org.apache.lucene.analysis.CannedTokenStream.java Source code

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Here is the source code for org.apache.lucene.analysis.CannedTokenStream.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.lucene.analysis;

import java.io.IOException;

import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;

/**
 * TokenStream from a canned list of Tokens.
 */
public final class CannedTokenStream extends TokenStream {
    private final Token[] tokens;
    private int upto = 0;
    private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
    private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class);
    private final int finalOffset;
    private final int finalPosInc;

    public CannedTokenStream(Token... tokens) {
        this(0, 0, tokens);
    }

    /** If you want trailing holes, pass a non-zero
     *  finalPosInc. */
    public CannedTokenStream(int finalPosInc, int finalOffset, Token... tokens) {
        super(Token.TOKEN_ATTRIBUTE_FACTORY);
        this.tokens = tokens;
        this.finalOffset = finalOffset;
        this.finalPosInc = finalPosInc;
    }

    @Override
    public void end() throws IOException {
        super.end();
        posIncrAtt.setPositionIncrement(finalPosInc);
        offsetAtt.setOffset(finalOffset, finalOffset);
    }

    @Override
    public void reset() throws IOException {
        upto = 0;
        super.reset();
    }

    @Override
    public boolean incrementToken() {
        if (upto < tokens.length) {
            clearAttributes();
            // NOTE: this looks weird, casting offsetAtt to Token, but because we are using the Token class's AttributeFactory, all attributes are
            // in fact backed by the Token class, so we just copy the current token into our Token:
            tokens[upto++].copyTo((Token) offsetAtt);
            return true;
        } else {
            return false;
        }
    }
}