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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   *
17   */
18  package org.apache.bcel.generic;
19  
20  import java.io.DataOutputStream;
21  import java.io.IOException;
22  
23  /**
24   * JSR - Jump to subroutine
25   *
26   * @version $Id: JSR.html 1021978 2017-12-09 17:38:21Z ggregory $
27   */
28  public class JSR extends JsrInstruction implements VariableLengthInstruction {
29  
30      /**
31       * Empty constructor needed for Instruction.readInstruction.
32       * Not to be used otherwise.
33       */
34      JSR() {
35      }
36  
37  
38      public JSR(final InstructionHandle target) {
39          super(org.apache.bcel.Const.JSR, target);
40      }
41  
42  
43      /**
44       * Dump instruction as byte code to stream out.
45       * @param out Output stream
46       */
47      @Override
48      public void dump( final DataOutputStream out ) throws IOException {
49          super.setIndex(getTargetOffset());
50          if (super.getOpcode() == org.apache.bcel.Const.JSR) {
51              super.dump(out);
52          } else { // JSR_W
53              super.setIndex(getTargetOffset());
54              out.writeByte(super.getOpcode());
55              out.writeInt(super.getIndex());
56          }
57      }
58  
59  
60      @Override
61      protected int updatePosition( final int offset, final int max_offset ) {
62          final int i = getTargetOffset(); // Depending on old position value
63          setPosition(getPosition() + offset); // Position may be shifted by preceding expansions
64          if (Math.abs(i) >= (Short.MAX_VALUE - max_offset)) { // to large for short (estimate)
65              super.setOpcode(org.apache.bcel.Const.JSR_W);
66              final short old_length = (short) super.getLength();
67              super.setLength(5);
68              return super.getLength() - old_length;
69          }
70          return 0;
71      }
72  
73  
74      /**
75       * Call corresponding visitor method(s). The order is:
76       * Call visitor methods of implemented interfaces first, then
77       * call methods according to the class hierarchy in descending order,
78       * i.e., the most specific visitXXX() call comes last.
79       *
80       * @param v Visitor object
81       */
82      @Override
83      public void accept( final Visitor v ) {
84          v.visitStackProducer(this);
85          v.visitVariableLengthInstruction(this);
86          v.visitBranchInstruction(this);
87          v.visitJsrInstruction(this);
88          v.visitJSR(this);
89      }
90  }