resource-predicates/src/main/java/org/apache/sling/resource/predicates/Conditions.java

/*
 * 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 org.apache.sling.resource.predicates;

import java.util.Objects;
import java.util.function.Predicate;

/**
 * A collection of terms to assist in building a fluent api. These terms may not
 * have functionality other than providing syntax sugar over existing features,
 * or merely providing context for other terms
 *
 */
public class Conditions {

    /**
     * Syntactic sugar to provide context for the builder
     * 
     * @param predicate
     *            to be wrapped
     * @return the predicate that was passed in
     */
    public static <T> Predicate<T> where(Predicate<T> predicate) {
        return predicate;
    }

    /**
     * Syntactic sugar to provide context for the builder
     * 
     * @param predicate
     *            to be wrapped
     * @return the predicate that was passed in
     */
    public static <T> Predicate<T> when(Predicate<T> predicate) {
        return predicate;
    }

    /**
     * 'or' equivalent. only evaluates the second predicate if the first one fails
     * 
     * @param firstPredicate
     *            always evaluated
     * @param secondPredicate
     *            evaluated if firstPredicate returns false
     * @return a new predicate which wraps the or method on the firstPredicate
     */
    public static <T> Predicate<T> either(final Predicate<T> firstPredicate, final Predicate<T> secondPredicate) {
        Objects.requireNonNull(firstPredicate, "predicate may not be null");
        Objects.requireNonNull(secondPredicate, "predicate may not be null");
        return firstPredicate.or(secondPredicate);
    }

}