From 9bb66d9c1d8a7bf5bf02f5a7c400894e928d2a95 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Wed, 18 Feb 2015 22:37:39 +0100
Subject: Changed `ListIndex` to return false if no index is found *
 analogously to `list-index` and `find` in SRFI-1

---
 src/list/operation/higher/drop_while.h | 2 +-
 src/list/operation/higher/list_index.h | 2 +-
 src/list/operation/higher/take_while.h | 2 +-
 src/type.h                             | 6 ++++++
 4 files changed, 9 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/list/operation/higher/drop_while.h b/src/list/operation/higher/drop_while.h
index 1207020..8d013f9 100644
--- a/src/list/operation/higher/drop_while.h
+++ b/src/list/operation/higher/drop_while.h
@@ -13,7 +13,7 @@ template <
 >
 using DropWhile = Drop<
 	typename utility::predicate_assurance<
-		utility::predicate_negator<std::is_void>::template function,
+		IsSize,
 		Length<List>
 	>::template assure<
 		ListIndex<
diff --git a/src/list/operation/higher/list_index.h b/src/list/operation/higher/list_index.h
index bbf43ee..d665b82 100644
--- a/src/list/operation/higher/list_index.h
+++ b/src/list/operation/higher/list_index.h
@@ -29,7 +29,7 @@ template <
 	typename                 Index
 >
 struct index_of_first<Predicate, void, Index> {
-	typedef void type;
+	typedef Boolean<false> type;
 };
 
 }
diff --git a/src/list/operation/higher/take_while.h b/src/list/operation/higher/take_while.h
index f9fc3aa..105e83c 100644
--- a/src/list/operation/higher/take_while.h
+++ b/src/list/operation/higher/take_while.h
@@ -13,7 +13,7 @@ template <
 >
 using TakeWhile = Take<
 	typename utility::predicate_assurance<
-		utility::predicate_negator<std::is_void>::template function,
+		IsSize,
 		Length<List>
 	>::template assure<
 		ListIndex<
diff --git a/src/type.h b/src/type.h
index 508e22f..c2ad2d8 100644
--- a/src/type.h
+++ b/src/type.h
@@ -38,6 +38,12 @@ using IsEqualValue = Boolean<X::value == Y::value>;
 template <typename X>
 using IsTrue = IsEqualValue<X, Boolean<true>>;
 
+template <typename X>
+using IsBoolean = Eval<std::is_same<typename X::value_type, bool>>;
+
+template <typename X>
+using IsSize = Eval<std::is_same<typename X::value_type, std::size_t>>;
+
 }
 
 #endif  // TYPEASVALUE_SRC_TYPE_H_
-- 
cgit v1.2.3