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JWKTL (Java Wiktionary Library) is a Java-based API that enables efficient and structured access to the information encoded in the English and the German Wiktionary edition, including sense definitions, part of speech tags, etymology, example sentences, translations, semantic relations and many other lexical information types.

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/*******************************************************************************
 * Copyright 2015
 * Ubiquitous Knowledge Processing (UKP) Lab
 * Technische Universität Darmstadt
 *
 * Licensed 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 de.tudarmstadt.ukp.jwktl.parser;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import org.apache.tools.bzip2.CBZip2InputStream;

/**
 * An input stream which keeps decompressing data from the file / stream until
 * it hits EOF. Useful for decoding files which contain multiple bz2 streams.
 */
class ChainedCBZip2InputStream extends InputStream {
	private final InputStream underlying;
	private InputStream currentBZ2Stream;

	public ChainedCBZip2InputStream(File input) throws FileNotFoundException {
		this(new BufferedInputStream(new FileInputStream(input)));
	}

	public ChainedCBZip2InputStream(InputStream input) throws FileNotFoundException {
		this.underlying = input;
	}

	@Override
	public int read() throws IOException {
		if (currentBZ2Stream == null) {
			final byte[] header = new byte[2];
			final int headerBytes = underlying.read(header);
			if (headerBytes == -1) {
				return -1;
			} else if (headerBytes != 2) {
				throw new IOException("could not read header");
			} else if (header[0] != 'B' || header[1] != 'Z') {
				throw new IOException("invalid bz2 header");
			}
			currentBZ2Stream = new CBZip2InputStream(underlying);
		}

		final int read = currentBZ2Stream.read();
		if (read == -1) {
			currentBZ2Stream = null;
			return read();
		} else {
			return read;
		}
	}

	@Override
	public void close() throws IOException {
		underlying.close();
	}
}