1   package org.apache.bcel.generic;
2   
3   /* ====================================================================
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution,
22   *    if any, must include the following acknowledgment:
23   *       "This product includes software developed by the
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowledgment may appear in the software itself,
26   *    if and wherever such third-party acknowledgments normally appear.
27   *
28   * 4. The names "Apache" and "Apache Software Foundation" and
29   *    "Apache BCEL" must not be used to endorse or promote products
30   *    derived from this software without prior written permission. For
31   *    written permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache",
34   *    "Apache BCEL", nor may "Apache" appear in their name, without
35   *    prior written permission of the Apache Software Foundation.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
53   * information on the Apache Software Foundation, please see
54   * <http://www.apache.org/>.
55   */
56  import org.apache.bcel.classfile.ConstantPool;
57  import org.apache.bcel.Constants;
58  import org.apache.bcel.ExceptionConstants;
59  
60  import java.io.*;
61  import org.apache.bcel.util.ByteSequence;
62  
63  /*** 
64   * INVOKEINTERFACE - Invoke interface method
65   * <PRE>Stack: ..., objectref, [arg1, [arg2 ...]] -> ...</PRE>
66   *
67   * @version $Id: INVOKEINTERFACE.java,v 1.1.1.1 2001/10/29 20:00:16 jvanzyl Exp $
68   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69   */
70  public final class INVOKEINTERFACE extends InvokeInstruction {
71    private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2
72  
73    /***
74     * Empty constructor needed for the Class.newInstance() statement in
75     * Instruction.readInstruction(). Not to be used otherwise.
76     */
77    INVOKEINTERFACE() {}
78  
79    public INVOKEINTERFACE(int index, int nargs) {
80      super(Constants.INVOKEINTERFACE, index);
81      length = 5;
82  
83      if(nargs < 1)
84        throw new ClassGenException("Number of arguments must be > 0 " + nargs);
85  
86      this.nargs = nargs;
87    }
88  
89    /***
90     * Dump instruction as byte code to stream out.
91     * @param out Output stream
92     */
93    public void dump(DataOutputStream out) throws IOException {
94      out.writeByte(opcode);
95      out.writeShort(index);
96      out.writeByte(nargs);
97      out.writeByte(0);
98    }
99  
100   /***
101    * The <B>count</B> argument according to the Java Language Specification,
102    * Second Edition.
103    */
104   public int getCount() { return nargs; }
105 
106   /***
107    * Read needed data (i.e., index) from file.
108    */
109   protected void initFromFile(ByteSequence bytes, boolean wide)
110        throws IOException
111   {
112     super.initFromFile(bytes, wide);
113 
114     length = 5;
115     nargs = bytes.readUnsignedByte();
116     bytes.readByte(); // Skip 0 byte
117   }
118 
119   /***
120    * @return mnemonic for instruction with symbolic references resolved
121    */
122   public String toString(ConstantPool cp) {
123     return super.toString(cp) + " " + nargs;
124   }
125 
126   public int consumeStack(ConstantPoolGen cpg) { // nargs is given in byte-code
127     return nargs;  // nargs includes this reference
128   }
129 
130   public Class[] getExceptions() {
131     Class[] cs = new Class[4 + ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length];
132 
133     System.arraycopy(ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION, 0,
134 		     cs, 0, ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length);
135 
136     cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+3] = ExceptionConstants.INCOMPATIBLE_CLASS_CHANGE_ERROR;
137     cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+2] = ExceptionConstants.ILLEGAL_ACCESS_ERROR;
138     cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length+1] = ExceptionConstants.ABSTRACT_METHOD_ERROR;
139     cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length]   = ExceptionConstants.UNSATISFIED_LINK_ERROR;
140 
141     return cs;
142   }
143 
144   /***
145    * Call corresponding visitor method(s). The order is:
146    * Call visitor methods of implemented interfaces first, then
147    * call methods according to the class hierarchy in descending order,
148    * i.e., the most specific visitXXX() call comes last.
149    *
150    * @param v Visitor object
151    */
152   public void accept(Visitor v) {
153     v.visitExceptionThrower(this);
154     v.visitTypedInstruction(this);
155     v.visitStackConsumer(this);
156     v.visitStackProducer(this);
157     v.visitLoadClass(this);
158     v.visitCPInstruction(this);
159     v.visitFieldOrMethod(this);
160     v.visitInvokeInstruction(this);
161     v.visitINVOKEINTERFACE(this);
162   }
163 }
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