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 */
017package org.apache.bcel.classfile;
018
019import java.io.DataInput;
020import java.io.DataOutputStream;
021import java.io.IOException;
022import java.util.Arrays;
023
024import org.apache.bcel.Const;
025
026/**
027 * This class represents a stack map attribute used for preverification of Java classes for the
028 * <a href="http://java.sun.com/j2me/"> Java 2 Micro Edition</a> (J2ME). This attribute is used by the
029 * <a href="http://java.sun.com/products/cldc/">KVM</a> and contained within the Code attribute of a method. See CLDC
030 * specification �5.3.1.2
031 *
032 * @see Code
033 * @see StackMapEntry
034 * @see StackMapType
035 */
036public final class StackMap extends Attribute {
037
038    private StackMapEntry[] table; // Table of stack map entries
039
040    /**
041     * Construct object from input stream.
042     *
043     * @param nameIndex Index of name
044     * @param length Content length in bytes
045     * @param input Input stream
046     * @param constantPool Array of constants
047     * @throws IOException if an I/O error occurs.
048     */
049    StackMap(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
050        this(nameIndex, length, (StackMapEntry[]) null, constantPool);
051        final int mapLength = input.readUnsignedShort();
052        table = new StackMapEntry[mapLength];
053        for (int i = 0; i < mapLength; i++) {
054            table[i] = new StackMapEntry(input, constantPool);
055        }
056    }
057
058    /*
059     * @param nameIndex Index of name
060     *
061     * @param length Content length in bytes
062     *
063     * @param map Table of stack map entries
064     *
065     * @param constantPool Array of constants
066     */
067    public StackMap(final int nameIndex, final int length, final StackMapEntry[] map, final ConstantPool constantPool) {
068        super(Const.ATTR_STACK_MAP, nameIndex, length, constantPool);
069        this.table = map;
070    }
071
072    /**
073     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
074     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
075     *
076     * @param v Visitor object
077     */
078    @Override
079    public void accept(final Visitor v) {
080        v.visitStackMap(this);
081    }
082
083    /**
084     * @return deep copy of this attribute
085     */
086    @Override
087    public Attribute copy(final ConstantPool constantPool) {
088        final StackMap c = (StackMap) clone();
089        c.table = new StackMapEntry[table.length];
090        Arrays.setAll(c.table, i -> table[i].copy());
091        c.setConstantPool(constantPool);
092        return c;
093    }
094
095    /**
096     * Dump stack map table attribute to file stream in binary format.
097     *
098     * @param file Output file stream
099     * @throws IOException if an I/O error occurs.
100     */
101    @Override
102    public void dump(final DataOutputStream file) throws IOException {
103        super.dump(file);
104        file.writeShort(table.length);
105        for (final StackMapEntry entry : table) {
106            entry.dump(file);
107        }
108    }
109
110    public int getMapLength() {
111        return table == null ? 0 : table.length;
112    }
113
114    /**
115     * @return Array of stack map entries
116     */
117    public StackMapEntry[] getStackMap() {
118        return table;
119    }
120
121    /**
122     * @param table Array of stack map entries
123     */
124    public void setStackMap(final StackMapEntry[] table) {
125        this.table = table;
126        int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
127        for (final StackMapEntry element : table) {
128            len += element.getMapEntrySize();
129        }
130        setLength(len);
131    }
132
133    /**
134     * @return String representation.
135     */
136    @Override
137    public String toString() {
138        final StringBuilder buf = new StringBuilder("StackMap(");
139        int runningOffset = -1; // no +1 on first entry
140        for (int i = 0; i < table.length; i++) {
141            runningOffset = table[i].getByteCodeOffset() + runningOffset + 1;
142            buf.append(String.format("%n@%03d %s", runningOffset, table[i]));
143            if (i < table.length - 1) {
144                buf.append(", ");
145            }
146        }
147        buf.append(')');
148        return buf.toString();
149    }
150}