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.model;
  
  import com.fasterxml.jackson.annotation.JsonSubTypes;
  import com.fasterxml.jackson.annotation.JsonTypeInfo;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Schema schema element.
   *
   * <p>Occurs within {@link JsonRoot#schemas}.
   *
   * @see JsonRoot Description of schema elements
   */
  @JsonTypeInfo(
      use = JsonTypeInfo.Id.NAME,
      property = "type",
      defaultImpl = JsonMapSchema.class)
  @JsonSubTypes({
      @JsonSubTypes.Type(value = JsonMapSchema.class, name = "map"),
      @JsonSubTypes.Type(value = JsonJdbcSchema.class, name = "jdbc"),
      @JsonSubTypes.Type(value = JsonCustomSchema.class, name = "custom") })
  public abstract class JsonSchema {
    /** Name of the schema.
     *
     * <p>Required.
     *
     * @see JsonRoot#defaultSchema
     */
    public final String name;
  
    /** SQL path that is used to resolve functions used in this schema.
     *
     * <p>May be null, or a list, each element of which is a string or a
     * string-list.
     *
     * <p>For example,
     *
     * <blockquote><pre>path: [ ['usr', 'lib'], 'lib' ]</pre></blockquote>
     *
     * <p>declares a path with two elements: the schema '/usr/lib' and the schema
     * '/lib'. Most schemas are at the top level, and for these you can use a
     * string.
     */
    public final @Nullable List<Object> path;
  
    /**
     * List of tables in this schema that are materializations of queries.
     *
     * <p>The list may be empty.
     */
    public final List<JsonMaterialization> materializations = new ArrayList<>();
  
    public final List<JsonLattice> lattices = new ArrayList<>();
  
    /** Whether to cache metadata (tables, functions and sub-schemas) generated
     * by this schema. Default value is {@code true}.
     *
     * <p>If {@code false}, Calcite will go back to the schema each time it needs
     * metadata, for example, each time it needs a list of tables in order to
     * validate a query against the schema.
     *
     * <p>If {@code true}, Calcite will cache the metadata the first time it reads
     * it. This can lead to better performance, especially if name-matching is
     * case-insensitive
     * (see {@link org.apache.calcite.config.Lex#caseSensitive}).
     *
     * <p>Tables, functions and sub-schemas explicitly created in a schema are
     * not affected by this caching mechanism. They always appear in the schema
     * immediately, and are never flushed.
     */
    public final @Nullable Boolean cache;
  
    /** Whether to create lattices in this schema based on queries occurring in
     * other schemas. Default value is {@code false}. */
    public final @Nullable Boolean autoLattice;
  
    protected JsonSchema(String name, @Nullable List<Object> path, @Nullable Boolean cache,
        @Nullable Boolean autoLattice) {
      this.name = name;
      this.path = path;
      this.cache = cache;
      this.autoLattice = autoLattice;
    }
  
    public abstract void accept(ModelHandler handler);
  
    public void visitChildren(ModelHandler modelHandler) {
      for (JsonLattice jsonLattice : lattices) {
        jsonLattice.accept(modelHandler);
      }
      for (JsonMaterialization jsonMaterialization : materializations) {
        jsonMaterialization.accept(modelHandler);
      }
    }
  
    /** Built-in schema types. */
    public enum Type {
      MAP,
      JDBC,
      CUSTOM
    }
  }
  