/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.lang3.function;
import java.util.Objects;
import java.util.function.Function;
A functional interface like Function
that declares a Throwable
. Type parameters: Since: 3.11
/**
* A functional interface like {@link Function} that declares a {@code Throwable}.
*
* @param <T> Input type 1.
* @param <R> Return type.
* @param <E> Thrown exception.
* @since 3.11
*/
@FunctionalInterface
public interface FailableFunction<T, R, E extends Throwable> {
NOP singleton /** NOP singleton */
@SuppressWarnings("rawtypes")
FailableFunction NOP = t -> null;
Returns a function that always returns its input argument.
Type parameters: - <T> – the type of the input and output objects to the function
- <E> – Thrown exception.
Returns: a function that always returns its input argument
/**
* Returns a function that always returns its input argument.
*
* @param <T> the type of the input and output objects to the function
* @param <E> Thrown exception.
* @return a function that always returns its input argument
*/
static <T, E extends Throwable> FailableFunction<T, T, E> identity() {
return t -> t;
}
Returns The NOP singleton.
Type parameters: Returns: The NOP singleton.
/**
* 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;
}
Returns a composed FailableFunction
like Function.andThen(Function)
. Params: - after – the operation to perform after this one.
Type parameters: - <V> – the output type of the
after
function, and of the composed function.
Throws: - NullPointerException – when
after
is null.
Returns: a composed FailableFunction
like Function.andThen(Function)
.
/**
* Returns a composed {@code FailableFunction} like {@link Function#andThen(Function)}.
*
* @param <V> the output type of the {@code after} function, and of the composed function.
* @return a composed {@code FailableFunction} like {@link Function#andThen(Function)}.
* @param after the operation to perform after this one.
* @throws NullPointerException when {@code after} is null.
*/
default <V> FailableFunction<T, V, E> andThen(final FailableFunction<? super R, ? extends V, E> after) {
Objects.requireNonNull(after);
return (final T t) -> after.apply(apply(t));
}
Applies this function.
Params: - input – the input for the function
Throws: - E – Thrown when the function fails.
Returns: the result of the function
/**
* Applies this function.
*
* @param input the input for the function
* @return the result of the function
* @throws E Thrown when the function fails.
*/
R apply(T input) throws E;
Returns a composed FailableFunction
like Function.compose(Function)
. Params: - before – the operator to apply before this one.
Type parameters: - <V> – the input type to the
before
function, and to the composed function.
Throws: - NullPointerException – if before is null.
See Also: Returns: a a composed FailableFunction
like Function.compose(Function)
.
/**
* Returns a composed {@code FailableFunction} like {@link Function#compose(Function)}.
*
* @param <V> the input type to the {@code before} function, and to the composed function.
* @param before the operator to apply before this one.
* @return a a composed {@code FailableFunction} like {@link Function#compose(Function)}.
* @throws NullPointerException if before is null.
* @see #andThen(FailableFunction)
*/
default <V> FailableFunction<V, R, E> compose(final FailableFunction<? super V, ? extends T, E> before) {
Objects.requireNonNull(before);
return (final V v) -> apply(before.apply(v));
}
}