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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.

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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.commons.compress.harmony.pack200;

import org.objectweb.asm.ClassReader;

/**
 * Wrapper for ClassReader that enables pack200 to obtain extra class file information
 */
public class Pack200ClassReader extends ClassReader {

    private boolean lastConstantHadWideIndex;
    private int lastUnsignedShort;
    private boolean anySyntheticAttributes;
    private String fileName;

    /**
     * @param b the contents of class file in the format of bytes
     */
    public Pack200ClassReader(final byte[] b) {
        super(b);
    }

    public String getFileName() {
        return fileName;
    }

    public boolean hasSyntheticAttributes() {
        return anySyntheticAttributes;
    }

    public boolean lastConstantHadWideIndex() {
        return lastConstantHadWideIndex;
    }

    @Override
    public Object readConst(final int item, final char[] buf) {
        lastConstantHadWideIndex = item == lastUnsignedShort;
        return super.readConst(item, buf);
    }

    @Override
    public int readUnsignedShort(final int index) {
        // Doing this to check whether last load-constant instruction was ldc (18) or ldc_w (19)
        // TODO: Assess whether this impacts on performance
        final int unsignedShort = super.readUnsignedShort(index);
        if (index > 0 && b[index - 1] == 19) {
            lastUnsignedShort = unsignedShort;
        } else {
            lastUnsignedShort = Short.MIN_VALUE;
        }
        return unsignedShort;
    }

    @Override
    public String readUTF8(final int arg0, final char[] arg1) {
        final String utf8 = super.readUTF8(arg0, arg1);
        if (!anySyntheticAttributes && "Synthetic".equals(utf8)) {
            anySyntheticAttributes = true;
        }
        return utf8;
    }

    public void setFileName(final String name) {
        this.fileName = name;
    }

}