io.prestosql.sql.planner.iterative.rule.PruneUnnestSourceColumns Maven / Gradle / Ivy

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/*
 * 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 io.prestosql.sql.planner.iterative.rule;

import com.google.common.collect.ImmutableSet;
import io.prestosql.matching.Captures;
import io.prestosql.matching.Pattern;
import io.prestosql.sql.planner.Symbol;
import io.prestosql.sql.planner.iterative.Rule;
import io.prestosql.sql.planner.plan.UnnestNode;

import static io.prestosql.sql.planner.iterative.rule.Util.restrictChildOutputs;
import static io.prestosql.sql.planner.plan.Patterns.unnest;

public class PruneUnnestSourceColumns
        implements Rule
{
    @Override
    public Pattern getPattern()
    {
        return unnest();
    }

    @Override
    public Result apply(UnnestNode node, Captures captures, Context context)
    {
        ImmutableSet.Builder expectedInputs = ImmutableSet.builder()
                .addAll(node.getReplicateSymbols());
        node.getMappings().stream()
                .map(UnnestNode.Mapping::getInput)
                .forEach(expectedInputs::add);

        return restrictChildOutputs(context.getIdAllocator(), node, expectedInputs.build())
                .map(Result::ofPlanNode)
                .orElse(Result.empty());
    }
}