OneRowRelationToProject.java

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//
//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.nereids.rules.analysis;

import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.trees.expressions.Alias;
import org.apache.doris.nereids.trees.expressions.literal.TinyIntLiteral;
import org.apache.doris.nereids.trees.plans.logical.LogicalOneRowRelation;
import org.apache.doris.nereids.trees.plans.logical.LogicalProject;

import com.google.common.collect.ImmutableList;

/**
 * LogicalOneRowRelation -> LogicalProject(LogicalOneRowRelation)
 */
public class OneRowRelationToProject extends OneAnalysisRuleFactory {
    @Override
    public Rule build() {
        return RuleType.ONE_ROW_RELATION_TO_PROJECT.build(
            logicalOneRowRelation().whenNot(LogicalOneRowRelation::isValid).then(oneRow ->
                new LogicalProject<>(
                    oneRow.getProjects(),
                    new LogicalOneRowRelation(
                        oneRow.getRelationId(),
                        ImmutableList.of(new Alias(new TinyIntLiteral((byte) 1)))
                    )
                )
            )
        );
    }
}