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Groovy: A powerful, dynamic language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* 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
* "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.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* The AnnotationCollector can be used to define aliases for groups of
* annotations. The Alias needs to be a class or annotation annotated with
* AnnotationCollector, otherwise nothing is required. The alias will be
* replaced on the AST level and will never appear in later. Any members of the
* class or annotation will be ignored, but could be used by a custom processor.
* Annotation arguments are mapped to the aliased annotations
* if existing. Should the default processor not be able to map one of the
* arguments and error will be given. Is this not wished or if you want a
* different mapping a custom processor has to be used. There are two ways of
* using the alias. The first way is by providing the annotations as list/array:
*
* import groovy.transform.*
* @AnnotationCollector([ToString, EqualsAndHashCode, Immutable])
* @interface Alias {}
* @Alias(excludes=["a"])
* class Foo {
* Integer a, b
* }
* assert Foo.class.annotations.size()==3
* assert new Foo(1,2).toString() == "Foo(2)"
*
* In the example above we have Alias as the alias annotation and an argument
* excludes which will be mapped to ToString and EqualsAndHashCode. Immutable
* doesn't have excludes, thus nothing will be done there.
* The other way is to add annotations to the alias:
*
* import groovy.transform.*
* @ToString(excludes=["a"])
* @EqualsAndHashCode
* @Immutable
* @AnnotationCollector
* @interface Alias {}
*
* @Alias
* class Foo {
* Integer a, b
* }
* assert Foo.class.annotations.size()==3
* assert new Foo(1,2).toString() == "Foo(2)"
*
* In the example above we have again Alias as the alias annotation, but
* this time the argument is part of the alias. Instead of mapping excludes to
* ToString as well as EqualsAndHashCode, only ToString will have the excludes.
* Again the alias can have an argument excludes, which would overwrite the
* excludes given in from the definition and be mapped to ToString as well as
* EqualsAndHashCode.
* If both ways are combined, then the list overwrites annotation usage.
* NOTE: The aliasing does not support aliasing of aliased annotations.
*
* @author Jochen "blackdrag" Theodorou
* @see org.codehaus.groovy.transform.AnnotationCollectorTransform
*/
@java.lang.annotation.Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.ANNOTATION_TYPE, ElementType.TYPE})
public @interface AnnotationCollector {
/**
* Processor used for computing custom logic or the list of annotations, or
* both. The default is org.codehaus.groovy.transform.AnnotationCollectorTransform.
* Custom processors need to extend that class.
*/
String processor() default "org.codehaus.groovy.transform.AnnotationCollectorTransform";
/**
* List of aliased annotations.
*/
Class[] value() default {};
}