fr.inria.oak.paxquery.pact.operations.aggregation.Min.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.operations.aggregation;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.flink.types.StringValue;
import org.apache.flink.types.Value;

import fr.inria.oak.paxquery.common.datamodel.metadata.MetadataTypes;

/**
 * Min aggregation operation.
 *
 */
public class Min extends BaseAggregationOperation {

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

    private final MetadataTypes type;

    private double minDouble;

    private int count;

    public Min(MetadataTypes type) {
        this.type = type;

        switch (this.type) {
        case STRING_TYPE:
            this.minDouble = Double.POSITIVE_INFINITY;
            break;
        default:
            logger.error("Min aggregation not supported for this data type!");
        }

        this.count = 0;
    }

    @Override
    public void aggregate(Value value) {
        switch (this.type) {
        case STRING_TYPE:
            final String stringValue = ((StringValue) value).getValue();
            if (!stringValue.equals("\0")) {
                final double newDouble = Double.parseDouble(stringValue);
                if (newDouble < this.minDouble)
                    this.minDouble = newDouble;
                this.count++;
            }
            break;
        default:
            logger.error("Min aggregation not supported for this data type!");
        }
    }

    @Override
    public Value returnResult() {
        switch (this.type) {
        case STRING_TYPE:
            if (this.count == 0)
                return new StringValue("\0");
            return new StringValue(String.valueOf(this.minDouble));
        default:
            logger.error("Min aggregation not supported for this data type!");
            return null;
        }
    }

    @Override
    public void combineAggregation(Value value) {
        this.aggregate(value);
    }

}