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
   *
   *    https://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.cayenne.query;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.map.DataMap;
  import org.apache.cayenne.map.DbEntity;
  import org.apache.cayenne.map.EntityResolver;
  import org.apache.cayenne.map.ObjEntity;
  import org.apache.cayenne.map.Procedure;
  import org.apache.cayenne.util.ToStringBuilder;
  
  /**
   * A common superclass of Cayenne queries.
   */
  public abstract class AbstractQuery extends CacheableQuery {
  
      /**
       * The root object this query. May be an entity name, Java class, ObjEntity or
       * DbEntity, depending on the specific query and how it was constructed.
       */
      protected Object root;
  
      /**
       * Returns default select parameters.
       * 
       * @since 1.2
       */
      public QueryMetadata getMetaData(EntityResolver resolver) {
          BaseQueryMetadata md = new BaseQueryMetadata();
          md.resolve(getRoot(), resolver);
          return md;
      }
  
      /**
       * Returns the root of this query.
       */
      public Object getRoot() {
          return root;
      }
  
      /**
       * Sets the root of the query
       * 
       * @param value The new root
       * @throws IllegalArgumentException if value is not a String, ObjEntity, DbEntity,
       *             Procedure, DataMap, Class or null.
       */
      public void setRoot(Object value) {
          if (value == null) {
              this.root = null;
          }
  
          // sanity check
          if (!((value instanceof String)
                  || (value instanceof ObjEntity)
                  || (value instanceof DbEntity)
                  || (value instanceof Class)
                  || (value instanceof Procedure) || (value instanceof DataMap))) {
  
              String rootClass = (value != null) ? value.getClass().getName() : "null";
  
              throw new IllegalArgumentException(
                      getClass().getName()
                              + ": \"setRoot(..)\" takes a DataMap, String, ObjEntity, DbEntity, Procedure, "
                              + "or Class. It was passed a "
                              + rootClass);
          }
  
          this.root = value;
      }
  
      @Override
      public String toString() {
          return new ToStringBuilder(this)
                  .append("root", root)
                  .toString();
      }
  
      /**
       * @since 1.2
       */
      public abstract SQLAction createSQLAction(SQLActionVisitor visitor);
  
      /**
       * Implements default routing mechanism relying on the EntityResolver to find DataMap
       * based on the query root. This mechanism should be sufficient for most queries that
       * "know" their root.
       * 
       * @since 1.2
       */
      public void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery) {
          DataMap map = getMetaData(resolver).getDataMap();
  
          if (map == null) {
              throw new CayenneRuntimeException("No DataMap found, can't route query %s", this);
          }
  
          router.route(router.engineForDataMap(map), this, substitutedQuery);
      }
  }
  