hazelcast-master/hazelcast-sql/src/main/java/com/hazelcast/jet/sql/impl/opt/physical/RootRel.java
/*
 * Copyright 2023 Hazelcast Inc.
 *
 * Licensed under the Hazelcast Community License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://hazelcast.com/hazelcast-community-license
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.hazelcast.jet.sql.impl.opt.physical;

import com.hazelcast.sql.impl.QueryParameterMetadata;
import com.hazelcast.sql.impl.plan.node.PlanNodeSchema;
import org.apache.calcite.plan.RelOptCost;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.RelWriter;
import org.apache.calcite.rel.SingleRel;
import org.apache.calcite.rel.metadata.RelMetadataQuery;

public class RootRel extends SingleRel implements PhysicalRel {

    public RootRel(RelNode input) {
        super(input.getCluster(), RelTraitSet.createEmpty(), input);
    }

    @Override
    public PlanNodeSchema schema(QueryParameterMetadata parameterMetadata) {
        throw new UnsupportedOperationException();
    }

    @Override
    public <V> V accept(CreateDagVisitor<V> visitor) {
        return visitor.onRoot(this);
    }

    @Override
    public final RelWriter explainTerms(RelWriter pw) {
        return super.explainTerms(pw);
    }

    @Override
    public final RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
        double rows = mq.getRowCount(getInput());
        double cpu = rows;

        return planner.getCostFactory().makeCost(rows, cpu, 0);
    }
}
