groovy.transform.Sortable Maven / Gradle / Ivy
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* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package groovy.transform;
import org.codehaus.groovy.transform.GroovyASTTransformationClass;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* 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}.
* More examples:
*
* //--------------------------------------------------------------------------
* import groovy.transform.Sortable
* import groovy.transform.ToString
*
* @Sortable
* @ToString
* class Course {
* // Order of properties determines priority when sorting
* String title
* Date beginDate
* Integer maxAttendees // int doesn't implement Comparable, so use Integer
* }
*
*
* final Course groovy = new Course(
* title: 'Groovy', beginDate: new Date() + 7, maxAttendees: 40)
* final Course groovy2 = new Course(
* title: 'Groovy', beginDate: new Date() + 2, maxAttendees: 50)
* final Course grails = new Course(
* title: 'Grails', beginDate: new Date() + 1, maxAttendees: 20)
*
*
* final List<Course> courses = [groovy, groovy2, grails]
* assert courses.last().title == 'Grails'
*
* // Use toSorted() method to sort
* final List<Course> sorted = courses.toSorted()
*
* assert sorted.first().title == 'Grails'
* assert sorted.last().title == 'Groovy'
* assert sorted.maxAttendees == [20, 50, 40]
*
*
* //--------------------------------------------------------------------------
* // Order of fields for includes determines priority when sorting
* import groovy.transform.Sortable
* import groovy.transform.ToString
*
* @Sortable(includes = ['title', 'maxAttendees'])
* // Or @Sortable(excludes = ['beginDate'])
* @ToString
* class Course {
* String title
* Date beginDate
* Integer maxAttendees
* }
*
* final Course groovy = new Course(
* title: 'Groovy', beginDate: new Date() + 7, maxAttendees: 40)
* final Course groovy2 = new Course(
* title: 'Groovy', beginDate: new Date() + 2, maxAttendees: 50)
* final Course grails = new Course(
* title: 'Grails', beginDate: new Date() + 1, maxAttendees: 20)
*
*
* final List<Course> courses = [groovy, groovy2, grails]
*
* // Use toSorted() method to sort
* final List<Course> sorted = courses.toSorted()
*
* assert sorted.first().title == 'Grails'
* assert sorted.last().title == 'Groovy'
* assert sorted.maxAttendees == [20, 40, 50]
*
* //--------------------------------------------------------------------------
* // Static methods to create comparators.
* final Comparator byMaxAttendees = Course.comparatorByMaxAttendees()
* final List<Course> sortedByMaxAttendees = courses.sort(false, byMaxAttendees)
*
* assert sortedByMaxAttendees.maxAttendees == [20, 40, 50]
* // beginDate is not used for sorting
* assert sortedByMaxAttendees[2].beginDate < sortedByMaxAttendees[1].beginDate
*
* assert Course.declaredMethods.name.findAll { it.startsWith('comparatorBy') }.toSorted() == ['comparatorByMaxAttendees', 'comparatorByTitle']
*
*
* @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 {};
}