org.checkerframework.framework.qual.PolymorphicQualifier Maven / Gradle / Ivy
package org.checkerframework.framework.qual;
import java.lang.annotation.Annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* A meta-annotation that indicates that an annotation is a polymorphic type qualifier.
*
* Any method written using a polymorphic type qualifier conceptually has two or more versions
* — one version for each qualifier in the qualifier hierarchy. In each version of the method,
* all instances of the polymorphic type qualifier are replaced by one of the other type qualifiers.
*
* @checker_framework.manual #qualifier-polymorphism Qualifier polymorphism
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.ANNOTATION_TYPE})
@AnnotatedFor("nullness")
public @interface PolymorphicQualifier {
/**
* Indicates which type system this annotation refers to (optional, and usually unnecessary). When
* multiple type hierarchies are supported by a single type system, then each polymorphic
* qualifier needs to indicate which sub-hierarchy it belongs to. Do so by passing the top
* qualifier from the given hierarchy.
*
* @return the top qualifier in the hierarchy of this qualifier
*/
// We use the meaningless Annotation.class as default value and
// then ensure there is a single top qualifier to use.
Class value() default Annotation.class;
}