From a8bec66b05eece7b8a39102fb1b0ba8f778eb9fe Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Thu, 19 Feb 2015 13:45:07 +0100
Subject: Reimplemented `Find` in terms of `ListIndex` * `ListIndex` already
 implements the necessary partial template specializations for finding
 elements matching a predicate * reimplemented `Cond` using
 `detail::find_variadic` as `Find` depends on `Apply` which in turn depends on
 `Cond` ** it is useful if core functionality such as the branched conditional
 `Cond` do not require higher order functionality such as `Find` *** otherwise
 one can not use core functionality in the implementation of higher order
 functionality * introduced `utility::predicate_guard` helper template **
 checks a given value using a predicate and only forwards the value to the
 guarded function if this check is successful ** if check is unsuccessful it
 returns a surrogate value simmilar to `utility::predicate_assurance`

---
 src/list/operation/higher/find.h | 38 ++++++++++++--------------------------
 1 file changed, 12 insertions(+), 26 deletions(-)

(limited to 'src/list/operation/higher/find.h')

diff --git a/src/list/operation/higher/find.h b/src/list/operation/higher/find.h
index 48533b7..aeb0c2a 100644
--- a/src/list/operation/higher/find.h
+++ b/src/list/operation/higher/find.h
@@ -1,39 +1,25 @@
 #ifndef TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_FIND_H_
 #define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_FIND_H_
 
-#include "type.h"
-#include "conditional/if.h"
+#include "utility/predicate.h"
+#include "function/apply.h"
+#include "list/operation/nth.h"
+#include "list_index.h"
 
 namespace tav {
 
-namespace detail {
-
-template <
-	template<typename> class Predicate,
-	typename                 Current
->
-struct Find {
-	typedef If<
-		Eval<Predicate<Head<Current>>>,
-		Head<Current>,
-		Eval<Find<Predicate, Tail<Current>>>
-	> type;
-};
-
-template <
-	template<typename> class Predicate
->
-struct Find<Predicate, void> {
-	typedef Boolean<false> type;
-};
-
-}
-
 template <
 	template<typename> class Predicate,
 	typename                 List
 >
-using Find = Eval<detail::Find<Predicate, List>>;
+using Find = typename utility::predicate_guard<
+	IsSize,
+	Apply<Nth, _0, List>::template function,
+	Boolean<false>
+>::template check<
+	ListIndex<Predicate, List>
+>;
+
 
 }
 
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