package org.checkerframework.checker.nullness.qual;
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;
import org.checkerframework.framework.qual.PolymorphicQualifier;
/**
* A polymorphic qualifier for the Map Key (@KeyFor) type system.
*
* <p>Any method written using {@code @PolyKeyFor} conceptually has an arbitrary number of versions:
* one in which every instance of {@code @PolyKeyFor} has been replaced by {@code @}{@link
* UnknownKeyFor}, one in which every instance of {@code @}{@link PolyKeyFor} has been replaced by
* {@code @}{@link KeyForBottom}, and ones in which every instance of {@code @PolyKeyFor} has been
* replaced by {@code @}{@code KeyFor}, for every possible combination of map arguments.
*
* @checker_framework.manual #nullness-checker Nullness Checker
* @checker_framework.manual #qualifier-polymorphism Qualifier polymorphism
*/
@Documented
@PolymorphicQualifier(UnknownKeyFor.class)
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface PolyKeyFor {}