content: /*
   * 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.calcite.adapter.enumerable;
  
  import org.apache.calcite.plan.Convention;
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.convert.ConverterRule;
  import org.apache.calcite.rel.core.Project;
  import org.apache.calcite.rel.logical.LogicalProject;
  import org.apache.calcite.rex.RexUtil;
  
  /**
   * Rule to convert a {@link LogicalProject} to an {@link EnumerableProject}.
   * You may provide a custom config to convert other nodes that extend {@link Project}.
   *
   * @see EnumerableRules#ENUMERABLE_PROJECT_RULE
   */
  class EnumerableProjectRule extends ConverterRule {
    /** Default configuration. */
    static final Config DEFAULT_CONFIG = Config.INSTANCE
        .as(Config.class)
        .withConversion(LogicalProject.class, p ->
                !p.containsOver()
                    && !RexUtil.M2V_FINDER.inProject(p)
                    && !RexUtil.SubQueryFinder.containsSubQuery(p),
            Convention.NONE, EnumerableConvention.INSTANCE,
            "EnumerableProjectRule")
        .withRuleFactory(EnumerableProjectRule::new);
  
    /** Creates an EnumerableProjectRule. */
    protected EnumerableProjectRule(Config config) {
      super(config);
    }
  
    @Override public boolean matches(RelOptRuleCall call) {
      Project project = call.rel(0);
      return project.getVariablesSet().isEmpty();
    }
  
    @Override public RelNode convert(RelNode rel) {
      final Project project = (Project) rel;
      return EnumerableProject.create(
          convert(project.getInput(),
              project.getInput().getTraitSet()
                  .replace(EnumerableConvention.INSTANCE)),
          project.getProjects(),
          project.getRowType());
    }
  }
  