previous>,
+		Previous
+	>;
 };
 
 }
@@ -35,7 +27,11 @@ template <
 	template<typename> class Predicate,
 	typename                 List
 >
-using Filter = Eval<detail::Filter<Predicate, List>>;
+using Filter = Fold<
+	detail::filter_predicate<Predicate>::template function,
+	void,
+	List
+>;
 
 }
 
diff --git a/src/list/operation/higher/remove.h b/src/list/operation/higher/remove.h
index e67e962..598f5a6 100644
--- a/src/list/operation/higher/remove.h
+++ b/src/list/operation/higher/remove.h
@@ -7,18 +7,10 @@ namespace tav {
 
 namespace detail {
 
-template <
-	template<typename> class Predicate,
-	typename                 List
->
-class Remove {
-	private:
-		template <typename Element>
-		using predicate_negator = Not<Predicate<Element>>;
-
-	public:
-		typedef tav::Filter<predicate_negator, List> type;
-
+template <template<typename> class Predicate>
+struct predicate_negator {
+	template <typename Element>
+	using function = Not<Predicate<Element>>;
 };
 
 }
@@ -27,7 +19,10 @@ template <
 	template<typename> class Predicate,
 	typename                 List
 >
-using Remove = Eval<detail::Remove<Predicate, List>>;
+using Remove = Filter<
+	detail::predicate_negator<Predicate>::template function,
+	List
+>;
 
 }
 
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