001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.classfile;
019
020import java.io.DataInput;
021import java.io.DataOutputStream;
022import java.io.IOException;
023
024import org.apache.bcel.Const;
025
026/**
027 * This class represents a stack map attribute used for
028 * preverification of Java classes for the <a
029 * href="http://java.sun.com/j2me/"> Java 2 Micro Edition</a>
030 * (J2ME). This attribute is used by the <a
031 * href="http://java.sun.com/products/cldc/">KVM</a> and contained
032 * within the Code attribute of a method. See CLDC specification
033 * �5.3.1.2
034 *
035 * @see     Code
036 * @see     StackMapEntry
037 * @see     StackMapType
038 */
039public final class StackMap extends Attribute {
040
041    private StackMapEntry[] map; // Table of stack map entries
042
043
044    /*
045     * @param name_index Index of name
046     * @param length Content length in bytes
047     * @param map Table of stack map entries
048     * @param constant_pool Array of constants
049     */
050    public StackMap(final int name_index, final int length, final StackMapEntry[] map, final ConstantPool constant_pool) {
051        super(Const.ATTR_STACK_MAP, name_index, length, constant_pool);
052        this.map = map;
053    }
054
055
056    /**
057     * Construct object from input stream.
058     *
059     * @param name_index Index of name
060     * @param length Content length in bytes
061     * @param input Input stream
062     * @param constant_pool Array of constants
063     * @throws IOException
064     */
065    StackMap(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
066        this(name_index, length, (StackMapEntry[]) null, constant_pool);
067        final int map_length = input.readUnsignedShort();
068        map = new StackMapEntry[map_length];
069        for (int i = 0; i < map_length; i++) {
070            map[i] = new StackMapEntry(input, constant_pool);
071        }
072    }
073
074
075    /**
076     * Dump stack map table attribute to file stream in binary format.
077     *
078     * @param file Output file stream
079     * @throws IOException
080     */
081    @Override
082    public void dump( final DataOutputStream file ) throws IOException {
083        super.dump(file);
084        file.writeShort(map.length);
085        for (final StackMapEntry entry : map) {
086            entry.dump(file);
087        }
088    }
089
090
091    /**
092     * @return Array of stack map entries
093     */
094    public StackMapEntry[] getStackMap() {
095        return map;
096    }
097
098
099    /**
100     * @param map Array of stack map entries
101     */
102    public void setStackMap( final StackMapEntry[] map ) {
103        this.map = map;
104        int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
105        for (final StackMapEntry element : map) {
106            len += element.getMapEntrySize();
107        }
108        setLength(len);
109    }
110
111
112    /**
113     * @return String representation.
114     */
115    @Override
116    public String toString() {
117        final StringBuilder buf = new StringBuilder("StackMap(");
118        for (int i = 0; i < map.length; i++) {
119            buf.append(map[i]);
120            if (i < map.length - 1) {
121                buf.append(", ");
122            }
123        }
124        buf.append(')');
125        return buf.toString();
126    }
127
128
129    /**
130     * @return deep copy of this attribute
131     */
132    @Override
133    public Attribute copy( final ConstantPool _constant_pool ) {
134        final StackMap c = (StackMap) clone();
135        c.map = new StackMapEntry[map.length];
136        for (int i = 0; i < map.length; i++) {
137            c.map[i] = map[i].copy();
138        }
139        c.setConstantPool(_constant_pool);
140        return c;
141    }
142
143
144    /**
145     * Called by objects that are traversing the nodes of the tree implicitely
146     * defined by the contents of a Java class. I.e., the hierarchy of methods,
147     * fields, attributes, etc. spawns a tree of objects.
148     *
149     * @param v Visitor object
150     */
151    @Override
152    public void accept( final Visitor v ) {
153        v.visitStackMap(this);
154    }
155
156
157    public int getMapLength() {
158        return map == null ? 0 : map.length;
159    }
160}