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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.flink.optimizer.dag;

import org.apache.flink.api.common.operators.SemanticProperties;
import org.apache.flink.api.common.operators.SingleInputOperator;
import org.apache.flink.api.common.operators.SingleInputSemanticProperties;
import org.apache.flink.api.common.operators.util.FieldSet;
import org.apache.flink.optimizer.DataStatistics;
import org.apache.flink.optimizer.operators.MapPartitionDescriptor;
import org.apache.flink.optimizer.operators.OperatorDescriptorSingle;

import java.util.Collections;
import java.util.List;

/** The optimizer's internal representation of a MapPartition operator node. */
public class MapPartitionNode extends SingleInputNode {

    private final List possibleProperties;

    /**
     * Creates a new MapNode for the given contract.
     *
     * @param operator The map partition contract object.
     */
    public MapPartitionNode(SingleInputOperator operator) {
        super(operator);

        this.possibleProperties =
                Collections.singletonList(new MapPartitionDescriptor());
    }

    @Override
    public String getOperatorName() {
        return "MapPartition";
    }

    @Override
    protected List getPossibleProperties() {
        return this.possibleProperties;
    }

    @Override
    protected SemanticProperties getSemanticPropertiesForLocalPropertyFiltering() {

        // Local properties for MapPartition may not be preserved.
        SingleInputSemanticProperties origProps =
                ((SingleInputOperator) getOperator()).getSemanticProperties();
        SingleInputSemanticProperties filteredProps = new SingleInputSemanticProperties();
        FieldSet readSet = origProps.getReadFields(0);
        if (readSet != null) {
            filteredProps.addReadFields(readSet);
        }

        return filteredProps;
    }

    /**
     * Computes the estimates for the MapPartition operator. We assume that by default, Map takes
     * one value and transforms it into another value. The cardinality consequently stays the same.
     */
    @Override
    protected void computeOperatorSpecificDefaultEstimates(DataStatistics statistics) {
        // we really cannot make any estimates here
    }
}