com.twitter.common.text.token.TokenStream2LuceneTokenizerWrapper.java Source code

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Here is the source code for com.twitter.common.text.token.TokenStream2LuceneTokenizerWrapper.java

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// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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 com.twitter.common.text.token;

import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;

import org.apache.commons.io.IOUtils;
import org.apache.lucene.analysis.Tokenizer;

import com.google.common.base.Preconditions;

/**
 * Converts a {@link TokenStream} instance to a Lucene's {@code Tokenizer} instance.
 */
public class TokenStream2LuceneTokenizerWrapper extends Tokenizer {
    private final TokenStream stream;

    public TokenStream2LuceneTokenizerWrapper(TokenStream stream, Reader input) throws IOException {
        super(stream.cloneAttributes());
        this.stream = stream;
        reset(input);
    }

    @Override
    public boolean incrementToken() throws IOException {
        if (!stream.incrementToken()) {
            return false;
        }
        clearAttributes();
        restoreState(stream.captureState());
        return true;
    }

    @Override
    public void reset(Reader input) throws IOException {
        Preconditions.checkNotNull(input);
        StringWriter writer = new StringWriter();
        IOUtils.copy(input, writer);
        stream.reset(writer.toString());
    }
}