FunctorUtils.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.collections4.functors;
- import java.util.Collection;
- import java.util.Objects;
- import java.util.function.Consumer;
- import java.util.function.Function;
- import org.apache.commons.collections4.Predicate;
- /**
- * Internal utilities for functors.
- *
- * @since 3.0
- */
- final class FunctorUtils {
- /**
- * A very simple method that coerces Predicate<? super T> to Predicate<T>.
- * Due to the {@link Predicate#test(T)} method, Predicate<? super T> is
- * able to be coerced to Predicate<T> without casting issues.
- * <p>
- * This method exists
- * simply as centralized documentation and atomic unchecked warning
- * suppression.
- * </p>
- *
- * @param <T> the type of object the returned predicate should "accept"
- * @param predicate the predicate to coerce.
- * @return the coerced predicate.
- */
- @SuppressWarnings("unchecked")
- static <R extends java.util.function.Predicate<T>, P extends java.util.function.Predicate<? super T>, T> R coerce(final P predicate) {
- return (R) predicate;
- }
- /**
- * A very simple method that coerces Transformer<? super I, ? extends O> to Transformer<I, O>.
- * <p>
- * This method exists
- * simply as centralized documentation and atomic unchecked warning
- * suppression.
- * </p>
- *
- * @param <I> the type of object the returned transformer should "accept"
- * @param <O> the type of object the returned transformer should "produce"
- * @param transformer the transformer to coerce.
- * @return the coerced transformer.
- */
- @SuppressWarnings("unchecked")
- static <R extends Function<I, O>, P extends Function<? super I, ? extends O>, I, O> R coerce(final P transformer) {
- return (R) transformer;
- }
- /**
- * Clones the consumers to ensure that the internal references can't be updated.
- *
- * @param consumers the consumers to copy.
- * @return the cloned consumers.
- */
- @SuppressWarnings("unchecked")
- static <T extends Consumer<?>> T[] copy(final T... consumers) {
- if (consumers == null) {
- return null;
- }
- return consumers.clone();
- }
- /**
- * Clone the predicates to ensure that the internal reference can't be messed with.
- * Due to the {@link Predicate#test(T)} method, Predicate<? super T> is
- * able to be coerced to Predicate<T> without casting issues.
- *
- * @param predicates the predicates to copy
- * @return the cloned predicates
- */
- @SuppressWarnings("unchecked")
- static <T extends java.util.function.Predicate<?>> T[] copy(final T... predicates) {
- if (predicates == null) {
- return null;
- }
- return predicates.clone();
- }
- /**
- * Copy method.
- *
- * @param transformers the transformers to copy
- * @return a clone of the transformers
- */
- @SuppressWarnings("unchecked")
- static <T extends Function<?, ?>> T[] copy(final T... transformers) {
- if (transformers == null) {
- return null;
- }
- return transformers.clone();
- }
- /**
- * Validate the predicates to ensure that all is well.
- *
- * @param predicates the predicates to validate
- * @return predicate array
- */
- static <T> Predicate<? super T>[] validate(final Collection<? extends java.util.function.Predicate<? super T>> predicates) {
- Objects.requireNonNull(predicates, "predicates");
- // convert to array like this to guarantee iterator() ordering
- @SuppressWarnings("unchecked") // OK
- final Predicate<? super T>[] preds = new Predicate[predicates.size()];
- int i = 0;
- for (final java.util.function.Predicate<? super T> predicate : predicates) {
- preds[i] = (Predicate<? super T>) predicate;
- if (preds[i] == null) {
- throw new NullPointerException("predicates[" + i + "]");
- }
- i++;
- }
- return preds;
- }
- /**
- * Validates the consumers to ensure that all is well.
- *
- * @param consumers the consumers to validate.
- */
- static void validate(final Consumer<?>... consumers) {
- Objects.requireNonNull(consumers, "closures");
- for (int i = 0; i < consumers.length; i++) {
- if (consumers[i] == null) {
- throw new NullPointerException("closures[" + i + "]");
- }
- }
- }
- /**
- * Validate method
- *
- * @param functions the transformers to validate
- */
- static void validate(final Function<?, ?>... functions) {
- Objects.requireNonNull(functions, "functions");
- for (int i = 0; i < functions.length; i++) {
- if (functions[i] == null) {
- throw new NullPointerException("functions[" + i + "]");
- }
- }
- }
- /**
- * Validate the predicates to ensure that all is well.
- *
- * @param predicates the predicates to validate
- */
- static void validate(final java.util.function.Predicate<?>... predicates) {
- Objects.requireNonNull(predicates, "predicates");
- for (int i = 0; i < predicates.length; i++) {
- if (predicates[i] == null) {
- throw new NullPointerException("predicates[" + i + "]");
- }
- }
- }
- /**
- * Restricted constructor.
- */
- private FunctorUtils() {
- }
- }