Added `TakeWhile` higher order list operation

* as its name implies this function returns the longest initial prefix of a list that satisfies a given _Predicate_
* added appropriate test case

1 files changed, 33 insertions, 0 deletions

diff --git a/src/list/operation/higher/take_while.h b/src/list/operation/higher/take_while.h
new file mode 100644
index 0000000..01062f4
--- /dev/null
+++ b/src/list/operation/higher/take_while.h
@@ -0,0 +1,33 @@
+#ifndef TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_TAKE_WHILE_H_
+#define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_TAKE_WHILE_H_
+
+#include "type.h"
+#include "conditional/if.h"
+
+namespace tav {
+
+template <
+	template<typename> class Predicate,
+	typename                 Current
+>
+struct TakeWhile {
+	typedef If<
+		Predicate<Head<Current>>::type::value,
+		Cons<
+			Head<Current>,
+			typename TakeWhile<Predicate, Tail<Current>>::type
+		>,
+		void
+	> type;
+};
+
+template <
+	template<typename> class Predicate
+>
+struct TakeWhile<Predicate, void> {
+	typedef void type;
+};
+
+}
+
+#endif  // TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_TAKE_WHILE_H_