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1   /*
2    * Copyright  2000-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License"); 
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License. 
15   *
16   */
17  package org.apache.bcel.generic;
18  
19  import java.io.DataOutputStream;
20  import java.io.IOException;
21  import org.apache.bcel.Constants;
22  import org.apache.bcel.ExceptionConstants;
23  import org.apache.bcel.classfile.ConstantPool;
24  import org.apache.bcel.util.ByteSequence;
25  
26  /*** 
27   * INVOKEINTERFACE - Invoke interface method
28   * <PRE>Stack: ..., objectref, [arg1, [arg2 ...]] -&gt; ...</PRE>
29   *
30   * @version $Id: INVOKEINTERFACE.java 386056 2006-03-15 11:31:56Z tcurdt $
31   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
32   */
33  public final class INVOKEINTERFACE extends InvokeInstruction {
34  
35      private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2
36  
37  
38      /***
39       * Empty constructor needed for the Class.newInstance() statement in
40       * Instruction.readInstruction(). Not to be used otherwise.
41       */
42      INVOKEINTERFACE() {
43      }
44  
45  
46      public INVOKEINTERFACE(int index, int nargs) {
47          super(Constants.INVOKEINTERFACE, index);
48          length = 5;
49          if (nargs < 1) {
50              throw new ClassGenException("Number of arguments must be > 0 " + nargs);
51          }
52          this.nargs = nargs;
53      }
54  
55  
56      /***
57       * Dump instruction as byte code to stream out.
58       * @param out Output stream
59       */
60      public void dump( DataOutputStream out ) throws IOException {
61          out.writeByte(opcode);
62          out.writeShort(index);
63          out.writeByte(nargs);
64          out.writeByte(0);
65      }
66  
67  
68      /***
69       * The <B>count</B> argument according to the Java Language Specification,
70       * Second Edition.
71       */
72      public int getCount() {
73          return nargs;
74      }
75  
76  
77      /***
78       * Read needed data (i.e., index) from file.
79       */
80      protected void initFromFile( ByteSequence bytes, boolean wide ) throws IOException {
81          super.initFromFile(bytes, wide);
82          length = 5;
83          nargs = bytes.readUnsignedByte();
84          bytes.readByte(); // Skip 0 byte
85      }
86  
87  
88      /***
89       * @return mnemonic for instruction with symbolic references resolved
90       */
91      public String toString( ConstantPool cp ) {
92          return super.toString(cp) + " " + nargs;
93      }
94  
95  
96      public int consumeStack( ConstantPoolGen cpg ) { // nargs is given in byte-code
97          return nargs; // nargs includes this reference
98      }
99  
100 
101     public Class[] getExceptions() {
102         Class[] cs = new Class[4 + ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length];
103         System.arraycopy(ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION, 0, cs, 0,
104                 ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length);
105         cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length + 3] = ExceptionConstants.INCOMPATIBLE_CLASS_CHANGE_ERROR;
106         cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length + 2] = ExceptionConstants.ILLEGAL_ACCESS_ERROR;
107         cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length + 1] = ExceptionConstants.ABSTRACT_METHOD_ERROR;
108         cs[ExceptionConstants.EXCS_INTERFACE_METHOD_RESOLUTION.length] = ExceptionConstants.UNSATISFIED_LINK_ERROR;
109         return cs;
110     }
111 
112 
113     /***
114      * Call corresponding visitor method(s). The order is:
115      * Call visitor methods of implemented interfaces first, then
116      * call methods according to the class hierarchy in descending order,
117      * i.e., the most specific visitXXX() call comes last.
118      *
119      * @param v Visitor object
120      */
121     public void accept( Visitor v ) {
122         v.visitExceptionThrower(this);
123         v.visitTypedInstruction(this);
124         v.visitStackConsumer(this);
125         v.visitStackProducer(this);
126         v.visitLoadClass(this);
127         v.visitCPInstruction(this);
128         v.visitFieldOrMethod(this);
129         v.visitInvokeInstruction(this);
130         v.visitINVOKEINTERFACE(this);
131     }
132 }