/*
 * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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package java.lang.classfile.attribute;

import java.lang.constant.ClassDesc;
import java.lang.classfile.Attribute;
import java.lang.classfile.ClassElement;
import java.lang.classfile.constantpool.ClassEntry;
import jdk.internal.classfile.impl.BoundAttribute;
import jdk.internal.classfile.impl.TemporaryConstantPool;
import jdk.internal.classfile.impl.UnboundAttribute;
import jdk.internal.javac.PreviewFeature;

/**
 * Models the {@code NestHost} attribute {@jvms 4.7.28}, which can
 * appear on classes to indicate that this class is a member of a nest.
 * Delivered as a {@link java.lang.classfile.ClassElement} when
 * traversing the elements of a {@link java.lang.classfile.ClassModel}.
 * <p>
 * The attribute does not permit multiple instances in a given location.
 * Subsequent occurrence of the attribute takes precedence during the attributed
 * element build or transformation.
 * <p>
 * The attribute was introduced in the Java SE Platform version 11.
 *
 * @since 22
 */
@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
public sealed interface NestHostAttribute extends Attribute<NestHostAttribute>, ClassElement
        permits BoundAttribute.BoundNestHostAttribute,
                UnboundAttribute.UnboundNestHostAttribute {

    /**
     * {@return the host class of the nest to which this class belongs}
     */
    ClassEntry nestHost();

    /**
     * {@return a {@code NestHost} attribute}
     * @param nestHost the host class of the nest
     */
    static NestHostAttribute of(ClassEntry nestHost) {
        return new UnboundAttribute.UnboundNestHostAttribute(nestHost);
    }

    /**
     * {@return a {@code NestHost} attribute}
     * @param nestHost the host class of the nest
     * @throws IllegalArgumentException if {@code nestHost} represents a primitive type
     */
    static NestHostAttribute of(ClassDesc nestHost) {
        return of(TemporaryConstantPool.INSTANCE.classEntry(nestHost));
    }
}