MergeProjectsCBO.java

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package org.apache.doris.nereids.rules.exploration;

import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.rules.rewrite.MergeProjects;

/**
 * this rule aims to merge projects.
 */
public class MergeProjectsCBO extends OneExplorationRuleFactory {
    @Override
    public Rule build() {
        return logicalProject(logicalProject())
                .when(project -> project.canMergeProjections(project.child()))
                .then(project -> MergeProjects.mergeProjects(project))
                .toRule(RuleType.MERGE_PROJECTS);
    }
}