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 * Copyright (c) 2005, 2019, 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,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package com.sun.source.tree;

import java.util.List;

/**

 * A tree node for a {@code case} in a {@code switch} statement or expression.

 *

 * For example:

 * <pre>

 *   case <em>expression</em> :

 *       <em>statements</em>

 *

 *   default :

 *       <em>statements</em>

 * </pre>

 *

 * @jls 14.11 The switch Statement

 *

 * @author Peter von der Ahé

 * @author Jonathan Gibbons

 * @since 1.6

 */

public interface CaseTree extends Tree {

    /**

     * Returns the expression for the case, or

     * {@code null} if this is the default case.

     * If this case has multiple labels, returns the first label.

     * @return the expression for the case, or null

     */

    ExpressionTree getExpression();

    /**

     * Returns the labels for this case.

     * For default case, returns an empty list.

     *

     * @return labels for this case

     * @since 12

     *

     * @preview This method is modeling a case with multiple labels,

     * which is part of a preview feature and may be removed

     * if the preview feature is removed.

     */

    @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.SWITCH_EXPRESSIONS)

    List<? extends ExpressionTree> getExpressions();

    /**

     * For case with kind {@linkplain CaseKind#STATEMENT},

     * returns the statements labeled by the case.

     * Returns {@code null} for case with kind

     * {@linkplain CaseKind#RULE}.

     * @return the statements labeled by the case or null

     */

    List<? extends StatementTree> getStatements();

    /**

     * For case with kind {@linkplain CaseKind#RULE},

     * returns the statement or expression after the arrow.

     * Returns {@code null} for case with kind

     * {@linkplain CaseKind#STATEMENT}.

     *

     * @return case value or null

     * @since 12

     */

    @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.SWITCH_EXPRESSIONS)

    public default Tree getBody() {

        return null;

    }

    /**

     * Returns the kind of this case.

     *

     * @return the kind of this case

     * @since 12

     */

    @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.SWITCH_EXPRESSIONS)

    @SuppressWarnings("preview")

    public default CaseKind getCaseKind() {

        return CaseKind.STATEMENT;

    }

    /**

     * The syntatic form of this case:

     * <ul>

     *     <li>STATEMENT: {@code case <expression>: <statements>}</li>

     *     <li>RULE: {@code case <expression> -> <expression>/<statement>}</li>

     * </ul>

     *

     * @since 12

     */

    @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.SWITCH_EXPRESSIONS)

    @SuppressWarnings("preview")

    public enum CaseKind {

        /**

         * Case is in the form: {@code case <expression>: <statements>}.

         */

        STATEMENT,

        /**

         * Case is in the form: {@code case <expression> -> <expression>}.

         */

        RULE;

    }

}