1 files changed, 34 insertions, 0 deletions
diff --git a/src/utility/predicate.h b/src/utility/predicate.h
new file mode 100644
index 0000000..f06fcee
--- /dev/null
+++ b/src/utility/predicate.h
@@ -0,0 +1,34 @@
+#ifndef TYPEASVALUE_SRC_UTILITY_PREDICATE_H_
+#define TYPEASVALUE_SRC_UTILITY_PREDICATE_H_
+
+#include "conditional/if.h"
+#include "operation/logic.h"
+
+namespace tav {
+
+namespace utility {
+
+template <
+	template<typename> class Predicate,
+	typename                 Surrogate
+>
+struct predicate_assurance {
+	template <typename Value>
+	using assure = If<
+		Eval<Predicate<Value>>,
+		Value,
+		Surrogate
+	>;
+};
+
+template <template<typename> class Predicate>
+struct predicate_negator {
+	template <typename Element>
+	using function = Not<Predicate<Element>>;
+};
+
+}
+
+}
+
+#endif  // TYPEASVALUE_SRC_UTILITY_PREDICATE_H_