IOFunction.java
/*
* 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.io.function;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
/**
* Like {@link Function} but throws {@link IOException}.
*
* @param <T> the type of the input to the operations.
* @param <R> the return type of the operations.
* @since 2.7
*/
@FunctionalInterface
public interface IOFunction<T, R> {
/**
* Returns a {@link IOFunction} that always returns its input argument.
*
* @param <T> the type of the input and output objects to the function
* @return a function that always returns its input argument
*/
@SuppressWarnings("unchecked")
static <T> IOFunction<T, T> identity() {
return Constants.IO_FUNCTION_ID;
}
/**
* Returns a composed {@link IOFunction} that first applies this function to its input, and then applies the
* {@code after} consumer to the result. If evaluation of either function throws an exception, it is relayed to the
* caller of the composed function.
*
* @param after the consumer to apply after this function is applied
* @return a composed function that first applies this function and then applies the {@code after} consumer
* @throws NullPointerException if after is null
*
* @see #compose(IOFunction)
*/
default IOConsumer<T> andThen(final Consumer<? super R> after) {
Objects.requireNonNull(after, "after");
return (final T t) -> after.accept(apply(t));
}
/**
* Returns a composed {@link IOFunction} that first applies this function to its input, and then applies the
* {@code after} function to the result. If evaluation of either function throws an exception, it is relayed to the
* caller of the composed function.
*
* @param <V> the type of output of the {@code after} function, and of the composed function
* @param after the function to apply after this function is applied
* @return a composed function that first applies this function and then applies the {@code after} function
* @throws NullPointerException if after is null
*
* @see #compose(IOFunction)
*/
default <V> IOFunction<T, V> andThen(final Function<? super R, ? extends V> after) {
Objects.requireNonNull(after, "after");
return (final T t) -> after.apply(apply(t));
}
/**
* Returns a composed {@link IOFunction} that first applies this function to its input, and then applies the
* {@code after} consumer to the result. If evaluation of either function throws an exception, it is relayed to the
* caller of the composed function.
*
* @param after the consumer to apply after this function is applied
* @return a composed function that first applies this function and then applies the {@code after} consumer
* @throws NullPointerException if after is null
*
* @see #compose(IOFunction)
*/
default IOConsumer<T> andThen(final IOConsumer<? super R> after) {
Objects.requireNonNull(after, "after");
return (final T t) -> after.accept(apply(t));
}
/**
* Returns a composed {@link IOFunction} that first applies this function to its input, and then applies the
* {@code after} function to the result. If evaluation of either function throws an exception, it is relayed to the
* caller of the composed function.
*
* @param <V> the type of output of the {@code after} function, and of the composed function
* @param after the function to apply after this function is applied
* @return a composed function that first applies this function and then applies the {@code after} function
* @throws NullPointerException if after is null
*
* @see #compose(IOFunction)
*/
default <V> IOFunction<T, V> andThen(final IOFunction<? super R, ? extends V> after) {
Objects.requireNonNull(after, "after");
return (final T t) -> after.apply(apply(t));
}
/**
* Applies this function to the given argument.
*
* @param t the function argument
* @return the function result
* @throws IOException if an I/O error occurs.
*/
R apply(final T t) throws IOException;
/**
* Creates a {@link Function} for this instance that throws {@link UncheckedIOException} instead of {@link IOException}.
*
* @return an UncheckedIOException Function.
* @since 2.12.0
*/
default Function<T, R> asFunction() {
return t -> Uncheck.apply(this, t);
}
/**
* Returns a composed {@link IOFunction} that first applies the {@code before} function to its input, and then applies
* this function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the
* composed function.
*
* @param <V> the type of input to the {@code before} function, and to the composed function
* @param before the function to apply before this function is applied
* @return a composed function that first applies the {@code before} function and then applies this function
* @throws NullPointerException if before is null
*
* @see #andThen(IOFunction)
*/
default <V> IOFunction<V, R> compose(final Function<? super V, ? extends T> before) {
Objects.requireNonNull(before, "before");
return (final V v) -> apply(before.apply(v));
}
/**
* Returns a composed {@link IOFunction} that first applies the {@code before} function to its input, and then applies
* this function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the
* composed function.
*
* @param <V> the type of input to the {@code before} function, and to the composed function
* @param before the function to apply before this function is applied
* @return a composed function that first applies the {@code before} function and then applies this function
* @throws NullPointerException if before is null
*
* @see #andThen(IOFunction)
*/
default <V> IOFunction<V, R> compose(final IOFunction<? super V, ? extends T> before) {
Objects.requireNonNull(before, "before");
return (final V v) -> apply(before.apply(v));
}
/**
* Returns a composed {@link IOFunction} that first applies the {@code before} function to its input, and then applies
* this function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the
* composed function.
*
* @param before the supplier which feeds the application of this function
* @return a composed function that first applies the {@code before} function and then applies this function
* @throws NullPointerException if before is null
*
* @see #andThen(IOFunction)
*/
default IOSupplier<R> compose(final IOSupplier<? extends T> before) {
Objects.requireNonNull(before, "before");
return () -> apply(before.get());
}
/**
* Returns a composed {@link IOFunction} that first applies the {@code before} function to its input, and then applies
* this function to the result. If evaluation of either function throws an exception, it is relayed to the caller of the
* composed function.
*
* @param before the supplier which feeds the application of this function
* @return a composed function that first applies the {@code before} function and then applies this function
* @throws NullPointerException if before is null
*
* @see #andThen(IOFunction)
*/
default IOSupplier<R> compose(final Supplier<? extends T> before) {
Objects.requireNonNull(before, "before");
return () -> apply(before.get());
}
}