001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017
018package org.apache.logging.log4j.util;
019
020import org.apache.logging.log4j.message.Message;
021import org.apache.logging.log4j.message.MessageFactory;
022
023
024/**
025 * Utility class for lambda support.
026 */
027public final class LambdaUtil {
028    /**
029     * Private constructor: this class is not intended to be instantiated.
030     */
031    private LambdaUtil() {
032    }
033
034    /**
035     * Converts an array of lambda expressions into an array of their evaluation results.
036     *
037     * @param suppliers an array of lambda expressions or {@code null}
038     * @return an array containing the results of evaluating the lambda expressions (or {@code null} if the suppliers
039     *         array was {@code null}
040     */
041    public static Object[] getAll(final Supplier<?>... suppliers) {
042        if (suppliers == null) {
043            return null;
044        }
045        final Object[] result = new Object[suppliers.length];
046        for (int i = 0; i < result.length; i++) {
047            result[i] = get(suppliers[i]);
048        }
049        return result;
050    }
051
052    /**
053     * Returns the result of evaluating the specified function. If the supplied value is of type Message, this method
054     * returns the result of calling {@code #getFormattedMessage} on that Message.
055     * @param supplier a lambda expression or {@code null}
056     * @return the results of evaluating the lambda expression (or {@code null} if the supplier
057     *         was {@code null}
058     */
059    public static Object get(final Supplier<?> supplier) {
060        if (supplier == null) {
061            return null;
062        }
063        final Object result = supplier.get();
064        return result instanceof Message ? ((Message) result).getFormattedMessage() : result;
065    }
066
067    /**
068     * Returns the Message supplied by the specified function.
069     * @param supplier a lambda expression or {@code null}
070     * @return the Message resulting from evaluating the lambda expression (or {@code null} if the supplier was
071     * {@code null}
072     */
073    public static Message get(final MessageSupplier supplier) {
074        if (supplier == null) {
075            return null;
076        }
077        return supplier.get();
078    }
079
080    /**
081     * Returns a Message, either the value supplied by the specified function, or a new Message created by the specified
082     * Factory.
083     * @param supplier a lambda expression or {@code null}
084     * @return the Message resulting from evaluating the lambda expression or the Message created by the factory for
085     * supplied values that are not of type Message
086     */
087    public static Message getMessage(final Supplier<?> supplier, final MessageFactory messageFactory) {
088        if (supplier == null) {
089            return null;
090        }
091        final Object result = supplier.get();
092        return result instanceof Message ? (Message) result : messageFactory.newMessage(result);
093    }
094}