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.commons.compress.harmony.unpack200.bytecode;
018
019import java.io.DataOutputStream;
020import java.io.IOException;
021
022/**
023 * Abstract superclass for class file attributes
024 */
025public abstract class Attribute extends ClassFileEntry {
026
027    protected final CPUTF8 attributeName;
028
029    private int attributeNameIndex;
030
031    public Attribute(final CPUTF8 attributeName) {
032        this.attributeName = attributeName;
033    }
034
035    @Override
036    protected void doWrite(final DataOutputStream dos) throws IOException {
037        dos.writeShort(attributeNameIndex);
038        dos.writeInt(getLength());
039        writeBody(dos);
040    }
041
042    @Override
043    public boolean equals(final Object obj) {
044        if (this == obj) {
045            return true;
046        }
047        if (obj == null) {
048            return false;
049        }
050        if (this.getClass() != obj.getClass()) {
051            return false;
052        }
053        final Attribute other = (Attribute) obj;
054        if (attributeName == null) {
055            if (other.attributeName != null) {
056                return false;
057            }
058        } else if (!attributeName.equals(other.attributeName)) {
059            return false;
060        }
061        return true;
062    }
063
064    protected CPUTF8 getAttributeName() {
065        return attributeName;
066    }
067
068    protected abstract int getLength();
069
070    /**
071     * Answer the length of the receiver including its header (the u2 for the attribute name and the u4 for the
072     * attribute length). This is relevant when attributes are nested within other attributes - the outer attribute
073     * needs to take the inner attribute headers into account when calculating its length.
074     *
075     * @return int adjusted length
076     */
077    protected int getLengthIncludingHeader() {
078        return getLength() + 2 + 4;
079    }
080
081    @Override
082    protected ClassFileEntry[] getNestedClassFileEntries() {
083        return new ClassFileEntry[] {getAttributeName()};
084    }
085
086    /**
087     * Answer true if the receiver needs to have BCI renumbering applied to it; otherwise answer false.
088     *
089     * @return boolean BCI renumbering required
090     */
091    public boolean hasBCIRenumbering() {
092        return false;
093    }
094
095    /**
096     * Answer true if the receiver is a source file attribute (which gets special handling when the class is built);
097     * otherwise answer false.
098     *
099     * @return boolean source file attribute
100     */
101    public boolean isSourceFileAttribute() {
102        return false;
103    }
104
105    @Override
106    public int hashCode() {
107        final int PRIME = 31;
108        int result = 1;
109        result = PRIME * result + ((attributeName == null) ? 0 : attributeName.hashCode());
110        return result;
111    }
112
113    @Override
114    protected void resolve(final ClassConstantPool pool) {
115        super.resolve(pool);
116        attributeNameIndex = pool.indexOf(attributeName);
117    }
118
119    protected abstract void writeBody(DataOutputStream dos) throws IOException;
120
121}