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.plan;
  
  import org.apache.calcite.rel.RelRoot;
  import org.apache.calcite.rel.hint.RelHint;
  import org.apache.calcite.rel.type.RelDataType;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * Utilities for {@link RelOptTable.ViewExpander} and
   * {@link RelOptTable.ToRelContext}.
   */
  public abstract class ViewExpanders {
    private ViewExpanders() {}
  
    /** Converts a {@code ViewExpander} to a {@code ToRelContext}. */
    public static RelOptTable.ToRelContext toRelContext(
        RelOptTable.ViewExpander viewExpander,
        RelOptCluster cluster,
        List<RelHint> hints) {
      return new RelOptTable.ToRelContext() {
        @Override public RelOptCluster getCluster() {
          return cluster;
        }
  
        @Override public List<RelHint> getTableHints() {
          return hints;
        }
  
        @Override public RelRoot expandView(RelDataType rowType, String queryString,
            List<String> schemaPath, @Nullable List<String> viewPath) {
          return viewExpander.expandView(rowType, queryString, schemaPath,
              viewPath);
        }
      };
    }
  
    /** Converts a {@code ViewExpander} to a {@code ToRelContext}. */
    public static RelOptTable.ToRelContext toRelContext(
        RelOptTable.ViewExpander viewExpander,
        RelOptCluster cluster) {
      return toRelContext(viewExpander, cluster, ImmutableList.of());
    }
  
    /** Creates a simple {@code ToRelContext} that cannot expand views. */
    public static RelOptTable.ToRelContext simpleContext(RelOptCluster cluster) {
      return simpleContext(cluster, ImmutableList.of());
    }
  
    /** Creates a simple {@code ToRelContext} that cannot expand views. */
    public static RelOptTable.ToRelContext simpleContext(
        RelOptCluster cluster,
        List<RelHint> hints) {
      return new RelOptTable.ToRelContext() {
        @Override public RelOptCluster getCluster() {
          return cluster;
        }
  
        @Override public RelRoot expandView(RelDataType rowType, String queryString,
            List<String> schemaPath, @Nullable List<String> viewPath) {
          throw new UnsupportedOperationException();
        }
  
        @Override public List<RelHint> getTableHints() {
          return hints;
        }
      };
    }
  }
  