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 com.datastax.oss.driver.internal.core.metadata.schema.queries;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.util.List;
  
  /**
   * Filters keyspaces during schema metadata queries.
   *
   * <p>Depending on the circumstances, we do it either on the server side with a WHERE IN clause that
   * will be appended to every query, or on the client side with a predicate that will be applied to
   * every fetched row.
   */
  public interface KeyspaceFilter {
  
    static KeyspaceFilter newInstance(@NonNull String logPrefix, @NonNull List<String> specs) {
      if (specs.isEmpty()) {
        return INCLUDE_ALL;
      } else {
        return new RuleBasedKeyspaceFilter(logPrefix, specs);
      }
    }
  
    /** The WHERE IN clause, or an empty string if there is no server-side filtering. */
    @NonNull
    String getWhereClause();
  
    /** The predicate that will be invoked for client-side filtering. */
    boolean includes(@NonNull String keyspace);
  
    KeyspaceFilter INCLUDE_ALL =
        new KeyspaceFilter() {
          @NonNull
          @Override
          public String getWhereClause() {
            return "";
          }
  
          @Override
          public boolean includes(@NonNull String keyspace) {
            return true;
          }
        };
  }
  