1 files changed, 25 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/yolean/function/ThrowingFunction.java b/vespajlib/src/main/java/com/yahoo/yolean/function/ThrowingFunction.java
new file mode 100644
index 00000000000..6e459509b1d
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+++ b/vespajlib/src/main/java/com/yahoo/yolean/function/ThrowingFunction.java
@@ -0,0 +1,25 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.yolean.function;
+
+import java.util.Objects;
+
+/**
+ * Functional interface that mirrors the Function interface, but allows for an
+ * exception to be thrown.
+ *
+ * @author oyving
+ */
+@FunctionalInterface
+public interface ThrowingFunction<T, R, E extends Throwable> {
+    R apply(T input) throws E;
+
+    default <V> ThrowingFunction<T, V, E> andThen(ThrowingFunction<? super R, ? extends V, ? extends E> after) {
+        Objects.requireNonNull(after);
+        return (T t) -> after.apply(apply(t));
+    }
+
+    default <V> ThrowingFunction<V, R, E> compose(ThrowingFunction<? super V, ? extends T, ? extends E> before) {
+        Objects.requireNonNull(before);
+        return (V v) -> apply(before.apply(v));
+    }
+}