    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;
    023import java.util.Arrays;
    024
    025import org.apache.bcel.Const;
    026
    027/**
    028 * This class represents a stack map attribute used for preverification of Java classes for the
    029 * <a href="http://java.sun.com/j2me/"> Java 2 Micro Edition</a> (J2ME). This attribute is used by the
    030 * <a href="http://java.sun.com/products/cldc/">KVM</a> and contained within the Code attribute of a method. See CLDC
    031 * specification �5.3.1.2
    032 *
    033 * @see Code
    034 * @see StackMapEntry
    035 * @see StackMapType
    036 */
    037public final class StackMap extends Attribute {
    038
    039    private StackMapEntry[] table; // Table of stack map entries
    040
    041    /**
    042     * Construct object from input stream.
    043     *
    044     * @param name_index Index of name
    045     * @param length Content length in bytes
    046     * @param input Input stream
    047     * @param constant_pool Array of constants
    048     * @throws IOException if an I/O error occurs.
    049     */
    050    StackMap(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    051        this(name_index, length, (StackMapEntry[]) null, constant_pool);
    052        final int map_length = input.readUnsignedShort();
    053        table = new StackMapEntry[map_length];
    054        for (int i = 0; i < map_length; i++) {
    055            table[i] = new StackMapEntry(input, constant_pool);
    056        }
    057    }
    058
    059    /*
    060     * @param name_index Index of name
    061     *
    062     * @param length Content length in bytes
    063     *
    064     * @param map Table of stack map entries
    065     *
    066     * @param constant_pool Array of constants
    067     */
    068    public StackMap(final int name_index, final int length, final StackMapEntry[] map, final ConstantPool constant_pool) {
    069        super(Const.ATTR_STACK_MAP, name_index, length, constant_pool);
    070        this.table = map;
    071    }
    072
    073    /**
    074     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    075     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    076     *
    077     * @param v Visitor object
    078     */
    079    @Override
    080    public void accept(final Visitor v) {
    081        v.visitStackMap(this);
    082    }
    083
    084    /**
    085     * @return deep copy of this attribute
    086     */
    087    @Override
    088    public Attribute copy(final ConstantPool constantPool) {
    089        final StackMap c = (StackMap) clone();
    090        c.table = new StackMapEntry[table.length];
    091        Arrays.setAll(c.table, i -> table[i].copy());
    092        c.setConstantPool(constantPool);
    093        return c;
    094    }
    095
    096    /**
    097     * Dump stack map table attribute to file stream in binary format.
    098     *
    099     * @param file Output file stream
    100     * @throws IOException if an I/O error occurs.
    101     */
    102    @Override
    103    public void dump(final DataOutputStream file) throws IOException {
    104        super.dump(file);
    105        file.writeShort(table.length);
    106        for (final StackMapEntry entry : table) {
    107            entry.dump(file);
    108        }
    109    }
    110
    111    public int getMapLength() {
    112        return table == null ? 0 : table.length;
    113    }
    114
    115    /**
    116     * @return Array of stack map entries
    117     */
    118    public StackMapEntry[] getStackMap() {
    119        return table;
    120    }
    121
    122    /**
    123     * @param table Array of stack map entries
    124     */
    125    public void setStackMap(final StackMapEntry[] table) {
    126        this.table = table;
    127        int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
    128        for (final StackMapEntry element : table) {
    129            len += element.getMapEntrySize();
    130        }
    131        setLength(len);
    132    }
    133
    134    /**
    135     * @return String representation.
    136     */
    137    @Override
    138    public String toString() {
    139        final StringBuilder buf = new StringBuilder("StackMap(");
    140        int running_offset = -1; // no +1 on first entry
    141        for (int i = 0; i < table.length; i++) {
    142            running_offset = table[i].getByteCodeOffset() + running_offset + 1;
    143            buf.append(String.format("%n@%03d %s", running_offset, table[i]));
    144            if (i < table.length - 1) {
    145                buf.append(", ");
    146            }
    147        }
    148        buf.append(')');
    149        return buf.toString();
    150    }
    151}