org.ajoberstar.gradle.util.ObjectUtil Maven / Gradle / Ivy

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/*
 * Copyright 2012-2014 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 org.ajoberstar.gradle.util;

import java.util.concurrent.Callable;

import groovy.lang.Closure;

/**
 * Utility class for general {@code Object} related operations.
 * @since 0.1.0
 */
public class ObjectUtil {
	/**
	 * Cannot instantiate
	 * @throws AssertionError always
	 */
	private ObjectUtil() {
		throw new AssertionError("Cannot instantiate this class");
	}
	
	/**
	 * Unpacks the given object by recursively
	 * calling the {@code call()} method if the
	 * object is a {@code Closure} or {@code Callable}. 
	 * @param obj the object to unpack
	 * @return the unpacked value of the object
	 */
	@SuppressWarnings("rawtypes")
	public static Object unpack(Object obj) {
		Object value = obj;
		while (value != null) {
			if (value instanceof Closure) {
				value = ((Closure) value).call();
			} else if (value instanceof Callable) {
				try {
					value = ((Callable) value).call();
				} catch (Exception e) {
					throw new RuntimeException(e);
				}
			} else {
				return value;
			}
		}
		return value;
	}
	
	/**
	 * Unpacks the given object to its {@code String}
	 * value.  Same behavior as the other {@code unpack}
	 * method ending with a call to {@code toString()}.
	 * @param obj the value to unpack
	 * @return the unpacked string value
	 * @see ObjectUtil#unpack(Object)
	 */
	public static String unpackString(Object obj) {
		Object value = unpack(obj);
		return value == null ? null : value.toString();
	}
}