1 /*
   2  * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.ir;
  27 
  28 import java.util.Arrays;
  29 import java.util.List;
  30 
  31 import jdk.nashorn.internal.codegen.Label;
  32 import jdk.nashorn.internal.ir.annotations.Immutable;
  33 
  34 /**
  35  * This class represents a node from which control flow can execute
  36  * a {@code break} statement
  37  */
  38 @Immutable
  39 public abstract class BreakableNode extends LexicalContextNode {
  40 
  41     /** break label. */
  42     protected final Label breakLabel;
  43 
  44     /**
  45      * Constructor
  46      *
  47      * @param lineNumber line number
  48      * @param token      token
  49      * @param finish     finish
  50      * @param breakLabel break label
  51      */
  52     protected BreakableNode(final int lineNumber, final long token, final int finish, final Label breakLabel) {
  53         super(lineNumber, token, finish);
  54         this.breakLabel = breakLabel;
  55     }
  56 
  57     /**
  58      * Copy constructor
  59      *
  60      * @param breakableNode source node
  61      */
  62     protected BreakableNode(final BreakableNode breakableNode) {
  63         super(breakableNode);
  64         this.breakLabel = new Label(breakableNode.getBreakLabel());
  65     }
  66 
  67     @Override
  68     public abstract Node ensureUniqueLabels(final LexicalContext lc);
  69 
  70     /**
  71      * Check whether this can be broken out from without using a label,
  72      * e.g. everything but Blocks, basically
  73      * @return true if breakable without label
  74      */
  75     protected boolean isBreakableWithoutLabel() {
  76         return true;
  77     }
  78 
  79     /**
  80      * Return the break label, i.e. the location to go to on break.
  81      * @return the break label
  82      */
  83     public Label getBreakLabel() {
  84         return breakLabel;
  85     }
  86 
  87     /**
  88      * Return the labels associated with this node. Breakable nodes that
  89      * aren't LoopNodes only have a break label -> the location immediately
  90      * afterwards the node in code
  91      * @return list of labels representing locations around this node
  92      */
  93     public List<Label> getLabels() {
  94         return Arrays.asList(breakLabel);
  95     }
  96 
  97 }