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/*
* Copyright 2016-2024 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
*
* https://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.springframework.data.util;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Optional;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.springframework.util.Assert;
/**
* Utility methods to work with {@link Optional}s.
*
* @author Oliver Gierke
* @author Christoph Strobl
*/
public interface Optionals {
/**
* Returns whether any of the given {@link Optional}s is present.
*
* @param optionals must not be {@literal null}.
* @return
*/
static boolean isAnyPresent(Optional... optionals) {
Assert.notNull(optionals, "Optionals must not be null");
for (Optional optional : optionals) {
if (optional.isPresent()) {
return true;
}
}
return false;
}
/**
* Turns the given {@link Optional} into a one-element {@link Stream} or an empty one if not present.
*
* @param optionals must not be {@literal null}.
* @return
*/
@SafeVarargs
static Stream toStream(Optional... optionals) {
Assert.notNull(optionals, "Optional must not be null");
return Arrays.asList(optionals).stream().flatMap(it -> it.map(Stream::of).orElseGet(Stream::empty));
}
/**
* Applies the given function to the elements of the source and returns the first non-empty result.
*
* @param source must not be {@literal null}.
* @param function must not be {@literal null}.
* @return
*/
static Optional firstNonEmpty(Iterable source, Function> function) {
Assert.notNull(source, "Source must not be null");
Assert.notNull(function, "Function must not be null");
return Streamable.of(source).stream()//
.map(function::apply)//
.filter(Optional::isPresent)//
.findFirst().orElseGet(Optional::empty);
}
/**
* Applies the given function to the elements of the source and returns the first non-empty result.
*
* @param source must not be {@literal null}.
* @param function must not be {@literal null}.
* @return
*/
static T firstNonEmpty(Iterable source, Function function, T defaultValue) {
Assert.notNull(source, "Source must not be null");
Assert.notNull(function, "Function must not be null");
return Streamable.of(source).stream()//
.map(function::apply)//
.filter(it -> !it.equals(defaultValue))//
.findFirst().orElse(defaultValue);
}
/**
* Invokes the given {@link Supplier}s for {@link Optional} results one by one and returns the first non-empty one.
*
* @param suppliers must not be {@literal null}.
* @return
*/
@SafeVarargs
static Optional firstNonEmpty(Supplier>... suppliers) {
Assert.notNull(suppliers, "Suppliers must not be null");
return firstNonEmpty(Streamable.of(suppliers));
}
/**
* Invokes the given {@link Supplier}s for {@link Optional} results one by one and returns the first non-empty one.
*
* @param suppliers must not be {@literal null}.
* @return
*/
static Optional firstNonEmpty(Iterable>> suppliers) {
Assert.notNull(suppliers, "Suppliers must not be null");
return Streamable.of(suppliers).stream()//
.map(Supplier::get)//
.filter(Optional::isPresent)//
.findFirst().orElse(Optional.empty());
}
/**
* Returns the next element of the given {@link Iterator} or {@link Optional#empty()} in case there is no next
* element.
*
* @param iterator must not be {@literal null}.
* @return
*/
static Optional next(Iterator iterator) {
Assert.notNull(iterator, "Iterator must not be null");
return iterator.hasNext() ? Optional.of(iterator.next()) : Optional.empty();
}
/**
* Returns a {@link Pair} if both {@link Optional} instances have values or {@link Optional#empty()} if one or both
* are missing.
*
* @param left
* @param right
* @return
*/
static Optional> withBoth(Optional left, Optional right) {
return left.flatMap(l -> right.map(r -> Pair.of(l, r)));
}
/**
* Invokes the given {@link BiConsumer} if all given {@link Optional} are present.
*
* @param left must not be {@literal null}.
* @param right must not be {@literal null}.
* @param consumer must not be {@literal null}.
*/
static void ifAllPresent(Optional left, Optional right, BiConsumer consumer) {
Assert.notNull(left, "Optional must not be null");
Assert.notNull(right, "Optional must not be null");
Assert.notNull(consumer, "Consumer must not be null");
mapIfAllPresent(left, right, (l, r) -> {
consumer.accept(l, r);
return null;
});
}
/**
* Maps the values contained in the given {@link Optional} if both of them are present.
*
* @param left must not be {@literal null}.
* @param right must not be {@literal null}.
* @param function must not be {@literal null}.
* @return
*/
static Optional mapIfAllPresent(Optional left, Optional right,
BiFunction function) {
Assert.notNull(left, "Optional must not be null");
Assert.notNull(right, "Optional must not be null");
Assert.notNull(function, "BiFunction must not be null");
return left.flatMap(l -> right.map(r -> function.apply(l, r)));
}
/**
* Invokes the given {@link Consumer} if the {@link Optional} is present or the {@link Runnable} if not.
*
* @param optional must not be {@literal null}.
* @param consumer must not be {@literal null}.
* @param runnable must not be {@literal null}.
*/
static void ifPresentOrElse(Optional optional, Consumer consumer, Runnable runnable) {
Assert.notNull(optional, "Optional must not be null");
Assert.notNull(consumer, "Consumer must not be null");
Assert.notNull(runnable, "Runnable must not be null");
if (optional.isPresent()) {
optional.ifPresent(consumer);
} else {
runnable.run();
}
}
}