001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.commons.compress.harmony.unpack200.bytecode;
020
021import java.io.DataOutputStream;
022import java.io.IOException;
023import java.util.Objects;
024
025/**
026 * An {@link Attribute} representing a constant.
027 */
028public class ConstantValueAttribute extends Attribute {
029
030    private static CPUTF8 attributeName;
031
032    public static void setAttributeName(final CPUTF8 cpUTF8Value) {
033        attributeName = cpUTF8Value;
034    }
035
036    private int constantIndex;
037
038    private final ClassFileEntry entry;
039
040    /**
041     * Constructs a new instance.
042     *
043     * @param entry an entry.
044     */
045    public ConstantValueAttribute(final ClassFileEntry entry) {
046        super(attributeName);
047        this.entry = Objects.requireNonNull(entry, "entry");
048    }
049
050    @Override
051    public boolean equals(final Object obj) {
052        if (this == obj) {
053            return true;
054        }
055        if (!super.equals(obj) || this.getClass() != obj.getClass()) {
056            return false;
057        }
058        final ConstantValueAttribute other = (ConstantValueAttribute) obj;
059        return Objects.equals(entry, other.entry);
060    }
061
062    @Override
063    protected int getLength() {
064        return 2;
065    }
066
067    @Override
068    protected ClassFileEntry[] getNestedClassFileEntries() {
069        return new ClassFileEntry[] { getAttributeName(), entry };
070    }
071
072    @Override
073    public int hashCode() {
074        final int PRIME = 31;
075        int result = super.hashCode();
076        result = PRIME * result + (entry == null ? 0 : entry.hashCode());
077        return result;
078    }
079
080    @Override
081    protected void resolve(final ClassConstantPool pool) {
082        super.resolve(pool);
083        entry.resolve(pool);
084        this.constantIndex = pool.indexOf(entry);
085    }
086
087    @Override
088    public String toString() {
089        return "Constant:" + entry;
090    }
091
092    @Override
093    protected void writeBody(final DataOutputStream dos) throws IOException {
094        dos.writeShort(constantIndex);
095    }
096
097}