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.classfile;
19 
20 import java.io.DataInput;
21 import java.io.DataOutputStream;
22 import java.io.IOException;
23 
24 import org.apache.bcel.Const;
25 
26 /**
27  * This class represents a stack map attribute used for
28  * preverification of Java classes for the <a
29  * href="http://java.sun.com/j2me/"> Java 2 Micro Edition</a>
30  * (J2ME). This attribute is used by the <a
31  * href="http://java.sun.com/products/cldc/">KVM</a> and contained
32  * within the Code attribute of a method. See CLDC specification
33  * �5.3.1.2
34  *
35  * @version $Id$
36  * @see     Code
37  * @see     StackMapEntry
38  * @see     StackMapType
39  */
40 public final class StackMap extends Attribute {
41 
42     private StackMapEntry[] map; // Table of stack map entries
43 
44 
45     /*
46      * @param name_index Index of name
47      * @param length Content length in bytes
48      * @param map Table of stack map entries
49      * @param constant_pool Array of constants
50      */
StackMap(final int name_index, final int length, final StackMapEntry[] map, final ConstantPool constant_pool)51     public StackMap(final int name_index, final int length, final StackMapEntry[] map, final ConstantPool constant_pool) {
52         super(Const.ATTR_STACK_MAP, name_index, length, constant_pool);
53         this.map = map;
54     }
55 
56 
57     /**
58      * Construct object from input stream.
59      *
60      * @param name_index Index of name
61      * @param length Content length in bytes
62      * @param input Input stream
63      * @param constant_pool Array of constants
64      * @throws IOException
65      */
StackMap(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)66     StackMap(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
67         this(name_index, length, (StackMapEntry[]) null, constant_pool);
68         final int map_length = input.readUnsignedShort();
69         map = new StackMapEntry[map_length];
70         for (int i = 0; i < map_length; i++) {
71             map[i] = new StackMapEntry(input, constant_pool);
72         }
73     }
74 
75 
76     /**
77      * Dump stack map table attribute to file stream in binary format.
78      *
79      * @param file Output file stream
80      * @throws IOException
81      */
82     @Override
dump( final DataOutputStream file )83     public final void dump( final DataOutputStream file ) throws IOException {
84         super.dump(file);
85         file.writeShort(map.length);
86         for (final StackMapEntry entry : map) {
87             entry.dump(file);
88         }
89     }
90 
91 
92     /**
93      * @return Array of stack map entries
94      */
getStackMap()95     public final StackMapEntry[] getStackMap() {
96         return map;
97     }
98 
99 
100     /**
101      * @param map Array of stack map entries
102      */
setStackMap( final StackMapEntry[] map )103     public final void setStackMap( final StackMapEntry[] map ) {
104         this.map = map;
105         int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
106         for (final StackMapEntry element : map) {
107             len += element.getMapEntrySize();
108         }
109         setLength(len);
110     }
111 
112 
113     /**
114      * @return String representation.
115      */
116     @Override
toString()117     public final String toString() {
118         final StringBuilder buf = new StringBuilder("StackMap(");
119         for (int i = 0; i < map.length; i++) {
120             buf.append(map[i]);
121             if (i < map.length - 1) {
122                 buf.append(", ");
123             }
124         }
125         buf.append(')');
126         return buf.toString();
127     }
128 
129 
130     /**
131      * @return deep copy of this attribute
132      */
133     @Override
copy( final ConstantPool _constant_pool )134     public Attribute copy( final ConstantPool _constant_pool ) {
135         final StackMap c = (StackMap) clone();
136         c.map = new StackMapEntry[map.length];
137         for (int i = 0; i < map.length; i++) {
138             c.map[i] = map[i].copy();
139         }
140         c.setConstantPool(_constant_pool);
141         return c;
142     }
143 
144 
145     /**
146      * Called by objects that are traversing the nodes of the tree implicitely
147      * defined by the contents of a Java class. I.e., the hierarchy of methods,
148      * fields, attributes, etc. spawns a tree of objects.
149      *
150      * @param v Visitor object
151      */
152     @Override
accept( final Visitor v )153     public void accept( final Visitor v ) {
154         v.visitStackMap(this);
155     }
156 
157 
getMapLength()158     public final int getMapLength() {
159         return map == null ? 0 : map.length;
160     }
161 }
162