groovy.transform.Sortable Maven / Gradle / Ivy

/*
 * Copyright 2003-2014 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 groovy.transform;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.annotation.ElementType;

import org.codehaus.groovy.transform.GroovyASTTransformationClass;

/**
 * A class annotation used to make a class Comparable by multiple Comparators.
 *
 * As an example, given this class:
 *  * {@code @Sortable} class Person {
 *     String first
 *     String last
 *     Integer born
 * }
 * 
 * The generated Groovy class will:
 * 
 *     implement the {@code Comparable} interface
 *     have a {@code compareTo} method based on the {@code first},
 *     {@code last} and {@code born} properties (priority ordering will be according
 *     to the ordering of property definition, highest first, unless 'includes' is used; in which case,
 *     priority will be according to the order given in the includes list)
 *     have three {@code Comparator} methods named {@code comparatorByFirst},
 *     {@code comparatorByLast} and {@code comparatorByBorn}
 * 
 * The properties within the class must themselves be {@code Comparable} or {@code @Sortable}.
 *
 * @author Andres Almiray
 * @author Paul King
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.SortableASTTransformation")
public @interface Sortable {
    /**
     * Property names to include in the comparison algorithm.
     * Must not be used if 'excludes' is used.
     */
    String[] includes() default {};

    /**
     * Property names to exclude in the comparison algorithm.
     * Must not be used if 'includes' is used.
     */
    String[] excludes() default {};
}