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.schema.lookup;
  
  import org.apache.calcite.linq4j.function.Predicate1;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.Set;
  import java.util.function.Function;
  import java.util.function.Supplier;
  import java.util.stream.Collectors;
  
  /**
   * This class warps a {@code Function} and a {@code Supplier} into a
   * {@code Lookup} interface.
   *
   * <p>This class can be used to implement the methods {@code Schema.tables()}
   * and {@code Schema.subSchemas()} of existing schemas.
   *
   * <p>Existing schema classes are implementing a pair of {@code getTable()}
   * and {@code getTableNames()} methods. But these schemas should
   * also provide a {@code tables()} method. This class can be used
   * to implement this method. See {@code Schema.tables()} for
   * an example.
   *
   * @param <T> Element type
   */
  public class CompatibilityLookup<T> extends IgnoreCaseLookup<T> {
  
    private final Function<String, @Nullable T> get;
    private final Supplier<Set<String>> getNames;
  
    /**
     * Constructor to create a {@code Lookup} instance using a `Function` and a `Supplier`.
     *
     * @param get a function to lookup tables or sub schemas by name
     * @param getNames a function to list all tables or sub schemas
     */
    public CompatibilityLookup(Function<String, @Nullable T> get, Supplier<Set<String>> getNames) {
      this.get = get;
      this.getNames = getNames;
    }
  
    @Override public @Nullable T get(String name) {
      return get.apply(name);
    }
  
    @Override public Set<String> getNames(LikePattern pattern) {
      final Predicate1<String> matcher = pattern.matcher();
      return getNames.get().stream()
          .filter(name -> matcher.apply(name))
          .collect(Collectors.toSet());
    }
  }
  