org.hibernate.search.indexes.serialization.impl.CopyTokenStream.java Source code

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Here is the source code for org.hibernate.search.indexes.serialization.impl.CopyTokenStream.java

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * JBoss, Home of Professional Open Source
 * Copyright 2011 Red Hat Inc. and/or its affiliates and other contributors
 * as indicated by the @authors tag. All rights reserved.
 * See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License, v. 2.1.
 * This program is distributed in the hope that it will be useful, but WITHOUT A
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 * You should have received a copy of the GNU Lesser General Public License,
 * v.2.1 along with this distribution; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA  02110-1301, USA.
 */
package org.hibernate.search.indexes.serialization.impl;

import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.util.AttributeImpl;

import org.hibernate.search.indexes.serialization.spi.SerializableTokenStream;
import org.hibernate.search.util.logging.impl.Log;
import org.hibernate.search.util.logging.impl.LoggerFactory;

/**
 * Copy all AttributeImpl for each incrementToken
 *
 * Inspired by org.apache.lucene.analysis.CachingTokenFilter
 * Original file released under the ASL 2.0 license
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * @author Emmanuel Bernard <emmanuel@hibernate.org>
 */
public class CopyTokenStream extends TokenStream implements Serializable {
    private static final Log log = LoggerFactory.make();

    private List<List<AttributeImpl>> cache;
    private int index;

    public static SerializableTokenStream buildSerializabletokenStream(TokenStream tokenStream) {
        try {
            List<List<AttributeImpl>> stream = fillCache(tokenStream);
            return new SerializableTokenStream(stream);
        } catch (IOException e) {
            throw log.unableToReadTokenStream();
        }
    }

    public CopyTokenStream(List<List<AttributeImpl>> stream) {
        this.index = 0;
        this.cache = stream;
    }

    @Override
    public final boolean incrementToken() throws IOException {
        if (index >= cache.size()) {
            // the cache is exhausted, return false
            return false;
        }

        // Since the TokenFilter can be reset, the tokens need to be preserved as immutable.
        setState(index);
        index++;
        return true;
    }

    private void setState(int localIndex) {
        for (AttributeImpl attr : cache.get(localIndex)) {
            addAttributeImpl(attr);
        }
    }

    @Override
    public final void end() throws IOException {
        if (cache.size() > 0) {
            setState(cache.size() - 1);
        }
    }

    @Override
    public void reset() throws IOException {
        index = 0;
    }

    private static List<List<AttributeImpl>> fillCache(TokenStream input) throws IOException {
        List<List<AttributeImpl>> results = new ArrayList<List<AttributeImpl>>();
        while (input.incrementToken()) {
            List<AttributeImpl> attrs = new ArrayList<AttributeImpl>();
            results.add(attrs);
            Iterator<AttributeImpl> iter = input.getAttributeImplsIterator();
            while (iter.hasNext()) {
                //we need to clone as AttributeImpl instances can be reused across incrementToken() calls
                attrs.add((AttributeImpl) iter.next().clone());
            }
        }
        input.end();
        return results;
    }
}