org.apache.commons.lang3.function.FailableFunction Maven / Gradle / Ivy
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* 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 {@link Function} that declares a {@code Throwable}.
*
* @param Input type 1.
* @param Return type.
* @param Thrown exception.
* @since 3.11
*/
@FunctionalInterface
public interface FailableFunction {
/** NOP singleton */
@SuppressWarnings("rawtypes")
FailableFunction NOP = t -> null;
/**
* Returns a function that always returns its input argument.
*
* @param the type of the input and output objects to the function
* @param Thrown exception.
* @return a function that always returns its input argument
*/
static FailableFunction identity() {
return t -> t;
}
/**
* Returns The NOP singleton.
*
* @param Consumed type 1.
* @param Return type.
* @param Thrown exception.
* @return The NOP singleton.
*/
static FailableFunction nop() {
return NOP;
}
/**
* Returns a composed {@code FailableFunction} like {@link Function#andThen(Function)}.
*
* @param 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 FailableFunction andThen(final FailableFunction after) {
Objects.requireNonNull(after);
return (final T t) -> after.apply(apply(t));
}
/**
* 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 {@code FailableFunction} like {@link Function#compose(Function)}.
*
* @param 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 FailableFunction compose(final FailableFunction before) {
Objects.requireNonNull(before);
return (final V v) -> apply(before.apply(v));
}
}