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 jdk.nashorn.internal.codegen.Label;
  29 
  30 /**
  31  * Common base class for jump statements (e.g. {@code break} and {@code continue}).
  32  */
  33 public abstract class JumpStatement extends Statement implements JoinPredecessor {
  34     private static final long serialVersionUID = 1L;
  35 
  36     private final String labelName;
  37     private final LocalVariableConversion conversion;
  38 
  39     /**
  40      * Constructor
  41      *
  42      * @param lineNumber line number
  43      * @param token      token
  44      * @param finish     finish
  45      * @param labelName  label name for break or null if none
  46      */
  47     protected JumpStatement(final int lineNumber, final long token, final int finish, final String labelName) {
  48         super(lineNumber, token, finish);
  49         this.labelName = labelName;
  50         this.conversion = null;
  51     }
  52 
  53     /**
  54      * Copy constructor.
  55      * @param jumpStatement the original jump statement.
  56      * @param conversion a new local variable conversion.
  57      */
  58     protected JumpStatement(final JumpStatement jumpStatement, final LocalVariableConversion conversion) {
  59         super(jumpStatement);
  60         this.labelName = jumpStatement.labelName;
  61         this.conversion = conversion;
  62     }
  63 
  64     @Override
  65     public boolean hasGoto() {
  66         return true;
  67     }
  68 
  69     /**
  70      * Get the label name for this break node
  71      * @return label name, or null if none
  72      */
  73     public String getLabelName() {
  74         return labelName;
  75     }
  76 
  77     @Override
  78     public void toString(final StringBuilder sb, final boolean printType) {
  79         sb.append(getStatementName());
  80 
  81         if (labelName != null) {
  82             sb.append(' ').append(labelName);
  83         }
  84     }
  85 
  86     abstract String getStatementName();
  87 
  88     /**
  89      * Finds the target for this jump statement in a lexical context.
  90      * @param lc the lexical context
  91      * @return the target, or null if not found
  92      */
  93     public abstract BreakableNode getTarget(final LexicalContext lc);
  94 
  95     /**
  96      * Returns the label corresponding to this kind of jump statement (either a break or continue label) in the target.
  97      * @param target the target. Note that it need not be the target of this jump statement, as the method can retrieve
  98      * a label on any passed target as long as the target has a label of the requisite kind. Of course, it is advisable
  99      * to invoke the method on a jump statement that targets the breakable.
 100      * @return the label of the target corresponding to the kind of jump statement.
 101      * @throws ClassCastException if invoked on the kind of breakable node that this jump statement is not prepared to
 102      * handle.
 103      */
 104     abstract Label getTargetLabel(final BreakableNode target);
 105 
 106     /**
 107      * Returns the label this jump statement targets.
 108      * @param lc the lexical context
 109      * @return the label this jump statement targets.
 110      */
 111     public Label getTargetLabel(final LexicalContext lc) {
 112         return getTargetLabel(getTarget(lc));
 113     }
 114 
 115     /**
 116      * Returns the limit node for popping scopes when this jump statement is effected.
 117      * @param lc the current lexical context
 118      * @return the limit node for popping scopes when this jump statement is effected.
 119      */
 120     public LexicalContextNode getPopScopeLimit(final LexicalContext lc) {
 121         // In most cases (break and continue) this is equal to the target.
 122         return getTarget(lc);
 123     }
 124 
 125     @Override
 126     public JumpStatement setLocalVariableConversion(final LexicalContext lc, final LocalVariableConversion conversion) {
 127         if(this.conversion == conversion) {
 128             return this;
 129         }
 130         return createNewJumpStatement(conversion);
 131     }
 132 
 133     abstract JumpStatement createNewJumpStatement(LocalVariableConversion newConversion);
 134 
 135     @Override
 136     public LocalVariableConversion getLocalVariableConversion() {
 137         return conversion;
 138     }
 139 }