fr.inria.oak.paxquery.pact.operators.unary.NavigationOperator.java Source code

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/*******************************************************************************
 * Copyright (C) 2013, 2014, 2015 by Inria and Paris-Sud University
 * 
 * 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 fr.inria.oak.paxquery.pact.operators.unary;

import java.io.StringReader;
import java.util.Iterator;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.types.Record;
import org.apache.flink.types.StringValue;
import org.apache.flink.util.Collector;

import fr.inria.oak.paxquery.common.datamodel.metadata.NestedMetadata;
import fr.inria.oak.paxquery.common.xml.navigation.NavigationTreePattern;
import fr.inria.oak.paxquery.common.xml.navigation.NavigationTreePatternUtils;
import fr.inria.oak.paxquery.pact.configuration.PACTOperatorsConfiguration;
import fr.inria.oak.paxquery.pact.operations.RecordOperations;
import fr.inria.oak.paxquery.pact.operations.xml.navigation.SingleDocumentExtractor;
import fr.inria.oak.paxquery.pact.operators.BaseMapOperator;

/**
 * Tree pattern navigation operator in PACT.
 * 
 */
public class NavigationOperator extends BaseMapOperator {

    private static final Log logger = LogFactory.getLog(NavigationOperator.class);

    private int column;

    private NavigationTreePattern navigationTreePattern;

    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);

        final int column = parameters.getInteger(PACTOperatorsConfiguration.NAVIGATION_COLUMN_INT.toString(), -1);
        this.column = column;

        final NavigationTreePattern ntp = NavigationTreePatternUtils.getTreePatternFromString(
                parameters.getString(PACTOperatorsConfiguration.NTP_STRING.toString(), null), "queryTest");
        this.navigationTreePattern = ntp;
    }

    @Override
    public void map(Record record, Collector<Record> collector) {
        navigation(this.inputRecordsSignature, record, this.column, this.navigationTreePattern, collector);
    }

    /**
     * 
     * @param record
     * @param treePattern
     * @param collector
     */
    public static void navigation(NestedMetadata inputRecordSignature, Record record, int column,
            NavigationTreePattern navigationTreePattern, Collector<Record> collector) {
        XMLInputFactory factory = XMLInputFactory.newInstance();

        try {
            StringValue value = record.getField(column, StringValue.class);
            XMLStreamReader streamReader = factory.createXMLStreamReader(new StringReader(value.getValue()));

            SingleDocumentExtractor extractor = new SingleDocumentExtractor(navigationTreePattern, streamReader);

            while (streamReader.hasNext()) {
                streamReader.next();
                if (streamReader.getEventType() == XMLStreamConstants.START_ELEMENT) {
                    extractor.startElement();
                } else if (streamReader.getEventType() == XMLStreamConstants.END_ELEMENT) {
                    extractor.endElement();
                } else if (streamReader.getEventType() == XMLStreamConstants.CHARACTERS) {
                    extractor.characters();
                }

                if (extractor.getRecords().size() != 0) {
                    Iterator<Record> pactRecordsIterator = extractor.getRecords().iterator();
                    while (pactRecordsIterator.hasNext()) {
                        Record originalRecord = record.createCopy();
                        RecordOperations.concatenate(originalRecord, pactRecordsIterator.next());
                        collector.collect(originalRecord);
                    }

                    extractor.getRecords().clear();
                }
            }

        } catch (XMLStreamException e) {
            logger.error("XMLStreamException", e);
        }
    }
}