com.sindicetech.siren.qparser.keyword.processors.PhraseQueryNodeProcessor.java Source code

Introduction

Here is the source code for com.sindicetech.siren.qparser.keyword.processors.PhraseQueryNodeProcessor.java

Source

/**
 * Copyright (c) 2014, Sindice Limited. All Rights Reserved.
 *
 * This file is part of the SIREn project.
 *
 * SIREn is a free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * SIREn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package com.sindicetech.siren.qparser.keyword.processors;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CachingTokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.nodes.*;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.standard.nodes.RegexpQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.WildcardQueryNode;
import org.apache.lucene.util.Version;

import com.sindicetech.siren.qparser.keyword.nodes.DatatypeQueryNode;
import com.sindicetech.siren.qparser.keyword.nodes.ProtectedQueryNode;

import java.io.IOException;
import java.io.StringReader;
import java.util.List;

/**
 * This processor analyses a {@link FieldQueryNode} using a {@link WhitespaceAnalyzer}
 * and outputs a {@link TokenizedPhraseQueryNode} if more than one token are returned.
 *
 * <p>
 *
 * This processor operates on every {@link FieldQueryNode} that is not
 * {@link WildcardQueryNode}, {@link FuzzyQueryNode} or
 * {@link RangeQueryNode} contained in the query node tree, and it applies
 * a {@link WhitespaceAnalyzer} to that {@link FieldQueryNode} object.
 *
 * <p>
 *
 * If the analyzer returns only one term, the node is returned unchanged.
 *
 * <p>
 *
 * If the analyzer returns more than one term, a {@link TokenizedPhraseQueryNode}
 * is created and returned.
 *
 * <p>
 *
 * If no term is returned by the analyzer, a {@link NoTokenFoundQueryNode} object
 * is returned.
 */
public class PhraseQueryNodeProcessor extends QueryNodeProcessorImpl {

    private final Analyzer analyzer = new WhitespaceAnalyzer(Version.LUCENE_46);

    @Override
    protected QueryNode postProcessNode(final QueryNode node) throws QueryNodeException {
        if (node instanceof TextableQueryNode && !(node instanceof WildcardQueryNode)
                && !(node instanceof FuzzyQueryNode) && !(node instanceof RegexpQueryNode)
                && !(node instanceof ProtectedQueryNode) && !(node.getParent() instanceof RangeQueryNode)) {

            final FieldQueryNode fieldNode = ((FieldQueryNode) node);
            final String text = fieldNode.getTextAsString();
            final String field = fieldNode.getFieldAsString();

            final TokenStream source;
            try {
                source = this.analyzer.tokenStream(field, new StringReader(text));
                source.reset();
            } catch (final IOException e1) {
                throw new RuntimeException(e1);
            }
            final CachingTokenFilter buffer = new CachingTokenFilter(source);

            int numTokens = 0;
            try {
                while (buffer.incrementToken()) {
                    numTokens++;
                }
            } catch (final IOException e) {
                // ignore
            }

            try {
                // rewind the buffer stream
                buffer.reset();
                // close original stream - all tokens buffered
                source.close();
            } catch (final IOException e) {
                // ignore
            }

            if (!buffer.hasAttribute(CharTermAttribute.class)) {
                return new NoTokenFoundQueryNode();
            }
            final CharTermAttribute termAtt = buffer.getAttribute(CharTermAttribute.class);

            if (numTokens == 0) {
                return new NoTokenFoundQueryNode();
            }
            // phrase query
            else if (numTokens != 1) {
                String datatype = (String) DatatypeProcessor.getDatatype(this.getQueryConfigHandler(), node);
                final TokenizedPhraseQueryNode pq = new TokenizedPhraseQueryNode();
                // assign datatype
                pq.setTag(DatatypeQueryNode.DATATYPE_TAGID, datatype);

                for (int i = 0; i < numTokens; i++) {
                    String term = null;

                    try {
                        final boolean hasNext = buffer.incrementToken();
                        assert hasNext == true;
                        term = termAtt.toString();

                    } catch (final IOException e) {
                        // safe to ignore, because we know the number of tokens
                    }

                    final FieldQueryNode newFieldNode = new FieldQueryNode(field, term, -1, -1);
                    // set position increment
                    newFieldNode.setPositionIncrement(i);
                    // assign datatype
                    newFieldNode.setTag(DatatypeQueryNode.DATATYPE_TAGID, datatype);
                    pq.add(newFieldNode);
                }
                return pq;
            }
        }
        return node;
    }

    @Override
    protected QueryNode preProcessNode(final QueryNode node) throws QueryNodeException {
        return node;
    }

    @Override
    protected List<QueryNode> setChildrenOrder(final List<QueryNode> children) throws QueryNodeException {
        return children;
    }

}