    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 * @version $Id$
    036 * @see     Code
    037 * @see     StackMapEntry
    038 * @see     StackMapType
    039 */
    040public final class StackMap extends Attribute {
    041
    042    private StackMapEntry[] map; // Table of stack map entries
    043
    044
    045    /*
    046     * @param name_index Index of name
    047     * @param length Content length in bytes
    048     * @param map Table of stack map entries
    049     * @param constant_pool Array of constants
    050     */
    051    public StackMap(final int name_index, final int length, final StackMapEntry[] map, final ConstantPool constant_pool) {
    052        super(Const.ATTR_STACK_MAP, name_index, length, constant_pool);
    053        this.map = map;
    054    }
    055
    056
    057    /**
    058     * Construct object from input stream.
    059     *
    060     * @param name_index Index of name
    061     * @param length Content length in bytes
    062     * @param input Input stream
    063     * @param constant_pool Array of constants
    064     * @throws IOException
    065     */
    066    StackMap(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    067        this(name_index, length, (StackMapEntry[]) null, constant_pool);
    068        final int map_length = input.readUnsignedShort();
    069        map = new StackMapEntry[map_length];
    070        for (int i = 0; i < map_length; i++) {
    071            map[i] = new StackMapEntry(input, constant_pool);
    072        }
    073    }
    074
    075
    076    /**
    077     * Dump stack map table attribute to file stream in binary format.
    078     *
    079     * @param file Output file stream
    080     * @throws IOException
    081     */
    082    @Override
    083    public final void dump( final DataOutputStream file ) throws IOException {
    084        super.dump(file);
    085        file.writeShort(map.length);
    086        for (final StackMapEntry entry : map) {
    087            entry.dump(file);
    088        }
    089    }
    090
    091
    092    /**
    093     * @return Array of stack map entries
    094     */
    095    public final StackMapEntry[] getStackMap() {
    096        return map;
    097    }
    098
    099
    100    /**
    101     * @param map Array of stack map entries
    102     */
    103    public final void setStackMap( final StackMapEntry[] map ) {
    104        this.map = map;
    105        int len = 2; // Length of 'number_of_entries' field prior to the array of stack maps
    106        for (final StackMapEntry element : map) {
    107            len += element.getMapEntrySize();
    108        }
    109        setLength(len);
    110    }
    111
    112
    113    /**
    114     * @return String representation.
    115     */
    116    @Override
    117    public final String toString() {
    118        final StringBuilder buf = new StringBuilder("StackMap(");
    119        for (int i = 0; i < map.length; i++) {
    120            buf.append(map[i]);
    121            if (i < map.length - 1) {
    122                buf.append(", ");
    123            }
    124        }
    125        buf.append(')');
    126        return buf.toString();
    127    }
    128
    129
    130    /**
    131     * @return deep copy of this attribute
    132     */
    133    @Override
    134    public Attribute copy( final ConstantPool _constant_pool ) {
    135        final StackMap c = (StackMap) clone();
    136        c.map = new StackMapEntry[map.length];
    137        for (int i = 0; i < map.length; i++) {
    138            c.map[i] = map[i].copy();
    139        }
    140        c.setConstantPool(_constant_pool);
    141        return c;
    142    }
    143
    144
    145    /**
    146     * Called by objects that are traversing the nodes of the tree implicitely
    147     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    148     * fields, attributes, etc. spawns a tree of objects.
    149     *
    150     * @param v Visitor object
    151     */
    152    @Override
    153    public void accept( final Visitor v ) {
    154        v.visitStackMap(this);
    155    }
    156
    157
    158    public final int getMapLength() {
    159        return map == null ? 0 : map.length;
    160    }
    161}