1 /*
   2  * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.source.tree;
  27 
  28 import java.util.List;
  29 
  30 /**
  31  * A tree node for a {@code case} in a {@code switch} statement or expression.
  32  *
  33  * For example:
  34  * <pre>
  35  *   case <em>expression</em> :
  36  *       <em>statements</em>
  37  *
  38  *   default :
  39  *       <em>statements</em>
  40  * </pre>
  41  *
  42  * @jls 14.11 The switch Statement
  43  *
  44  * @author Peter von der Ah&eacute;
  45  * @author Jonathan Gibbons
  46  * @since 1.6
  47  */
  48 public interface CaseTree extends Tree {
  49     /**
  50      * Returns the expression for the case, or
  51      * {@code null} if this is the default case.
  52      * If this case has multiple labels, returns the first label.
  53      * @return the expression for the case, or null
  54      * @deprecated Please use {@link #getExpressions()}.
  55      */
  56     @Deprecated
  57     ExpressionTree getExpression();
  58 
  59     /**
  60      * Returns the labels for this case.
  61      * For default case, returns an empty list.
  62      *
  63      * @return labels for this case
  64      * @since 12
  65      */
  66     List<? extends ExpressionTree> getExpressions();
  67 
  68     /**
  69      * For case with kind {@linkplain CaseKind#STATEMENT},
  70      * returns the statements labeled by the case.
  71      * Returns {@code null} for case with kind
  72      * {@linkplain CaseKind#RULE}.
  73      * @return the statements labeled by the case or null
  74      */
  75     List<? extends StatementTree> getStatements();
  76 
  77     /**
  78      * For case with kind {@linkplain CaseKind#RULE},
  79      * returns the statement or expression after the arrow.
  80      * Returns {@code null} for case with kind
  81      * {@linkplain CaseKind#STATEMENT}.
  82      *
  83      * @return case value or null
  84      * @since 12
  85      */
  86     public default Tree getBody() {
  87         return null;
  88     }
  89 
  90     /**
  91      * Returns the kind of this case.
  92      *
  93      * @return the kind of this case
  94      * @since 12
  95      */
  96     public default CaseKind getCaseKind() {
  97         return CaseKind.STATEMENT;
  98     }
  99 
 100     /**
 101      * The syntatic form of this case:
 102      * <ul>
 103      *     <li>STATEMENT: {@code case <expression>: <statements>}</li>
 104      *     <li>RULE: {@code case <expression> -> <expression>/<statement>}</li>
 105      * </ul>
 106      *
 107      * @since 12
 108      */
 109     public enum CaseKind {
 110         /**
 111          * Case is in the form: {@code case <expression>: <statements>}.
 112          */
 113         STATEMENT,
 114         /**
 115          * Case is in the form: {@code case <expression> -> <expression>}.
 116          */
 117         RULE;
 118     }
 119 }