com.qwazr.search.query.SpanPositionsQuery.java Source code

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Here is the source code for com.qwazr.search.query.SpanPositionsQuery.java

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/**
 * Copyright 2015-2016 Emmanuel Keller / QWAZR
 * <p>
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.qwazr.search.query;

import com.qwazr.search.index.QueryContext;
import com.qwazr.utils.IOUtils;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.BoostQuery;
import org.apache.lucene.search.spans.SpanPositionRangeQuery;
import org.apache.lucene.search.spans.SpanTermQuery;

import java.io.IOException;

public class SpanPositionsQuery extends AbstractQuery {

    final public String field;
    final public Integer distance;

    public SpanPositionsQuery() {
        field = null;
        distance = null;
    }

    public SpanPositionsQuery(String field, Integer distance) {
        this.field = field;
        this.distance = distance;
    }

    @Override
    final public Query getQuery(QueryContext queryContext) throws IOException {

        BooleanQuery.Builder builder = new BooleanQuery.Builder();
        TokenStream tokenStream = queryContext.analyzer.tokenStream(field, queryContext.queryString);
        try {
            CharTermAttribute charTermAttribute = tokenStream.getAttribute(CharTermAttribute.class);
            PositionIncrementAttribute pocincrAttribute = tokenStream
                    .getAttribute(PositionIncrementAttribute.class);
            tokenStream.reset();
            int pos = 0;
            while (tokenStream.incrementToken()) {
                final String charTerm = charTermAttribute.toString();
                int start = pos - distance;
                if (start < 0)
                    start = 0;
                final int end = pos + distance + 1;
                for (int i = start; i < end; i++) {
                    final float dist = Math.abs(i - pos) + 1;
                    final float boost = 1 / dist;
                    final SpanTermQuery spanTermQuery = new SpanTermQuery(new Term(field, charTerm));
                    Query query = new BoostQuery(new SpanPositionRangeQuery(spanTermQuery, i, i + 1), boost);
                    builder.add(new BooleanClause(query, BooleanClause.Occur.SHOULD));
                }
                pos += pocincrAttribute.getPositionIncrement();
            }
            return builder.build();
        } finally {
            IOUtils.closeQuietly(tokenStream);
        }
    }

}