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   *  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.map;
  
  import org.apache.cayenne.query.DefaultEmbeddableResultSegment;
  import org.apache.cayenne.reflect.ClassDescriptor;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A metadata object that defines how a row in a result set can be converted to
   * result objects. SQLResult can be mapped to a single scalar, a single entity
   * or a mix of scalars and entities that is represented as an Object[].
   * 
   * @since 3.0
   */
  public class SQLResult {
  
      protected String name;
      protected List<Object> resultDescriptors;
  
      /**
       * Creates an unnamed SQLResultSet.
       */
      public SQLResult() {
  
      }
  
      public List<Object> getResolvedComponents(EntityResolver resolver) {
  
          if (resultDescriptors == null) {
              return Collections.emptyList();
          }
  
          List<Object> resolvedComponents = new ArrayList<>(resultDescriptors.size());
  
          int offset = 0;
          for (Object component : getComponents()) {
              if (component instanceof String) {
                  resolvedComponents.add(new DefaultScalarResultSegment((String) component, offset));
                  offset = offset + 1;
              } else if (component instanceof EntityResult) {
                  EntityResult entityResult = (EntityResult) component;
                  Map<String, String> fields = entityResult.getDbFields(resolver);
  
                  String entityName = entityResult.getEntityName();
                  if (entityName == null) {
                      entityName = resolver.getObjEntity(entityResult.getEntityClass()).getName();
                  }
  
                  ClassDescriptor classDescriptor = resolver.getClassDescriptor(entityName);
                  resolvedComponents.add(new DefaultEntityResultSegment(classDescriptor, fields, offset));
                  offset = offset + fields.size();
              } else if (component instanceof EmbeddedResult) {
                  EmbeddedResult embeddedResult = (EmbeddedResult)component;
                  Map<String, String> fields = embeddedResult.getFields();
                  resolvedComponents.add(new DefaultEmbeddableResultSegment(embeddedResult.getEmbeddable(), fields, offset));
                  offset = offset + fields.size();
              } else {
                  throw new IllegalArgumentException("Unsupported result descriptor component: " + component);
              }
          }
  
          return resolvedComponents;
      }
  
      /**
       * Creates a named SQLResultSet.
       */
      public SQLResult(String name) {
          this.name = name;
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      /**
       * Returns a list of "uncompiled" result descriptors. Column descriptors are
       * returned as Strings, entity descriptors - as {@link EntityResult}. To get
       * fully resolved descriptors, use
       * {@link #getResolvedComponents(EntityResolver)}.
       */
      public List<Object> getComponents() {
          return resultDescriptors != null ? resultDescriptors : Collections.emptyList();
      }
  
      public void addEntityResult(EntityResult entityResult) {
          checkAndAdd(entityResult);
      }
  
      public void addEmbeddedResult(EmbeddedResult embeddedResult) {
          checkAndAdd(embeddedResult);
      }
  
      /**
       * Adds a result set column name to the mapping.
       */
      public void addColumnResult(String column) {
          checkAndAdd(column);
      }
  
      private void checkAndAdd(Object result) {
          if (resultDescriptors == null) {
              resultDescriptors = new ArrayList<>(3);
          }
  
          resultDescriptors.add(result);
      }
  }
  