org.apache.uima.lucas.indexer.analysis.TokenStreamConcatenator.java Source code

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Here is the source code for org.apache.uima.lucas.indexer.analysis.TokenStreamConcatenator.java

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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.uima.lucas.indexer.analysis;

import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;

import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenStream;

/**
 * A TokenStreamStringConcatenator takes a {@link java.util.Collection Collection} of
 * {@link org.apache.lucene.analysis.TokenStream tokenstreams} and concats them.
 */
public class TokenStreamConcatenator extends TokenStream {

    private Collection<TokenStream> tokenStreams;

    private Iterator<TokenStream> tokenStreamIterator;

    private TokenStream currentTokenStream;

    public TokenStreamConcatenator(Collection<TokenStream> tokenStreams) {
        super();
        this.tokenStreams = tokenStreams;
        this.tokenStreamIterator = tokenStreams.iterator();

        if (tokenStreamIterator.hasNext())
            currentTokenStream = tokenStreamIterator.next();
    }

    @Override
    public Token next(Token inputToken) throws IOException {
        if (currentTokenStream == null)
            if (tokenStreamIterator.hasNext())
                currentTokenStream = tokenStreamIterator.next();
            else
                return null;

        Token nextToken = currentTokenStream.next(inputToken);
        while (nextToken == null) {
            if (tokenStreamIterator.hasNext()) {
                currentTokenStream = tokenStreamIterator.next();
                nextToken = currentTokenStream.next(inputToken);
            } else
                return null;
        }

        return nextToken;
    }

    public void reset() throws IOException {
        for (TokenStream tokenStream : tokenStreams)
            tokenStream.reset();

        tokenStreamIterator = tokenStreams.iterator();

        if (tokenStreamIterator.hasNext())
            currentTokenStream = tokenStreamIterator.next();
        else
            currentTokenStream = null;
    }

}