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;
021import java.util.Objects;
022
023/**
024 * An {@link Attribute} representing a constant.
025 */
026public class ConstantValueAttribute extends Attribute {
027
028    private static CPUTF8 attributeName;
029
030    public static void setAttributeName(final CPUTF8 cpUTF8Value) {
031        attributeName = cpUTF8Value;
032    }
033
034    private int constantIndex;
035
036    private final ClassFileEntry entry;
037
038    public ConstantValueAttribute(final ClassFileEntry entry) {
039        super(attributeName);
040        this.entry = Objects.requireNonNull(entry, "entry");
041    }
042
043    @Override
044    public boolean equals(final Object obj) {
045        if (this == obj) {
046            return true;
047        }
048        if (!super.equals(obj)) {
049            return false;
050        }
051        if (this.getClass() != obj.getClass()) {
052            return false;
053        }
054        final ConstantValueAttribute other = (ConstantValueAttribute) obj;
055        return Objects.equals(entry, other.entry);
056    }
057
058    @Override
059    protected int getLength() {
060        return 2;
061    }
062
063    @Override
064    protected ClassFileEntry[] getNestedClassFileEntries() {
065        return new ClassFileEntry[] { getAttributeName(), entry };
066    }
067
068    @Override
069    public int hashCode() {
070        final int PRIME = 31;
071        int result = super.hashCode();
072        result = PRIME * result + (entry == null ? 0 : entry.hashCode());
073        return result;
074    }
075
076    @Override
077    protected void resolve(final ClassConstantPool pool) {
078        super.resolve(pool);
079        entry.resolve(pool);
080        this.constantIndex = pool.indexOf(entry);
081    }
082
083    @Override
084    public String toString() {
085        return "Constant:" + entry;
086    }
087
088    @Override
089    protected void writeBody(final DataOutputStream dos) throws IOException {
090        dos.writeShort(constantIndex);
091    }
092
093}