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