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ThrowingFunction.java
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ThrowingFunction.java
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/*
* Copyright 2016 the original author or authors.
*
* Licensed 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 com.pivovarit.function;
import java.util.Optional;
import java.util.function.Function;
import static java.util.Objects.requireNonNull;
/**
* Represents a function that accepts one argument and returns a value;
* Function might throw a checked exception instance.
*
* @param <T> the type of the input to the function
* @param <R> the type of the result of the function
* @param <E> the type of the thrown checked exception
* @author Grzegorz Piwowarek
*/
@FunctionalInterface
public interface ThrowingFunction<T, R, E extends Exception> {
R apply(T arg) throws E;
/**
* @return a Function that returns the result of the given function as an Optional instance.
* In case of a failure, empty Optional is returned
*/
static <T, R> Function<T, Optional<R>> lifted(final ThrowingFunction<? super T, ? extends R, ?> function) {
requireNonNull(function);
return t -> {
try {
return Optional.ofNullable(function.apply(t));
} catch (final Exception e) {
return Optional.empty();
}
};
}
static <T, R> Function<T, R> unchecked(final ThrowingFunction<? super T, ? extends R, ?> function) {
requireNonNull(function);
return t -> {
try {
return function.apply(t);
} catch (final Exception e) {
throw new CheckedException(e);
}
};
}
static <T1, R> Function<T1, R> sneaky(ThrowingFunction<? super T1, ? extends R, ?> function) {
requireNonNull(function);
return t -> {
try {
return function.apply(t);
} catch (final Exception ex) {
return SneakyThrowUtil.sneakyThrow(ex);
}
};
}
default Function<T, Optional<R>> lift() {
return t -> {
try {
return Optional.ofNullable(apply(t));
} catch (final Exception e) {
return Optional.empty();
}
};
}
}