1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.bcel.generic;
20
21 import java.io.DataOutputStream;
22 import java.io.IOException;
23
24 import org.apache.bcel.Const;
25 import org.apache.bcel.ExceptionConst;
26 import org.apache.bcel.classfile.ConstantPool;
27 import org.apache.bcel.util.ByteSequence;
28
29 /**
30 * INVOKEINTERFACE - Invoke interface method
31 *
32 * <PRE>
33 * Stack: ..., objectref, [arg1, [arg2 ...]] -> ...
34 * </PRE>
35 *
36 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.invokeinterface"> The
37 * invokeinterface instruction in The Java Virtual Machine Specification</a>
38 */
39 public final class INVOKEINTERFACE extends InvokeInstruction {
40
41 private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2
42
43 /**
44 * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
45 */
46 INVOKEINTERFACE() {
47 }
48
49 public INVOKEINTERFACE(final int index, final int nargs) {
50 super(Const.INVOKEINTERFACE, index);
51 super.setLength(5);
52 if (nargs < 1) {
53 throw new ClassGenException("Number of arguments must be > 0 " + nargs);
54 }
55 this.nargs = nargs;
56 }
57
58 /**
59 * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
60 * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
61 *
62 * @param v Visitor object
63 */
64 @Override
65 public void accept(final Visitor v) {
66 v.visitExceptionThrower(this);
67 v.visitTypedInstruction(this);
68 v.visitStackConsumer(this);
69 v.visitStackProducer(this);
70 v.visitLoadClass(this);
71 v.visitCPInstruction(this);
72 v.visitFieldOrMethod(this);
73 v.visitInvokeInstruction(this);
74 v.visitINVOKEINTERFACE(this);
75 }
76
77 @Override
78 public int consumeStack(final ConstantPoolGen cpg) { // nargs is given in byte-code
79 return nargs; // nargs includes this reference
80 }
81
82 /**
83 * Dump instruction as byte code to stream out.
84 *
85 * @param out Output stream
86 */
87 @Override
88 public void dump(final DataOutputStream out) throws IOException {
89 out.writeByte(super.getOpcode());
90 out.writeShort(super.getIndex());
91 out.writeByte(nargs);
92 out.writeByte(0);
93 }
94
95 /**
96 * The <B>count</B> argument according to the Java Language Specification, Second Edition.
97 */
98 public int getCount() {
99 return nargs;
100 }
101
102 @Override
103 public Class<?>[] getExceptions() {
104 return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_INTERFACE_METHOD_RESOLUTION, ExceptionConst.UNSATISFIED_LINK_ERROR,
105 ExceptionConst.ABSTRACT_METHOD_ERROR, ExceptionConst.ILLEGAL_ACCESS_ERROR, ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
106 }
107
108 /**
109 * Reads needed data (i.e., index) from file.
110 */
111 @Override
112 protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
113 super.initFromFile(bytes, wide);
114 super.setLength(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 @Override
123 public String toString(final ConstantPool cp) {
124 return super.toString(cp) + " " + nargs;
125 }
126 }