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.asterix.optimizer.rules.pushdown.visitor;
  
  import static org.apache.asterix.om.utils.ProjectionFiltrationTypeUtil.EMPTY_TYPE;
  
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Set;
  
  import org.apache.asterix.column.filter.iterable.evaluator.ColumnarRepeatedIterableFilterEvaluator;
  import org.apache.asterix.om.typecomputer.impl.RecordMergeTypeComputer;
  import org.apache.asterix.om.types.ARecordType;
  import org.apache.asterix.om.types.AUnionType;
  import org.apache.asterix.om.types.AbstractCollectionType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.asterix.om.types.IATypeVisitor;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  
  /**
   * TODO this should be removed once we support rewindable readers
   *
   * @see ColumnarRepeatedIterableFilterEvaluator#evaluate()
   */
  public class ArrayPathCheckerVisitor implements IATypeVisitor<Boolean, AbstractCollectionType> {
      private final Set<AbstractCollectionType> seenCollections;
      private boolean firstPath;
  
      public ArrayPathCheckerVisitor() {
          seenCollections = new HashSet<>();
      }
  
      public void beforeVisit() {
          seenCollections.clear();
          firstPath = true;
      }
  
      public boolean containsMultipleArrayPaths(Collection<ARecordType> paths) throws AlgebricksException {
          ARecordType mergedPaths = EMPTY_TYPE;
          for (ARecordType path : paths) {
              mergedPaths = (ARecordType) RecordMergeTypeComputer.merge(mergedPaths, path);
          }
          boolean multiplePaths = !mergedPaths.accept(this, null);
          if (multiplePaths) {
              seenCollections.removeAll(paths);
          }
          return multiplePaths;
      }
  
      @Override
      public Boolean visit(ARecordType recordType, AbstractCollectionType arg) {
          for (IAType child : recordType.getFieldTypes()) {
              if (!child.accept(this, arg)) {
                  return Boolean.FALSE;
              }
          }
          return Boolean.TRUE;
      }
  
      @Override
      public Boolean visit(AbstractCollectionType collectionType, AbstractCollectionType arg) {
          if (firstPath) {
              seenCollections.add(collectionType);
          } else if (!seenCollections.contains(collectionType)) {
              return Boolean.FALSE;
          }
          return collectionType.getItemType().accept(this, collectionType);
      }
  
      @Override
      public Boolean visit(AUnionType unionType, AbstractCollectionType arg) {
          for (IAType child : unionType.getUnionList()) {
              if (!child.accept(this, arg)) {
                  return Boolean.FALSE;
              }
          }
          return Boolean.TRUE;
      }
  
      @Override
      public Boolean visitFlat(IAType flatType, AbstractCollectionType arg) {
          if (arg != null) {
              firstPath = false;
          }
          return Boolean.TRUE;
      }
  }
  