Source code

    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}