ch.sentric.hbase.prospective.Percolator.java Source code

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Here is the source code for ch.sentric.hbase.prospective.Percolator.java

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/**
 * Copyright 2012 Sentric AG
 *
 * 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
 *
 *     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 ch.sentric.hbase.prospective;

import java.io.IOException;
import java.io.Reader;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.io.input.CharSequenceReader;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Fieldable;
import org.apache.lucene.index.memory.MemoryIndex;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;

/**
 * It uses {@code CustomMemoryIndex} a fast RAM-only index to test whether a
 * single document matches a set of queries.
 * 
 * @param <T>
 *            the generic ID type
 * 
 */
public class Percolator<T> {
    public static final Log LOG = LogFactory.getLog(Percolator.class);
    private final Analyzer analyzer;

    /**
     * Create a {@code Percolator} instance with the given {@code Analyzer}.
     * 
     * @param analyzer
     *            to find terms in the text and queries
     * @param queries
     *            the parsed queries
     */

    public Percolator(final Analyzer analyzer) {
        this.analyzer = analyzer;
        if (LOG.isDebugEnabled()) {
            LOG.debug("Percolator initialized.");
        }
    }

    /**
    * Tries to find a set of queries that match the given document.
    * 
    * @param doc
    *            the Lucene document
    * @return the matching queries
    * @throws IOException
    *             if an I/O error occurs
    */
    public Response<T> percolate(final Document doc, final Map<T, Query> queries) throws IOException {
        // first, parse the source doc into a MemoryIndex
        final MemoryIndex memoryIndex = new MemoryIndex();

        for (final Fieldable field : doc.getFields()) {
            if (!field.isIndexed()) {
                continue;
            }

            final TokenStream tokenStream = field.tokenStreamValue();
            if (tokenStream != null) {
                memoryIndex.addField(field.name(), tokenStream, field.getBoost());
            } else {
                final Reader reader = field.readerValue();
                if (reader != null) {
                    memoryIndex.addField(field.name(), analyzer.reusableTokenStream(field.name(), reader),
                            field.getBoost());
                } else {
                    final String value = field.stringValue();
                    if (value != null) {
                        memoryIndex.addField(field.name(),
                                analyzer.reusableTokenStream(field.name(), new CharSequenceReader(value)),
                                field.getBoost());
                    }
                }
            }
        }

        // do the search
        final IndexSearcher searcher = memoryIndex.createSearcher();
        final Map<T, Query> matches = new HashMap<T, Query>(0);

        if (queries != null && !queries.isEmpty()) {
            final ExistsCollector collector = new ExistsCollector();
            for (final Map.Entry<T, Query> entry : queries.entrySet()) {
                collector.reset();
                searcher.search(entry.getValue(), collector);
                if (collector.exists()) {
                    matches.put(entry.getKey(), entry.getValue());
                }
            }
        }

        return new Response<T>(matches);
    }
}