001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.classfile;
020
021import java.io.DataInput;
022import java.io.DataOutputStream;
023import java.io.IOException;
024import java.util.Arrays;
025
026import org.apache.bcel.Const;
027import org.apache.bcel.util.Args;
028
029/**
030 * This class represents a stack map attribute used for preverification of Java classes for the
031 * <a href="https://java.sun.com/j2me/"> Java 2 Micro Edition</a> (J2ME). This attribute is used by the
032 * <a href="https://java.sun.com/products/cldc/">KVM</a> and contained within the Code attribute of a method. See CLDC
033 * specification �5.3.1.2
034 *
035 * <pre>
036 * StackMapTable_attribute {
037 *   u2              attribute_name_index;
038 *   u4              attribute_length;
039 *   u2              number_of_entries;
040 *   stack_map_frame entries[number_of_entries];
041 * }
042 * </pre>
043 *
044 * @see Code
045 * @see StackMapEntry
046 * @see StackMapType
047 */
048public final class StackMap extends Attribute {
049
050    private StackMapEntry[] table; // Table of stack map entries
051
052    /**
053     * Constructs object from input stream.
054     *
055     * @param nameIndex Index of name
056     * @param length Content length in bytes
057     * @param dataInput Input stream
058     * @param constantPool Array of constants
059     * @throws IOException if an I/O error occurs.
060     */
061    StackMap(final int nameIndex, final int length, final DataInput dataInput, final ConstantPool constantPool) throws IOException {
062        this(nameIndex, length, (StackMapEntry[]) null, constantPool);
063        final int mapLength = dataInput.readUnsignedShort();
064        table = new StackMapEntry[mapLength];
065        for (int i = 0; i < mapLength; i++) {
066            table[i] = new StackMapEntry(dataInput, constantPool);
067        }
068    }
069
070    /*
071     * @param nameIndex Index of name
072     * @param length Content length in bytes
073     * @param map Table of stack map entries
074     * @param constantPool Array of constants
075     */
076    public StackMap(final int nameIndex, final int length, final StackMapEntry[] table, final ConstantPool constantPool) {
077        super(Const.ATTR_STACK_MAP, nameIndex, length, constantPool);
078        this.table = table != null ? table : StackMapEntry.EMPTY_ARRAY;
079        Args.requireU2(this.table.length, "table.length");
080    }
081
082    /**
083     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
084     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
085     *
086     * @param v Visitor object
087     */
088    @Override
089    public void accept(final Visitor v) {
090        v.visitStackMap(this);
091    }
092
093    /**
094     * @return deep copy of this attribute
095     */
096    @Override
097    public Attribute copy(final ConstantPool constantPool) {
098        final StackMap c = (StackMap) clone();
099        c.table = new StackMapEntry[table.length];
100        Arrays.setAll(c.table, i -> table[i].copy());
101        c.setConstantPool(constantPool);
102        return c;
103    }
104
105    /**
106     * Dump stack map table attribute to file stream in binary format.
107     *
108     * @param file Output file stream
109     * @throws IOException if an I/O error occurs.
110     */
111    @Override
112    public void dump(final DataOutputStream file) throws IOException {
113        super.dump(file);
114        file.writeShort(table.length);
115        for (final StackMapEntry entry : table) {
116            entry.dump(file);
117        }
118    }
119
120    public int getMapLength() {
121        return table.length;
122    }
123
124    /**
125     * @return Array of stack map entries
126     */
127    public StackMapEntry[] getStackMap() {
128        return table;
129    }
130
131    /**
132     * @param table Array of stack map entries
133     */
134    public void setStackMap(final StackMapEntry[] table) {
135        this.table = table != null ? table : StackMapEntry.EMPTY_ARRAY;
136        int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
137        for (final StackMapEntry element : this.table) {
138            len += element.getMapEntrySize();
139        }
140        setLength(len);
141    }
142
143    /**
144     * @return String representation.
145     */
146    @Override
147    public String toString() {
148        final StringBuilder buf = new StringBuilder("StackMap(");
149        int runningOffset = -1; // no +1 on first entry
150        for (int i = 0; i < table.length; i++) {
151            runningOffset = table[i].getByteCodeOffset() + runningOffset + 1;
152            buf.append(String.format("%n@%03d %s", runningOffset, table[i]));
153            if (i < table.length - 1) {
154                buf.append(", ");
155            }
156        }
157        buf.append(')');
158        return buf.toString();
159    }
160}