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The Apache Commons IO library contains utility classes, stream implementations, file filters,
file comparators, endian transformation classes, and much more.
/*
* 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.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 the type of the input to the operations.
* @param the return type of the operations.
* @since 2.7
*/
@FunctionalInterface
public interface IOFunction {
/**
* Applies this function to the given argument.
*
* @param t the function argument
* @return the function result
*
* @throws IOException if the function throws an IOException
*/
R apply(final T t) throws IOException;
/**
* 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 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 IOFunction compose(final IOFunction before) {
Objects.requireNonNull(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 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 IOFunction compose(final Function before) {
Objects.requireNonNull(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 compose(final IOSupplier before) {
Objects.requireNonNull(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 compose(final Supplier before) {
Objects.requireNonNull(before);
return () -> apply(before.get());
}
/**
* 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 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 IOFunction andThen(final IOFunction after) {
Objects.requireNonNull(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} function to the result.
* If evaluation of either function throws an exception, it is relayed to
* the caller of the composed function.
*
* @param 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 IOFunction andThen(final Function after) {
Objects.requireNonNull(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 andThen(final IOConsumer after) {
Objects.requireNonNull(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} 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 andThen(final Consumer after) {
Objects.requireNonNull(after);
return (final T t) -> after.accept(apply(t));
}
/**
* Returns a {@link IOFunction} that always returns its input argument.
*
* @param the type of the input and output objects to the function
* @return a function that always returns its input argument
*/
static IOFunction identity() {
return t -> t;
}
}