[LANG-1568]

org.apache.commons.lang3.function.FailableBiFunction.andThen(FailableFunction<?
super R, ? extends V, E>)

3 files changed, 52 insertions, 3 deletions

diff --git a/src/main/java/org/apache/commons/lang3/function/FailableBiConsumer.java b/src/main/java/org/apache/commons/lang3/function/FailableBiConsumer.java
index 5f56b06e9..6d5d99f5f 100644
--- a/src/main/java/org/apache/commons/lang3/function/FailableBiConsumer.java
+++ b/src/main/java/org/apache/commons/lang3/function/FailableBiConsumer.java
@@ -37,7 +37,7 @@ public interface FailableBiConsumer<T, U, E extends Throwable> {
 
     /**
      * Returns The NOP singleton.
-     * 
+     *
      * @param <T> Consumed type 1.
      * @param <U> Consumed type 2.
      * @param <E> Thrown exception.
@@ -62,9 +62,9 @@ public interface FailableBiConsumer<T, U, E extends Throwable> {
      * @param after the operation to perform after this one.
      * @return a composed {@code FailableBiConsumer} like {@link BiConsumer#andThen(BiConsumer)}.
      * @throws E Thrown when a consumer fails.
-     * @throws NullPointerException if {@code after} is null
+     * @throws NullPointerException if {@code after} is null.
      */
-    default FailableBiConsumer<T, U, E> andThen(FailableBiConsumer<? super T, ? super U, E> after) throws E {
+    default FailableBiConsumer<T, U, E> andThen(final FailableBiConsumer<? super T, ? super U, E> after) throws E {
         Objects.requireNonNull(after);
 
         return (t, u) -> {
diff --git a/src/main/java/org/apache/commons/lang3/function/FailableBiFunction.java b/src/main/java/org/apache/commons/lang3/function/FailableBiFunction.java
index d112be8e9..be0e4704b 100644
--- a/src/main/java/org/apache/commons/lang3/function/FailableBiFunction.java
+++ b/src/main/java/org/apache/commons/lang3/function/FailableBiFunction.java
@@ -17,7 +17,9 @@
 
 package org.apache.commons.lang3.function;
 
+import java.util.Objects;
 import java.util.function.BiFunction;
+import java.util.function.Function;
 
 /**
  * A functional interface like {@link BiFunction} that declares a {@code Throwable}.
@@ -31,6 +33,37 @@ import java.util.function.BiFunction;
 @FunctionalInterface
 public interface FailableBiFunction<T, U, R, E extends Throwable> {
 
+    /** NOP singleton */
+    @SuppressWarnings("rawtypes")
+    final FailableBiFunction NOP = (t, u) -> null;
+
+    /**
+     * Returns The NOP singleton.
+     *
+     * @param <T> Consumed type 1.
+     * @param <U> Consumed type 2.
+     * @param <R> Return type.
+     * @param <E> Thrown exception.
+     * @return The NOP singleton.
+     */
+    static <T, U, R, E extends Throwable> FailableBiFunction<T, U, R, E> nop() {
+        return NOP;
+    }
+
+    /**
+     * Returns a composed {@code FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
+     *
+     * @param <V> the type of output of the {@code after} function, and of the composed function
+     * @param after the operation to perform after this one.
+     * @return a composed {@code FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
+     * @throws E Thrown when a consumer fails.
+     * @throws NullPointerException if after is null.
+     */
+    default <V> FailableBiFunction<T, U, V, E> andThen(final FailableFunction<? super R, ? extends V, E> after) throws E {
+        Objects.requireNonNull(after);
+        return (final T t, final U u) -> after.apply(apply(t, u));
+    }
+
     /**
      * Applies this function.
      *
diff --git a/src/main/java/org/apache/commons/lang3/function/FailableFunction.java b/src/main/java/org/apache/commons/lang3/function/FailableFunction.java
index 7de443796..3d4b905b6 100644
--- a/src/main/java/org/apache/commons/lang3/function/FailableFunction.java
+++ b/src/main/java/org/apache/commons/lang3/function/FailableFunction.java
@@ -30,6 +30,22 @@ import java.util.function.Function;
 @FunctionalInterface
 public interface FailableFunction<T, R, E extends Throwable> {
 
+    /** NOP singleton */
+    @SuppressWarnings("rawtypes")
+    final FailableFunction NOP = t -> null;
+
+    /**
+     * Returns The NOP singleton.
+     *
+     * @param <T> Consumed type 1.
+     * @param <R> Return type.
+     * @param <E> Thrown exception.
+     * @return The NOP singleton.
+     */
+    static <T, R, E extends Throwable> FailableFunction<T, R, E> nop() {
+        return NOP;
+    }
+
     /**
      * Applies this function.
      *